Irradiated Foods

H. Julius / Friends of the Earth 1999

Contents                                1.  Food irradiation and fake research 2.  Food irradiation and the representation of fake research 3.  Food irradiation and safety of irradiated food 4.  Food irradiation who wants it 5.  Fruit irradiation: lack of feasibility 6.  Gamma radiation and lipid peroxidation 7.  Grain irradiation and insects 8.  Grain irradiation and moulds 9.  Irradiated commodities infected with mould spores 10.  Irradiated food and internal bleeding 11.  Irradiated food is peroxidised food 12.  Irradiated fruits: health risks 13.  Irradiated grains health risks 14.  Irradiated vegetables 15.  Irradiation destruction of vitamin C 16.  Irradiation to delay ripening 17.  Irradiation sterilised diets 18.  Radiomimetic effects from irradiated food 19.  Risks of food poisoning from irradiated food

1.  Food irradiation and fake research

Harm from rancid fats

In 1953 some researchers wondered what exactly caused the adverse effects from rancid fats: is it either a toxic agent, or fats becoming less nutritious, or a destruction of nutrients, or a change in function and flora in the gut, or diminished food intake or a combination of them all?

As to nutrient destruction from rancidity, they reviewed research from the 1940s and made the following list: vitamin A and carotene, tocopherol (vitamin E), vitamin D, vitamin K, pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin, ascorbic acid (vitamin C), and the essential fatty acids. These are linolenic, linoleic and arachidonic acid (1).

Furthermore they wondered if their experimental rats were supplied with massive doses of the very nutrients that are destroyed by rancidity plus rancid fat would there be still detrimental effects? So, they tested this (1).

The outcome was inconclusive. A need for more protein was noticed, but whether this was caused by either toxicity or a deficiency remained unclear, while this was the very thing they wanted to know

Their overall conclusion was that a diet containing 10% rancid soybean oil supported almost normal growth in rats when all known essential nutrients were supplied in large amounts and protein constituted 30% of the diet.

The then unknown factors

At that stage it was unknown that massive doses of antioxidant vitamins halted lipid peroxidation (2). Equally unknown was that especially the breakdown products of peroxides were toxic. So, if you halted lipid peroxidation, you blocked the formation of the very substances you wanted to find. Finally it was unknown then that vitamin E deficiency by itself could trigger off lipid peroxidation. Some modern research has created lipid peroxidation in rats solely through a diet deficient in vitamin E or selenium, or both and by diets high in polyunsaturated fats (3).

Fake research

What was a failure in terms of genuine research (inconclusive result), became the success story of the food irradiation lobby.

An example is a ‘research’ on rats fed irradiated pork. The pork was gamma irradiated with spent fuel rods with doses of 28 and 56 kGy. Then the pork was incorporated in the diet for up to 35%. This diet contained a complete vitamin mix plus liver extract. In addition twice a week fat-soluble vitamins (A, D and E) were force fed (4). In other trials the experimental animals got a weekly injection with vitamin E (5). In both researches no differences were found between experimental and control animals during and after the trial.

Crooked fakes

However, not all fake trials went well. A study on dogs for example, fed irradiated meat brought all kinds of thing to light (6). The comments on this result by the researchers is quite revealing:

‘The existence of oxidizing conditions under the influence of irradiation has been demonstrated repeatedly. Polling et al. encountered a partial vitamin E deficiency in rats while feeding irradiated beef. Once these initial marginal deficiencies were corrected, no major differences existed between the control and experimental groups. The peroxide-vitamin E destruction might well have been the case in our beef experiment. Analysis of different meat samples indicated definite elevation in peroxide values of irradiated over control beef. It is also quite probable that peroxide values could have increased during storage periods…It is planned to repeat this experiment with a greater number of dogs and to give closed attention to the intake of the fat soluble vitamins.’(6)

The good thing of this research report was that the reporting was honest. This in contrast to quite a number of feeding trials where the pretense was that everything was fine, while in actual fact the report revealed all kinds of adverse effects. Invariably it was concluded that this particular food was safe for consumption (7, 8, 9, 10).

NATURE

In 1968 Nature dedicated an editorial to the food irradiation issue.(11).

‘The US Army, long the most fervent advocate of irradiation as a means of preserving food, will have to wait until the next Congress for news of a verdict by the Joint Committee on Atomic Energy on the future of the programme for preserving food…

In its letter of April 19, 1968, to the US Army, the Food and Drug Administration argued that the feeding of irradiated bacon and fruit to rats had been followed by marked reductions of the viability of the offspring of the animals. In one series of experiments with bacon and fruit irradiated to the kind of level contemplated in the (planned) Army experiments, the numbers of offspring born to experimental rats turned out to be 23 percent less than the numbers born to control animals. Similar but less striking tendencies were apparent in experiments with dogs, while there were also less significant signs of a reduction of body weight in another series of experiments.

The case against irradiated ham was also supported by evidence of reductions of red cell count and body weight and of an increase of mortality in mice and rats fed irradiated pork and other materials. The letter of April also quoted in a thoroughly tentative way a report of the incidence of pituitary cancer in a group of rats fed irradiated bacon.’ and…’rats fed irradiated peaches were found to have an increased incidence of tumour formation, presumably as a result of the transformation of sugars into other chemicals.’

What remains unclear is why the FDA did not pick up in the first place that the experimental design was invalid.

Politics

Underneath the first page of these reports on feeding experiments one reads: ‘This research was undertaken in cooperation with the Office of the Surgeon General, Department of the Army, under contract’ such and such. The editorial in NATURE identified the AEC or Atomic Energy Commission (US) as the source of the protocol.

Not long after the refusal of the FDA to go along with these poor research results, the Commissioner of the FDA was replaced with a more compliant chap and from then on the FDA became an active promoter of food irradiation.

Research protocol defended

At a symposium on food irradiation in 1966 a justification was given for the ongoing fake research. In a panel discussion the following was said (12):

N. Raica: ‘Since it is known that vitamins, among other nutrients, are destroyed by autooxidized and irradiated oils, it is difficult to separate nutritional effects and toxic product effects when such fats are incorporated in the diet. Supplementary vitamins and antioxidants should be given orally and, if possible , an active component or components isolated from the fats should also be given as separate supplements.’

What remains unexplained is why at all you would want to separate nutritional deficiencies from toxic effects. The task of the promoters of food irradiation is to show that irradiated food is safe. So, all that is needed is checking for adverse effects, no matter their origin. The suggestion of the promoters of food irradiation that lack of toxicity means that the food is safe is nonsensical. Deficiencies can be just as harmful. Vitamin E deficiency leads also to lipid peroxidation.

Genuine research looking for adverse effects without smothering their experimental animals in antioxidant vitamins found plenty of them.

Conclusion

The case supporting the safety of irradiated food hinges on invalid research.

References

1.   S. M. Greenberg et al. 1953. Some factors affecting the growth and development of rats fed rancid fat. J. nutr. 50: 421- 440.

2.   E. A. Dawes et al. 1972. Effects of dietary antioxidants on lipid peroxide formation in animal tissues after whole-body irradiation. Int. J. Radiat. Biol. 22 (1): 23-40.

3.   Hye-Sung Lee et al. 1994. The influence of vitamin E and selenium on lipid peroxidation and aldehydedehydrogenase activity in rat liver and tissue. LIPIDS 29 (5): 345-350.

4.   E. C. Bubl et al. 1960. The growth, breeding and longevity of rats fed irradiated and non-irradiated pork. J. Nutr. 70: 211-218.

5.   van Logten et al. 1978. Investigation of the wholesomeness of autoclaved or irradiated feed in rats. Report 33/78 Alg. Tox. National Institute of Public Health. The Netherlands.

6.   C.M. McCay et al. 1960. Effects of irradiated meat upon growth and reproduction of dogs. Feder. Proc. 19: 1027- 1030.

7.   J.R. Hickman et al.1964. Rat feeding studies on wheat treated with gamma radiation. I. Reproduction. Fd Cosmet. Toxicol. 2: 15-21

8.   J. R. Hickman et al. 1964. Rat feeding studies on wheat treated with gamma radiation. II. Growth and Survival. Fd. Cosmet. Toxicol. 2: 175-180.

9.   I.J. Tinsley et all. 1965. The growth, reproduction, longevity and histopathology of rats fed gamma irradiated flour. Toxicol. Appl. Pharmacol. 7: 71-78

10.   I.J. Tinsley et al. 1970. The growth, reproduction, longevity and histopathology of rats fed gamma irradiated carrots. Toxicol. Appl. Pharmacol. 16: 306-317.

11.   Editorial. NATURE vol 220 November 30, 1968 - page 849.

12.   Food Irradiation - Proceedings of the International Symposium on Food Irradiation, jointly organised by the I.A.E.A. (int. atomic energy agency) and the F.A.O. (food and agricultural organisation) of the UN, held in Karlsruhe 6-10 June 1966. SM-73/38. See discussion after Biological effects of irradiated fats - K. Lang and K.H. Bässler, p 158.

---

2.  Food irradiation and the presentation of fake research

How?

To do fake research is one thing, to get it accepted as genuine is something quite different. How did they do it?

For a start virtually no aspect of food irradiation remained untouched by fake research. Whether this was grain irradiation and insects that survived often with increased mould toxins, or meat and fish irradiation with bacterial problems, or fruit irradiation with increased bruising, or potato and onion irradiation with rotting, no matter what, fake research attempted to dispel all the adverse findings from genuine research.

This was often done by introducing more than one variable to manipulate a predetermined outcome. In addition the ploy of unrepresentative generalisation was used. So, a specific result was presented as having a general meaning.

One example concerns research on Salmonella. Under very special circumstances 2.5 kGy could control Salmonella. The report stated that ‘under the given circumstances’ etc., etc. This clause was left out in subsequent references and the results were generalised. So, from then on you read in pro-food-irradiation literature that only 2.5 kGy is needed to control Salmonella, while the reality is that you need around 8 kGy. There are more than 2000 different Salmonella strains all with different radiation sensitivities depending on what nutrient they are on. Only around 20 strains were tested so far. So much for the reality.

Results only reported

Fake research produced a flood of research reports often hidden in Technology Journals where there is no peer review. At regular intervals all results from fake and genuine research were put together into a summary report. For obvious reasons it would be impossible to report all the varying research protocols that had been used. So, the only thing that was reported were the results.

These summaries were sent to experts in their field who were invited to attend a symposium for discussions (a symposium is a gathering of scientists for exchanging views). As far as the experts were genuine they would have been hard pressed for time. So, a summary report would have been welcomed. They would have assumed that the compilers of these reports were genuine scientists and they relied on this. So, generally the original research papers were not checked by the experts.

These symposia were also attended by experts ‘summoned’ to these meetings, because they were receiving Grants from the nuclear industry. Even if they would have suspected that some research might not stand up to closer scrutiny, they would have kept silent as speaking up could endanger their precious Grant.

And then there were the genuine fakers, scientists who wholeheartedly had sold out to the nuclear lobby because of the money involved. They often became active promoters. The nuclear industry pays very well you know. So, these symposia were attended by a very mixed group of people.

Misrepresentation

Reporting research results only made it easier to misrepresent genuine research. This was the case with research that showed that increasing irradiation doses resulted in more fatty acids in grains which stimulated production of mould toxins. In the summary report for discussion at the symposium however, this research was mentioned with the remark that no clear relationship was found between the upsurge in toxin production and radiation dose (1,2). So, this remark stated the very opposite of the research findings.

If you come across one blatant misrepresentation, then you start to wonder how many more there are in these summaries. The more so as genuine scientists exposing the hazards of irradiated food have been harassed and vilified by the rented crowd of fake scientists. Especially the research done on irradiated wheat by the National Institute of Nutrition of India in the 1970s, was most unwelcome and anything was done to discredit it.

Genuine research ending

The bulk of genuine food irradiation research was done in the 1950s and 1960s. In November 1968 NATURE ran an Editorial summing up the adverse effects from feeding animals irradiated food and the dissatisfaction of the FDA with these results (3). In 1969 a review outlined the problems and dangers of irradiated food and this was followed by another review in 1971 of similar content (4, 5). So, genuine research on food irradiation ended around this time, except in India.

Fake research moved on

There was no letting up by the nuclear industry. The FDA was ‘massaged’ just as the WHO (the funds for the World Health Organisation come largely from US interests) and the Symposia continued unabated. In the end genuine research was completely crowded out by fake research. And finally at the 1980 Symposium it was solemnly declared that food irradiated for up to 10 kGy was safe. By then the whole food irradiation issue had entered Fantasy-Land.

The poor ignorant scientist

The reports of these Symposia were published (‘Recent Advances in Food Irradiation’ for example) So, any scientist ignorant about food irradiation would go to his/her scientific library and find those symposia books on the shelves. And there was written that irradiated food was safe. So, inquiries set up by governments under public pressure would hear from independent scientists what they had read in those symposium summaries. Thus, misinformation has been well built into the system. In addition any government inquiry is hampered by statements from biased researchers because of the Grants they receive.

Statements supporting faked safety

During campaigns to introduce food irradiation scientists with Grants from the nuclear industry were often forced to make positive statements on the issue. Sometimes they had to admit that they did not know anything about irradiated food.

Here are a few examples: ‘Over the last 30 years research has been unable to show there are any adverse side-effects from irradiated food. So much consumer resistance has been the result of misinformation.’ A statement from an Australian nutritionist in May 1988 who was receiving a Grant from the nuclear industry and who had admitted to know nothing about irradiated food.

Here is another one: ‘The safety of food irradiation has been extensively studied since the 1960s and the technology was endorsed by the WHO. While safety has been well established, there is still a need to overcome scepticism and prejudice within the community’. A not too well informed officer from the Queensland Health Department in August 1999. Such statements complement all the fake research on food irradiation of the last 50 years.

Perhaps we should change such nonsense statements into: ‘While the lack of safety has been well established, there is still a need to overcome ignorance within the scientific community.’

References

1. Priyadarshini, E. et al. 1979. Effect of graded doses of gamma irradiation on aflatoxin production by Aspergillus parasiticus in wheat. Food Cosmet. Toxicol. 17: 505-507.

2. Teufel, P. 1983. Microbiological aspects of food irradiation. In: Recent Advances in Food Irradiation (eds. P.S. Elias and A.J. Cohen) by Elsevier Biomedical p.223.

3. Editorial. NATURE vol 220 November 30, 1968 - page 849.

4. Schubert, J. 1969. Mutagenicity and cytotoxicity of irradiated foods and food components. Bulletin WHO 41: 873- 904.

5. Kesavan, P.C. et al. 1971. Cytotoxic and mutagenic effects of irradiated substrates and food material. Radiation Botany 11: 253-281

---

3.   Food irradiation and safety of irradiated food

The claim

It is repeatedly claimed by the proponents of food irradiation that irradiated food is safe.

The reality

The irradiation process bombards food with high energy photons (ionising radiation). As a result the food becomes loaded with free radicals, which are very harmful chemicals. These chemicals have been associated with the onset of cancer and early aging.

Free radicals are formed in many normal life processes and our natural defenses are the anti-oxidants in our food. Anti-oxidants neutralise free radicals and are also called free radical absorbers. Some well known anti-oxidants are beta carotene and the vitamins A, C and E.

It is obvious that when you start to eat food high in free radicals that you deplete your natural levels of anti-oxidants. So, you become more prone to free radical damage, whatever form it takes. To keep in balance you would have to ingest much higher levels of anti-oxidants.

Supplement or die

Supplementation with extra ant-oxidants is precisely what the proponents of food irradiation have been doing in their animal trials. At first they used anti-oxidant vitamins in excessive quantities. Later they used less well known food components and chemicals with strong ant-oxidant working.

Wrong claim

Invariably they claim that their research shows that irradiated foods are safe. But this is misunderstanding the results of their own research. So, what does their research show?

Correct claim

Their research shows that a wide variety of anti-oxidants fed in large quantities is highly effective in protecting experimental animals from the ravages of free radicals.

Scientific research

Genuine research aimed at finding out what really happens, used standard animal house diets. They were mixed with irradiated foods. Normally, standard animal house diets contain also anti-oxidants, but in modest quantities. Just as in any other healthy diet.

In this kind of research the free radical overload in irradiated foods became very visible through the many adverse effects that showed up.

Adverse effects

• lowered immune resistence (1,2,3)
• upsurge in abnormal lymph cells (4,5,6,7 and 8)
• decreased fertility (7, 9, 10, 11, 12, 13, 14, 15, 16)
• damage to kidneys ( 17)
• depressed growth rates (12, 18, 19)
• vitamin A and B deficiencies (9)
• vitamin C deficiency (20)
• vitamin E deficiency (10)
• vitamin K deficiency (21)

Scientific comment

One research examining the testes of rats fed for 20 months a standard animal house diet containing irradiated products noted:

"It is noteworthy that the structural changes observed were similar in many respects to those arising in the testes during prolonged exposure to radiation…It can therefore be suggested that prolonged entry of such substances into the body in the composition of irradiated food may give rise to changes in the testes, as also in other organs, similar to the after effects of chronic irradiation. This hypothesis is confirmed by the direct dose dependence established between the severity of the structural changes in the testes and the dose of radiation of the foods consumed."(14)

References

1. Hickman, J.R., T. Greenwood, J.O.Bull and F.J. Ley. 1964. Rat feeding studies on wheat treated with gamma radiation II. Growth and survival. Fd Cosmet. Toxicol. 2:175-180.

2. Ehrenberg, L. & G. von Ehrenstein. 1960. Riso Report No.16, p.41. as referenced in WHO Technical Report Series No. 316 Appendix 6, Geneva 1965.

3. Vijayalaxmi. 1978. Immune response in rats given irradiated wheat. Br.J. Nutr. 40:535-541

4. Bhaskaram, C. and G. Sadasivan. 1975. Effects of feeding irradiated wheat to malnourished children. Am.J.Clin.Nutr. 28:130.

5. Vijayalaxmi. 1978. Cytogenetic studies in monkeys fed irradiated wheat. Toxicology 9:181-184.

6. Vijayalaxmi and G. Sadasivan. 1975. Chromosome aberrations in rats fed irradiated wheat. Int.J.Radiat.Biol. 27 No.2:135-142.

7. Vijayalaxmi. 1976. Genetic effects of feeding irradiated wheat to mice. Can.J.Genet.Cytol. 18:231-238.

8. Renner, H.W. 1977. Chromosome studies on bone marrow cells of Chinese hamsters fed a radio-sterilized diet. Toxicology 8:213.

9. McCay, C.M. and G.L.Rumsey. 1960. Effects of irradiated meat upon growth and reproduction of dogs. Fed. Proc. 19:1027-1030.

10. Hickman, J. R. , D.L.A. McLean and F.J. Ley. 1964. Rat feeding studies on wheat treated with gamma irradiation I. Reproduction.. Fd Cosmet.Toxicol. 2:15-21.

11. Tinsley, I.J., J.F. Bone and E.C. Bubl. 1965. The growth, reproduction, longevity and histopathology of rats fed gamma irradiated flour. Toxicol. Appl.Pharmacol. 7:71-78.

12. Tinsley, I.J., J.F. Bone and E.C. Bubl. 1970. The growth, reproduction, longevity and histopathology of rats fed gamma irradiated carrots. Toxicol. Appl. Pharmacol. 16:306-317.

13. Vijayalaxmi and K.V. Rao. 1976. Dominant lethal mutations in rats fed on irradiated wheat.. Int.J.Radiat.Biol. 29-No.1:93-98.

14. Ivanov, A.E. and A.I. Levina. 1981. Pathomorphological changes in the testes of rats fed on products irradiated with gamma rays. 0007-4888/81/9102-0232 $7.50 1981. Plenum Publishing Corporation. Translated from: Byulletin Eksperimental ‘noi Biologii i Meditsiny, vol.91, No.2 pp.233-236.

15. Bugyaki. L., A.R. Deschreiber, J. Moutschen, M. Moutschen-Dahmen, A. Thijs and A. Lafontaine. 1968. Les aliments irradies exercent-ils un effet radiomimetique? (Do irradiated foods have a radiomimetic effect?). Atompraxis 14-No.3:112-118.

16. Bugyaki et al. WHO Technical Report Series No. 451. p. 28, Geneva 1970.

17. Levina, A.I. and A.E. Ivanov. 1978. Pathomorphology of the kidneys in rats after prolonged ingestion of irradiated foods. 0007-4888/78/8502-0236 $7.50 1978. Plenum Publishing Corporation. Translated from: Byulletin ‘Eksperimental’ noi Biologii i Meditsiny, vol.85-No.2, pp.230-232.

18. van Logten, M.J., J.M. Berkvens and R. Kroes. 1978. Investigation of the wholesomeness of autoclaved or irradiated feed in rats. Report 33/78 Alg Tox - National Institute of public Health - Utrecht/Bilthoven. The Netherlands.

19.Renner., H.W. and D. Reichelt. 1973. Zur frage der gesundheitlichen Unbedenklichkeit hoher Konzentrationen von freien Radikalen in bestrahlten Lebensmitteln. Zbl.Vet.Med.B20:648-66.

20. Blood, F.R. , W.J. Darby, M.S. Wright and G.A. Elliott. 1966. Feeding of irradiated peaches and whole and peeled oranges to monkeys. Toxivcol..Appl. Pharmacol. 8:247-249.

21. Metta, V.Ch., M.S. Mameesh and B.C. Johnson. 1959. Vitamin K deficiency in rats induced by the feeding of irradiated beef. J. Nutr. 69:18-22

---

5.  Food irradiation: who wants it?

In the Review of Applied Entomology vol.54, 1966 at p. 249 we find a review of a book. It concerns P.B. Cornwell as editor of a bundle of research papers on insect irradiation. The title of the book: The entomology of radiation disinfestation of grain. A collection of original research papers.

The book review in this issue of the Review of Applied Entomology starts as follows:

‘The work reported in this volume was carried out by the Entomology Group of the Wantage Research Laboratory in 1955-61. This group was established as part of the contribution of the United Kingdom Atomic Energy Authority to the finding of possible industrial applications of the new sources of radiation now available.’

A nuclear waste problem

The Wantage Research Laboratory is a major nuclear facility in the UK. The push for food irradiation has always come from the nuclear establishment. The idea was and is to use nuclear waste as radiation source in food irradiators. In other words it is an attempt to spread nuclear waste widely: many glorified nuclear dumps as food irradiators instead of the present large, few nuclear dumps that are running out of space.

The starting up is always done with radioactive cobalt. This is not a waste product of the nuclear industry. It is specially made for the purpose. It is to get a foot in the door. The real intention is to switch over to radio-active cesium. This is the nuclear waste and its danger is that it is water soluble. Any spill can have very bad consequences for the community where this happens.

Research with radioactive caesium

A number of research groups have used radio-active cesium in their insect irradiation experiments. It shows the real intentions. One group is Japanese their research is mentioned in the Review of Applied Entomology -Series A 1976 vol.64 No.12 at p.1969 no.7099 Kiyoku, M. et al.

Another research with radioactive caesium was done in Hungary: Review of Applied Entomology - Series A 1976 vol.64 No.9 at p. 1476 no.5315. Szentesi, A.

And a third research with radioactive caesium was done in Canada. Review of Applied Entomology - Series A 1975 vol.63 No.7 at p.637 no.4637. Chawla, S.S. et al.

These are the researches I came across. There are probably a lot more.

Irradiation unsuitable

In the 1950s and 1960s much genuine research was done on food irradiation by universities, research centra and so on. And what was the outcome? That the technology was found to be unsuitable as a food technology. So, genuine research ceased.

However, the nuclear lobby has never accepted this and with fake research, false reviews and bribing ("grants" we call them) they try to get their way. It shows that they do not really understand anything of food technology, nor of science.

It seems their only concern is to get rid of their nuclear waste.

---

6.   Irradiated fruit: lack of feasibility

Why irradiate fresh fruit?

Irradiation would suppress decay moulds and kill insects as a quarantine measure. However, it turns out that fruits are more radiation sensitive than moulds and insects are.

Damage to fruit

Ionising radiation causes chemical changes in the structure of cell wall components, whereby cellulose, hemicellulose and pectin are irreversibly cleaved (1, 2). As a result the cell walls become leaky and calcium is released in proportion to the irradiation dose. This occurs up to 6 kGy. At higher doses up to 80% of calcium is lost (3). This calcium loss plays an important role in the softening of fruit and other plant tissues (vegetables).

There is also an increased tendency to lose water and a major reason for refrigeration of irradiated produce in transit is to prevent this water loss (1, 2). An accompanying problem is that fruits sensitive to low temperatures become even more chilling sensitive after irradiation. This was found with bananas, lemons, oranges and tomatoes at irradiation doses well below the required ones (1, 2).

Damage in transit

Because of this overall tissue softening irradiated produce is much easier damaged in transit than their unirradiated counterparts. Irradiated consignments transported over some distance like other normal fruit, arrived crushed and bruised and was unacceptable.

What are critical doses?

This very much depends on the fruit in question.

Citrus

• the irradiation dose for Australian Washington Navel and Valencia oranges should not exceed 0.30 kGy because of the risk of rind injury (4).
• Californian navel oranges irradiated with around 0.35 and 0.50 kGy showed brown pitting and rind injury plus flavour changes (5).
• Another research paper mentions three other reports where oranges irradiated at 0.50 developed brown skin blemishes and changes in flavour and odour. after 2-4 weeks storage (6).
• Hawaii Californian Valencias could tolerate up to 0.50 kGy.
• Juice and fresh sections of Marsh seedless grapefruits from Florida developed significant changes in flavour after irradiation with 0.25-0.50 kGy (7).

This little survey shows that many kinds of citrus fruit are damaged at a dose of 0.50 kGy and higher. Major citrus decay moulds like blue and green Penicillium require more than 0.50 kGy to keep them under control (0.80 and 1.20 kGy respectively). And black rot or Alternaria needs more than 3 kGy (8). This means that irradiation cannot be used to suppress decay moulds in citrus fruit.

Stone Fruits

• peaches irradiated at 0.50 kGy showed significant changes in colour; nectarines showed changes in aroma and plums showed changes in colour and texture (9).
• Californian Regina Freestone peaches irradiated with 0.65 to 0.75 kGy developed loss of flavour or an ‘off-flavour’ plus changes in sourness.
• Bing cherries irradiated at 0.60-0.80 kGy showed a high degree of shriveling and changes in taste (10).
• apricots could tolerate not more than 0.50 kGy else tissue softening became unacceptable (11).

The picture for stone fruit is similar to that of citrus fruit. Although stone fruit can tolerate higher radiation doses, the stone fruit decay moulds are also more tough. The greatest threat comes from brown rot caused by the mould Monilinia fructicola and requires more than 2 kGy to keep things under control.

Berries

• Boysenberries and raspberries can tolerate up to around 1 kGy.
• Strawberries on the other hand can tolerate 2 kGy and higher up to 4 kGy depending on variety (1).
• However, some Shasta strawberries got a ‘cooked’ odour and an off-flavour plus a water soaked interior at 4 kGy. No changes in appearance occurred for 4 days but then there was a gradual loss of pigment and after 10 days there was extensive bleaching (12). What makes strawberries so different from other fruits irradiation-wise is not well understood.
• Grapes can stand irradiation depending on the variety. Thomson seedless grapes and mature Tokay grapes showed no symptoms of injury after a dose of 2 kGy. Emperor grapes could even tolerate up to 5 kGy (12). But other table grapes could only tolerate up to 0.50 kGy and displayed softening plus severe off-flavours (11).

The picture in berries differs from that of citrus and stone fruit, because strawberries form a irradiation success story: some varieties can tolerate up to 4 kGy. The major decay mould in strawberries, gray mould or Botritus cinerarea, requires around 2.5 kGy to keep under control (13). The other major strawberry disease is leak or Rhizopus stolonifer which cannot grow below 10 EC. So, proper refrigeration will do the job.

And grapes? Because grapes are destined for long-term storage they would require almost complete inactivation of gray mould and this would need at least 10 kGy (11).

The overall conclusion must be that fruit is too radiation sensitive to use irradiation for controlling decay moulds.

Quarantine and irradiation

The major fruit flies of interest are:

• Mediterranean fruit fly (Ceratitis capitata W.)
• Melon fly (Dacus cucurbitae Coq.)
• Oriental fruit fly (Dacus dorsalis Hendel)
• Queensland fruit fly (Dacus tryoni Frog.) (14)

Fruit fly life cycle

The fruit fly cycle is as follows: eggs are laid

inside the fruit right under the skin or a few mm deep into the pulp. After hatching the larvae begin to feed and burrow into the pulp. They shed their skin twice as they feed and grow. The mature larvae leave the fruit to find a suitable place for pupation often in the soil. After the adult fruit fly emerges and attains sexual maturity a new cycle is started.

Radiation sensitivity

Young eggs, larvae, pupae and adults are more radiation sensitive than older eggs, larvae, pupae and adults.

The major problem with irradiation for quarantine purpose is that a quick kill of eggs, larvae, and an occasional pupa would require doses in excess of 1 to 2 kGy for melon, oriental and Mediterranean fruit flies (15). For the Queensland fruit fly a dose of 0.80 kGy would be needed. These doses are too high for most fruits. Therefore only low doses can be used for a slow kill resulting in alive irradiated immature insects. But there is no way to distinguish between immature irradiated insects and insects not exposed to irradiation.

Similar findings were made concerning the mango weevil and radiation sensitivity of mangoes. Only the South African Kent mango is just as strawberries an irradiation success story.

The overall conclusion must be that irradiation as quarantine measure is unsuitable.

References

1. Maxie, E.C. et al. 1966. Food irradiation physiology of fruits etc. Advances in Food Research 15: 105-145.

2. Maxie, E.C. et al. 1971. Physiological limitations to irradiation of fruit. Pp. 93-100. In: Proceedings of a Panel on use of irradiation to solve quarantine problems in international food trade. Joint FAO/IAEA Division of Atomic Energy in food and agriculture, held at Honolulu, Hawaii, 7-11 Dec. 1970.

3. Vienna IAEA. Shah, J. 1966. Radiation induced calcium release etc. Nature 211: 776-777.

4. Macfarlene, J.J. et al. 1968. Effects of gamma irradiation on oranges etc. Austral. J. Exp. Agric. and Animal Husbandry 8: 625-629.

5. O’Mahony, M. et al. 1987. Sensory technique for measuring etc. J. Food Sci. 52: 348-353.

6. O’Mahony, M. et al. 1985. Sensory evaluation of oranges etc. J. Food Sci. 50: 639-646.

7. Moshonas, M.G. et al. 1982. Irradiation and fumigation effects etc. J. Food Sci. 47: 958-960.

8. Sommer, N.F. et al. 1964. Sensitivity of citrus fruit decay fungi etc. Radiation Botany 4: 317-322.

9. Moy, J.H. et al. 1983. Radiation disinfestation etc. J. Food Sci. 48: 928-931.

10. O’Mahony, M. 1985. Sensory evaluation Bing cherries etc. J. Food Sci. 50: 1048-1050.

11. Maxie. E.C. et al. 1971. Infeasibility of irradiated fruits and vegetables. HortScience 6(3): 202-204.

12. Nelson, K.E. et al. 1959. Ionizing radiation to control Botrytis rot etc. Phytopathology 49: 475-480.

13. Sommer, N.F. et al. 1966. Ionizing radiation to control etc. Advances in Food Research 15: 147-193.

14. Christenson, L.D. et al. 1960. Biology of fruit flies. Annual Review of Entomology 5: 171-192,

15. Balock, J.W. et al. 1963. Effects of gamma irradiation on etc. J. Econ. Entomol. 56(1): 42-46.

---

6.   Gamma radiation and lipid peroxidation

Radiation energy

Irradiation must be seen as a bombardment with high energy particles, called photons. To get a better idea of the energies involved, compare the following facts. For normal chemical processes such as the breaking and forming of bonds between molecules, an energy of 5 to 7 electron volt is needed.

X-rays for medical purposes on the other hand, carry photons of 100 000 electron volt. And the X-rays for food irradiation carry photons of 1 to 5 million electron volt (1, 2). Similar high energy photons are produced by radioactive materials like cobalt-60 or cesium-137. Then the radiation is called (-radiation (gamma radiation).

So, compared with normal chemical processes, the energies of gamma radiation are immense.

Misrepresentation

Some promoters of food irradiation have suggested that because very little heat is developed, the energy for irradiation is too little to do much harm. However, this energy is not spread out evenly like heat and can therefore be very harmful. For example, a dose of X-rays that would kill a man if given to the whole body, would in terms of heat be less than that from drinking a cup of coffee (3).

So, to compare the intense energy of gamma radiation with the evenly spread out energy of heat is meaningless.

Violent snooker

To get a better picture of what is really going on during irradiation, you could compare the effects of high energy photons with a game of violent snooker.

Many high energy photons do not hit anything and pass right through. They are so tiny and there is so much open space on a molecular scale in and between molecules that they can do this and no harm is done. But the photons that do hit molecules wreck havoc.

Ionising radiation

Molecules that are hit by a (-photon have an outer electron ripped off them through the high impact. Such molecules become electrically charged by losing this electron and are called ions. Hence the name ionising radiation. A more clumsy name would be ‘damaged molecules radiation’ and would spell out what is going on.

The electrons that are ripped off shoot away with the energy of the (-photon and continue the snooker game. Thereby they rip electrons away from other molecules. So, there is a cascading effect and an increase in high energy electrons. This snooker game continues till all excessive energy has been dissipated. Excessive energy means here the difference between a million electron volt and 5 to 7 electron volt.

Free radical formation

The damaged molecules are extremely reactive because they try to get that electron back that was taken away from them. They are called free radicals.

As biological systems consist for 55-80% of water, the main interaction of radiation is with water molecules (4).This results in the formation of the hydroxyl and the superoxide radicals and hydrogen peroxide (2, 5, 6). All these substances are extremely reactive, call them corrosive if you wish, and react readily with the molecules of biological cells.

Cell membranes

The walls of biological cells are composed of so called membranes. These structures are selectively permeable, which means that they let certain substances through and block other ones. They maintain a suitable environment inside the cell by letting nutritional substances in and waste products out and perform many other functions. Cell membranes are therefore dynamic structures. They are composed of a double layer of lipids (fats and fatty compounds) with proteins dispersed throughout. Different cell membranes have different proportions of lipids. Membranes are generally high in polyunsaturated fatty acids and this makes them prone to free radical attack.

Lipid peroxidation

A chain reaction is started when lipid molecules are attacked by free radicals. This chain reaction goes as follows: a free radical reacts with a lipid molecule and destroys it. But a new free radical is formed in the process. This reacts with the next lipid molecule and destroys it, again with formation of a new free radical. And so on.

Only a free radical scavenger can stop this process. Then the scavenger reacts with the free radical and destroys it. Another way to stop this cascading process is when two radicals bump into each other. They destroy each other and form a stable product (7).

The effects of lipid peroxidation

As a result of this chain reaction cell membranes are severely compromised or even partly destroyed. They become leaky, mineral exchanges are hampered and essential life processes are slowed down or even halted.

A particularly important membrane is of course the one surrounding the cell nucleus. When leaky, reactive substances can enter the nucleus, they can react with the DNA that is located there and cause permanent damage. This can result in mutations. Is it any wonder then that lipid peroxidation has been linked to the onset of tumors and cancer?

Natural protection

Fortunately there are millions and millions of cells

and nature has put a few breaks in place against lipid peroxidation. A number of enzyme systems counter superoxide damage and other biological molecules act as free radical scavengers, such as vitamin E, A and glutathion. This natural protection is needed because the superoxide radical is also produced by normally functioning enzyme systems such as the zanthine oxidase system (7).

Tissue levels of vitamin A, E and antioxidant enzymes protect against radiation damage. For example, experimental animals exposed to whole body radiation and placed on vitamin E deficient diets were more sensitive to radiation than control animals on normal diets. Also, mice receiving vitamin E supplements were less sensitive to radiation injury than mice on normal diets (7). In combination with selenium the antioxidant effect of vitamin E becomes even more pronounced (8).

And so what?

What has this all to do with food irradiation? So far we have discussed lipd peroxidation from whole body radiation.

It appears that animals fed irradiated food display the same symptoms as animals undergoing whole body radiation. This indicates that similar biochemical processes occur in animals fed irradiated food and animals undergoing whole body irradiation. The effect from food has been called radiomimetic.

References

1. Gofman, J.W. 1981. Radiation and human health, by Sierra Club Books - San Francisco, p.21-22

2. Lawrence, Ch.W. 1971. Cellular Radiobiology, by Edward Arnold Co. london, p.35-37.

3. Hall, E.J. 1978. Radiation and life, by Pergamon Press, Oxford. Pp.16-17

4. Walden, T.L. et al. 1990. Biochemistry of ionizing radiation, by Raven Press, New York. P.20.

5. Pizzarello, D.J. et al. 1975. Basic Radiation Biology, by Lea & Febiger, Philadelphia. Pp.22-23

6. Fridovich, I. 1978. The biology of oxygen radicals. Science 201: 875-880.

7. Op. Cit. 4 at pp. 36-39.

8. Tappel, A.L. 1965. Free radical lipid peroxidation damage and its inhibition by vitamin E and selenium. Federation Proceedings 24: 73-78.

---

7.   Grain irradiation and insect pests

Which insects?

A booklet from the Queensland Department of Primary Industries spells them out for Queensland:

Common name                Scientific name
Rice weevil                Sitophilus oryzae
Lesser garin borer         Rhyzoperta dominica
Rust-red flour beetle      Trilobium castaneum
Dried fruit beetle         Carpophilus dimidiatus
Cadelle                    Tenebroides mauritanicus
Bean weevil                Acanthoscellides obtectus
Saw-toothed grain beetle   Oryzaephilus surinamensis
Flat grain beetle          Cryptolestes pulillus
Tobacco beetle             Lasioderma serricorne
Tropical warehouse moth    Ephestia cautella
Indian meal moth           Plodia interpunctella
Angoumois grain moth       Sitotroga cerealella

Radiation sensitivity

The problem with insects is that you are dealing with more than one individual per insect. You have eggs, larvae, pupae and adults. In general the adults are the most radiation resistant.

It turns out that Sitophilus oryzae would need a dose of 20 krad (0.20 kGy) to kill about 99.9% of adults within 21 days. For Oryzaephilus surinamensis the same dose resulted in complete mortality of adults within 15 days (1). The same dose gave ‘very high mortality’ of adults from Rhyzoperta dominica (2).

Tribolium castaneum was toucher: adults died in 16 days after 50 krad (0.50 kGy) or in 12 days after 100 krad (1 kGy) (3)

Lasioderma serricorne needed 2500 Gy (2.5kGy) for 100% mortality of adults and 750 Gy or 0.75 kGy for 100% mortality of all immature stages (4).

Plodia interpunctella and Sitotroga cerealella are the hardest nuts to crack. All stages of these insects were given doses of about 13, 17, 25, 45 and 100 krad (0.13, 0.17, 0.25, 0.45 and 1 kGy).

It turned out that ‘the life of insects treated as adults or pupae was not greatly shortened by any of the treatments.’(5).

These are only a number of the in Queensland listed insects as major storage pests. The required dose to kill adults within 1 month varies in the mentioned insects from a low 0.20 kGy to a comparatively high 2.5 kGy.

Critical points in dose range

There are two critical points in this dose range. The most obvious one is that you are not supposed to kill the grain and this can happen from 1 kGy onwards (6, 7). Nobody is interested in silos with dead, stinking grain. And the second critical point is from about 0.50 kGy onwards. Between 0.50 and 1 kGy it has been found that irradiated moulds producing aflatoxins are stimulated in producing more toxin when they get a chance to grow.

Insects love irradiated grains

It is an illusion to think that once grain has been disinfested it will stay this way. When the little critters get a chance you have them back. Well, how do they thrive on irradiated grain? It turns out they love it. So, think twice before you start irradiating.

Rhyzoperta dominica was reared on irradiated rice with doses varying from 20 to 5000 krad (0.20 to 50 kGy). This resulted in an increase in adult life-span and fecundity of the next generation (8).

Tribolium castaneum had similar preferences. Reared on irradiated diets the numbers in offspring of the second, third and fourth generation were significantly higher than the offspring on unirradiated diet (9).

References

1. Hoedaya, M.S. et al. 1973. Radiation effects on four species of insects etc. 281-294. Pasar Jum’at Research Centre, National Atomic Energy Agency, Jakarta, Indonesia.

2. Abdul Matin, A.S. et al. 1974. Susceptibility of Rhyzoperta dominica to ionizing radiation. Journal of Stored Products research 10(3/4) 199-207. - Review of Applied Entomology -Series A 1975 vol.63 No.10 p.1052 no.3864.

3. Adem, E. et al. 1979. Responses of Prostephanus etc. and Tribolium castaneum to gamma irradiation. Canadian Entomologist 111 (10) 1111-1114. - Review of Applied Entomology - Series A 1980 vol. 68 N0.6- p.392 no.3124

4. Els, J. M. et al. 1978, recd. 1980. The lethal effect of gamma irradiation on Lasioderma srricorne. Phytophylactica 10 (4) 127-128. Tobacco Research Institute , Private Bag, Rustenburg, 0300 South Africa. - Review of Applied Entomology - Series A 1980 vol.68 No.12 - p.826 no 6652.

5. Cogburn, R.R. et al. 1966. Gross effects of gamma radiation on the Indian-meal moth and the Angoumois grain moth. J. econ. Ent. 59 no.3 pp. 682-685. - Review of Applied Entomology vol.54. - p.495

6. Pesson, P. 1963. Utilisation des radiations ionisantes pour la protection des denrees contre les insects nuisibles. Industr. agric. 80 no.3 pp. 211-225.- Review of Applied Entomology vol.54, 1966. P 58.

7. Wills, P.A. 1988. Critical review of a submission by H. Julius , Food Irradiation and Moulds: a time bomb. An ANSTO report p.34.

8. Wiendl, F. et al. 1974, recd. 1976. Mortalidade e reproducao de Rhyzopertha dominica. Anais da Sociedade Entomologica do Brasil. 3 (1) p. 34-43. - Review of Applied Entomology - Series A 1977. Vol. 65 No.2, no.875

9. Tilton, E.W. et al. 1973. Progeny production by S. oryzae and Tribolium castaneum reared for several generations on irradiated diets. Journal of the Georgia Entomological Society 8 (3) pp. 168-173. - Review of Applied Entomology - Series A 1974 vol. 62 No.11. p.1222 no. 4603.

---

8.   Grain irradiation and mould toxins

Mould problems

We all know that moist goods get mouldy after some time. Moulds grow from tiny spores floating in the air, which are so tiny that they are invisible to the naked eye. When they land onto a surface they germinate if the circumstances of moisture, nutrients and temperature are right.

All agricultural commodities are full of mould spores and the best way of dealing with them is by keeping things dry. Unfortunately this is not always possible due to rain during harvest, poor storage facilities or problems during transport. As a result it occurs frequently that people and cattle eat mouldy food. This can be dangerous as many moulds produce powerful toxins.

The aflatoxins are well known from mouldy peanuts, but you can find them on any mouldy surface. Most toxins are produced by the Aspergillus, Penicillium and Fusarium moulds.

Grain irradiation

One of the applications of food irradiation would be irradiation of grain as a means of insect disinfestation. The dose recommended by the Joint Expert Committee for this purpose was 0.75 kGy (1). This means in practice a dose range of 60 to 90 kGy.

When microbiologists started to understand what food irradiation was, they also started to understand some of its implications. If grain were to be irradiated, then mould spores were irradiated with it. And what effect would this have on the moulds grown from these irradiated spores? So, they set out to investigate this.

Mould spore irradiation

They focused on the spores of toxin producing Aspergillus moulds: the aflatoxin producers. These were irradiated at different irradiation doses and then grown on a number of suitable substances like wheat germ, cracked wheat, rice, bread and so on. Then the amount of produced toxin was measured and compare with the toxin produced from unirradiated spores of that same mould grown under the same circumstances.

Upsurge in toxin formation

It was found that moulds grown from irradiated spores produced much more toxin than moulds from unirradiated spores. The most alarming finding was that this occurred precisely in the narrow irradiation range available for insect disinfestation. This is the range of 0.50 kGy to 1 kGy as beyond 1 kGy the viability of the irradiated grain is at stake.

Not only more toxin was formed, but from 0.50 kGy onwards a steep upsurge of toxin production occurred (2, 3).

When this research was repeated with other toxin producing moulds the same picture emerged: gamma irradiation stimulated toxin production (4, 5, 6, 7, 8).

Fake research

The standard answer from the promoters of food irradiation was fake research. And lo and behold they did not find an upsurge in toxin production. What did they do? They used oxygen deprivation to reduce toxin production, they used irradiation doses below 0.50 kGy (but this dose is not sufficient for insect disinfestation) and one "research" used even a mould inhibitor. In addition they misrepresented the genuine research. For example there is this research from Schindler et al.(3) that found that the peak production of aflatoxin of a particular toxin producing mould was at a dose of 0.90 kGy. Then the graphic went fairly steep down till around 2.25 kGy followed by a very steep decline till 4.3 kGy when toxin production ceased.

Misrepresentation

The promoters reviewed this research and wrote that the highest toxin production was at an irradiation dose of 4.3 kGy (9). This is well outside the insect disinfestation range and would be of no concern to anyone.

The problem of these reviews is that they are relied on by experts not doing their homework by looking up the original research papers. And here comes fake research in. The large number of reports from fake research causes a flood of research papers and most scientists have not the time to go through them. So they rely on reviews assuming that they are reliable.

In other words decisions made by so called experts are often based on misinformation that is cleverly and deliberately put in place.

Conclusion

Irradiation of grain and other commodities against insect infestation would create more problems, than it would solve.

References

1. WHO Technical Reports Series No.451, p.15 (1970).

2. Jemmali, M. et al. 1969. Influence of gamma irradiation of A. flavus spores on the production of Aflatoxin B1. C.R. Acad. Sc. Paris, 269 (D): 2271-2273.

3. Schindler, A.F. Et al. 1980. Enhanced aflatoxin production by A. flavus and A. parasiticus after gamma irradiation etc. J. Food Protect. 43: 7-9.

4. Applegate, K. L et al. 1973. Increased aflatoxin production by A. flavus via cobalt irradiation. Poultry Science 52: 1492 - 1496.

5. Applegate, K .L et al. 1973. Increased aflatoxin production etc. Mycology 65: 1266 - 1273.

6. Applegate, K. L. et al. 1974. Effects of Co-60 gamma irradiation on etc. Mycology 66: 436 - 445.

7. Applegate, K. L. et al. 1974. Daily variations in etc. J. Appl. Bact. 37: 359 - 372.

8. Applegate, K. L. et al. 1976. Production of ochratoxin A by A. ochraceus etc. Appl. Environ. Microbiol. 31: 349 -353.

9. Teufel, P. 1983. Microbiological Aspects of Food Irradiation in: Recent Advances in Food Irradiation (eds P.S. Elias and A.J. Cohen) by Elsevier Biomedical p. 217.

---

9. Irradiated commodities infected with fresh mould spores

Moulds

Moulds grow from tiny spores floating in the air everywhere around us. And when they land on a surface they germinate if the circumstances of moisture, nutrients and temperature are right.

What if?

An Indian research team wondered what would happen if irradiated commodities were infected with fresh spores which could germinate.

They took Indian circumstances as point of departure: you have irradiated your commodity, during transport it was infected with the spores of toxin producing moulds, the storage is poor, your commodity gets moist and moulds get a chance to grow. What will happen? They set out to find out.

They tested a number of commodities: wheat, maize, sorghum and pearl millet were irradiated with 0.75 kGy against insects. Potatoes and onions were irradiated with 0.10 kGy to prevent sprouting.

After irradiation the commodities were heat sterilised and then inoculated with spores from a toxin producing mould. The same was done with unirradiated commodities to compare. This was followed by incubation at 27 EC for 7 days.

Much more toxin formation

In the irradiated commodities they found much more toxin formation than in the controls without irradiation. This was for wheat 45.7 % more toxin, for maize 31.4% more toxin, for sorghum 80.8% more toxin, in pearl millet 66% more toxin, in potatoes 74.4 % more toxin and in onions 84% more toxin (1). This was clearly a general trend and in a follow up research they tried to find out what the cause could be.

Irradiated wheat

They took wheat and irradiated it with a range of different doses and did further exactly as with the first research. And now they found that with an increasing dose there was increased toxin formation. They put their findings in a table which is quite revealing. Here is that table:

Irradiation dose 0 0.50 0.75 1 2 2.5 Aflatoxin B1 358 512 544 556 571 633 Free fatty acids 354 493 532 540 570 599 Fungal weight 18.5 20.2 17.9 18.6 16.3 16.3

The important thing is to realise that all these numbers are quantities. No matter how they are expressed. So let us see what the table tells us.

The tale of the Table

The first and second column together show that with increasing radiation dose the amount of aflatoxin also increases. The fourth column tells us that the dry weight of the mould remained more or less the same. So, the increased toxin production is not caused by increased growth of the mould. The third column is the amount of free fatty acids in the wheat. Column 1 and 3 together show that increased irradiation caused an increase in free fatty acids. So, to put things together: more irradiation gave higher levels of free fatty acids and this resulted in more aflatoxin production (2).

This research is in line with French research that found that irradiation causes the breakdown of fats in free fatty acids, which stimulate aflatoxin production (3).

In other words toxin production by toxin producing moulds is greatly stimulated by the chemical changes in commodities caused by irradiation.

Fake research

What was the reaction from the promoters of food irradiation? The usual one: fake research and attempts to discredit this genuine research. Heat sterilisation had destroyed ‘anti-fungal properties’ in the wheat, they pretended. Most farmers know that this is nonsense. When wheat or other commodities get moist then they get mouldy.

Then there were allegations on the followed procedures. Not too many people are familiar with laboratory procedures, so it easy to suggest all kinds of sinister things. And then last but not least they misrepresented this research in their reviews.

Misrepresentation

The crux of the research was, that there was not only an upsurge in toxin production, but a clear dose relationship: more irradiation gave more toxin.

The review conceded that there was this upsurge in toxin production, but stated this was ‘without any clear relationship to the irradiation dose.’(4) So, now in combination with their own fake research they could pass this genuine research off as a fluke.

What if?

Experience shows that under normal circumstances there is fierce competition among micro-organisms. So, it cannot be claimed that under moist conditions you always will find higher toxin levels. On the other hand it is well documented that in many cases the toxin producers got the upper hand with often fatal consequences. So many factors are involved that nobody can predict anything for a given situation.

But what must be understood is that if things go wrong, then this irradiation disinfestation method aggravates matters. And a disinfestation method that makes things worse is a bad disinfestation method.

Uncontrolled chemical engineering

In addition should be understood that irradiating commodities on a regular basis tends to change their chemical composition in such a way that toxin producers can get easier the upper hand. Because although we don’t know why moulds produce toxins it is a fair assumption that somewhere it gives them a biological advantage.

References

1. Priyadarshini, E. et al. 1976. Aflatoxin production on irradiated foods. Food Cosmet. Toxicol. 14: 293-295.

2. Priyadarshini, E. et al. 1979. Effect of graded doses of gamma irradiation on aflatoxin production by Aspergillus parasiticus in wheat. Food Cosmet. Toxicol. 17: 505-507.

3. Ba, D. et al. 1977. Activite lipolytique et production d’aflatoxines chez Aspergillus flavus. Annls of Microbiol. Inst. Pasteur, Paris 128 B, 87-93.

4. Teufel, P. 1983. Microbiological aspects of food irradiation. In: Recent Advances in Food Irradiation (eds. P.S. Elias and A.J. Cohen) by Elsevier Biomedical p.223.

---

10. Irradiated food and internal bleeding

Illusion

When it was still early days in the food irradiation debate (the 1950s), there was this optimistic idea that you could sterilise food with very heavy irradiation doses and have the food still fresh, wholesome and nutritious. This turned out to be an illusion.

The harsh realities were brought home in a rather dramatic way. In short-term feeding studies no deleterious effects had been found in experimental animals from irradiated food. So, a longevity and reproduction study was set up to appraise the wholesomeness of irradiated beef stored for 6 months at 76EF (25EC).

As rats were used in this trial the diet contained all the vitamins and minerals required in rat diets. One batch of beef had been irradiated with 27.9 kGy and another one with 55.8 kGy. These different batches were used in the diet for different groups of rats to find out whether a double irradiation dose would give a different outcome. All irradiated beef was incorporated into the diets on a 35% dry weight basis.

Dead rats

Despite the fact that this was a longevity study, intended to run for many months, the first rat died on 11th day. Autopsy showed that this rat had died from internal bleeding.

Within 46 days a total of 15 rats had died: 14 male rats and one female. In all cases the cause was internal bleeding.

On the other hand there were no dead rats in the control group of 20 male and 20 female rats. They had received an identical diet with this difference that the beef component had not been irradiated. So, the conclusion was that the bleeding was caused by changes in the beef induced by irradiation.

Vitamin K

As vitamin K plays and important role in blood clotting and bleeding was the problem, the investigation went into the direction of vitamin K.

It had been found that experimental diets for rats do not require vitamin K. This vitamin is normally supplied through bacteria in the gut. So, would supplementation with vitamin K stop the internal bleeding? Another experiment confirmed that this was indeed the case.

From then on all feeding experiments with rats fed irradiated diets have included a vitamin K supplement. And the pretense has been that everything is fine. However, this extra supplementation is a tacit admittance that irradiated food can cause severe vitamin K deficiency.

Reference

1. Metta, V.C. et al. 1959. Vitamin K deficiency in rats induced by the feeding of irradiated beef.

2. J. Nutrition 69: 18-22

11.   Irradiated food = peroxidised food

Peroxidised food means food containing rancid fat and toxic material.

Synthetic diets

When, lipid peroxide formation from gamma irradiated food needed to be measured, researchers resorted to synthetic diets. These were mixtures containing starch with either lard or corn oil or herring oil.

Lard and corn oil are saturated fats and little peroxide developed. But in herring oil, high in unsaturated fats, much peroxide was found after irradiation with doses varying from 1 to 20 kGy. With higher doses more peroxide was formed.

When put in storage, peroxidation continued to the point of total destruction of essential fatty acids. This happened irrespective of the given irradiation dose.

It was concluded that irradiation would severely reduce the nutritional value of food and pollute it with toxic peroxides and other degradation products (1, 2)

Rancid fat

This dim view of peroxidised or rancid fat in food had been expressed many times before from the 1940s onwards in scientific journals on nutrition. No suitable technique had been available then to quantify lipid peroxide formation.

A nutritional journal of 1953 had remarked that rancid fat could provide a tool for studying nutritional requirements of animals under adverse dietary conditions (3).

This paper also speculated on what might be the cause of these adverse effects.

1. the presence of a toxic agent?
2. the hampering of normal fat digestion?
3. the destruction of other nutrients?
4. a change in intestinal bacteria and altered functioning of the intestine?
5. diminished food intake? Or, a combination of these factors? (3)

Quoting from scientific reviews this paper then summed up the nutrients which are partly inactivated or destroyed by rancid fat in the diet. They are: vitamin A and carotene, tocopherol (vitamin E), vitamin D, vitamin K, pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin (vitamin B12), ascorbic acid (vitamin C) and the essential fatty acids. These are linoleic, linolenic and arachidonic acids (3)

A review from 1960 on rancid oils and fats identified peroxides, hydroperoxides, rancid linoleic acid and monomeric cyclic compounds as the toxic culprits. In particular peroxides, hydroperoxides and rancid linoleic acid, as they were lethal to rats (4). Also was mentioned that organic peroxides yielded free radicals capable of causing mutations.

Carbohydrates

A review on food irradiation (5) confirmed that irradiated fats and fatty acids develop peroxides. It included a review on irradiated carbohydrates, which also develop peroxides of various kind. It reviewed irradiated sugar solutions and laboratory mediums and their toxic effects on bacteria and cell cultures. In addition to this, irradiated wheat in animal feeding trials was reviewed. Another review on irradiated foods covered similar ground (6). In both reviews the term radiomimetic was used when referring to the toxic effects from peroxides. It was suggested repeatedly that peroxides could well be only intermediate products leading to final toxic substances.

Radiomimetic effects

Radiomimetic means imitation radioactivity. So, you get the same effects from eating irradiated food for a prolonged time as from being exposed to ionising radiation.

In the case of ionising radiation high energy photons trigger off lipid peroxidation in body tissues. A high radiation dose can result in lethal doses of peroxides. But how could this be achieved with food that is not itself radioactive?

Could peroxides be absorbed by the gut and so enter the body? This indeed could trigger off lipid peroxidation inside the body. There has been a long debate whether or not peroxides could pass the gut wall in the world of nutritional research. Only more recently new light has been shed on this issue.

The glutathione story

The small intestine is lined with a slime layer, which is there for protection. This mucus, as it is called, contains gluthatione, which is part of an enzyme system that dismantles peroxides. A research team was able, using rats, to tap into the flow of lymph that encircles the small intestine. This lymph collects all digested food that is absorbed through the gut wall. So, if peroxides could pass this wall, then they would end up in this lymph flow.

The glutathione concentration in the gut was artificially lowered, while a constant flow of lipid peroxides in the gut was maintained. It was found that at low glutathione concentrations the dismantling of peroxides became incomplete and that peroxides could pass the gut wall. And vice versa: with normal levels of glutathione plus increased amounts of peroxides, again peroxides passed the gut wall and showed up in lymph (7).

So, the glutathione enzyme system, effective as it may be under normal circumstances, can be overwhelmed by a heavy load of peroxides.

This point can be illustrated with radiomimetic effects from irradiated food such as polyploid lymph cells. One experiment was with humans and one with Chinese hamsters.

Experiment with humans

In 1975 the National Institute of Nutrition of India investigated how malnourished people (children) would cope with irradiated food. The wheat component of the diet was irradiated with 0.75 kGy as recommended for grain disinfestation. After four weeks only the first polyploid lymph cells showed up, with a steep increase after six weeks. Then the trial was halted (8).

Experiments with Chinese hamsters

Hamsters fed an irradiated, pelletised breeding diet, were given once a week additional vitamin supplements in their drinking water. Take note: a breeding diet is already extremely rich in nutrients This diet was irradiated with various irradiation doses and from 20 kGy onwards polyploid lymph cells showed up.

Another group of hamsters was fed unirradiated breeding diet plus some diluted hydrogen peroxide. And promptly polyploid lymph cells showed up (9).

Obviously the glutathione defense against peroxides in malnourished children was much weaker than in the pampered hamsters.

Lipid peroxidation

Lipid peroxidation has been implicated in the onset of cancer and in atherosclerosis.

References

1. Hammer, C. T. et al. 1979. The effect of ionising radiation on the fatty acid composition of natural fats and on lipid peroxide formation. Int. J. Radiat. Biol. 35 No.4: 323-332.

2. Wills, E.D. 1980. Studies of lipid peroxide formation in irradiated synthetic diets and the effects of storage after irradiation. Int. J. Radiat. Biol. 37 No.4: 383-401.

3. Greenberg, S.M. et al. 1953. Some factors affecting the growth and development of rats fed rancid fat. J. Nutr. 50: 421-440.

4. Rao, B.Y. 1960. Nutritional aspects of heated, oxidised & polymerised fats & oils. J. Sci. Industr. Res. A19: 430-437 (see Table 3 at 436)

5. Schubert, J. 1969. Mutagenicity and cytotoxicity of irradiated foods and food components. Bulletin WHO 41: 873- 904.

6. Kesavan, P.C. et al. 1971. Cytotoxic and mutagenic effects of irradiated substrates and food material. Radiation Botany 11: 253-281

7. Aw, T.Y. et al. 1992. Absorption and lymphatic transport of peroxidised lipids by rat small intestine in vivo: role of mucosal GSH. Am. J. Physiol. 262: G99-G106

8. Bhaskaram, C et al. 1975. Effects of feeding irradiated wheat to malnourished children. Am. J. Clin. Nutr. 28: 130-135

9. Renner, H.W. 1977. Chromosome studies on bone marrow cells of Chinese Hamsters fed a radiation sterilised diet. Toxicology 8: 213-222.

---

12. Irradiated fruit: health risks

Carbohydrates

Fruits have a high content of carbohydrates, a general name for sugars and starch. To name only two examples: bananas are high in starch and grapes are high in sugar.

Irradiated carbohydrates are toxic

It was found that when purified sugars were irradiated, toxic substances were formed which damaged chromosomes. Chromosomes are tiny strands inside the nucleus of a biological cell and contain the DNA molecule which carries the genetic code. So, damage to chromosomes means damage to the genetic code and this could lead to mutations.

Onion and barley root tips brought into contact with irradiated glucose for 2 hours showed chromosome breakages (1).

Germinating seeds of barley and onions placed in irradiated orange and apple juice for 4 hours showed chromosome breakages (2). Spontaneous chromosome abnormalities in barley are very rare.

Bacteria placed in synthetic nutrient media containing irradiated sugars did not survive or showed mutations (3, 4).

Human cells grown on a nutrient growth medium containing irradiated sugar solutions showed widespread cell toxicity (5, 6).

Human lymph cells brought in contact with irradiated sucrose solutions showed extreme toxicity (7).

Around 1970 two review articles on the toxicity of irradiated carbohydrates (8, 9) expressed concern about the small number of feeding trials with mammals.

Monkey study

One such feeding study, monkeys fed irradiated peaches, exposed symptoms of vitamin C deficiency after about 15 months. This disappeared when additional vitamin C as ascorbic acid was given. The food consisted of 35% irradiated peaches and 65% commercial monkey chow (10). But more studies have been done since the experimental protocol was changed.

Change of experimental protocol

A member of the US Atomic Energy Commission spells this out. E.E. Fowler told a conference on fruit disinfestation by irradiation:

" For the papaya feeding studies, we were successful in breaking a longstanding arbitrary rule by the FDA (Food and Drug Administration) that irradiated foods must be fed to animals at a level of 35% of the diet on a dry-weight basis. As all of you recognise, this feeding level presents an unusual insult to the animals. With respect to papayas, the FDA agreed to a level of 15% wet-weight of the total diet fed as a fresh puree.

The 15% level was arrived at after the US Atomic Energy Commission carried out a 30-day preliminary study to determine the maximum tolerable level for this product in the total diet for the three species of animals to be used, rats, mice and dogs." (11).

Questions

Have you ever tried to feed your dog pawpaw? Dogs are flesh eaters and would not be able to get much nutrition out of it. Why was the feeding trial only 30 days ? This is very short. Also, what is 15% wet-weight? How much water and how much irradiated fruit? And why was this "research" not done by the FDA, but by an Atomic Energy Commission? Why at all did the FDA go along with this bizarre nonsense?

The role of the FDA

An article in NATURE of 1971 throws some light on the FDA.

"FDA called unhealthy for science and scientists

The new report concerned with the scientific activities of the agency, is an almost comprehensive catalogue of possible deficiencies in science management that ranges from its subordination of scientific facts to political and economic considerations, to bad morale among scientists, low productivity, antiquated equipment, skimpy record keeping and even laboratories that are actual unsafe."(12)

It seems that this report made little impact. In 1975 the same Journal reported:

Busting the FDA

Their central allegation is that the FDA is so heavily dominated by industry pressure that its decisions are frequently biased in the industry’s favour. As evidence they cite the "revolving door syndrome" in which top FDA personnel are often drawn from the drug industry and usual return to it.’(13)

It appears the FDA is a corrupted organisation manipulated by vested interests, which in this case is the nuclear lobby.

Fake research

It is obvious that since the experimental protocol was changed we are dealing with fake research. The difference between genuine research and fake research is that genuine research tries to find out what is really happening, while fake research tries to hide what is really happening.

The exaggerations in the old protocol were there to magnify adverse effects in a similar way as drugs are tested.

The differences between a diet containing up to 35% irradiated food on a dry weight basis and a diet with 15% irradiated food on a wet weight basis are enormous. The latter diet will virtually guarantee that no adverse effects will show up.

Some history

In the 1950's and 1960's genuine research found that irradiation as a food technology was wanting.

Since that time no further research grants went to food irradiation and genuine research ceased.

However, the nuclear lobby continued to issue research grants to food technologists to get a foot in the door. Also food irradiation projects were carried out. But there was always a proviso: the nuclear lobby laid down the experimental protocol. So, researchers cannot design their own experiments. And whether or not they agree with the protocol, they are under contract and have to follow it. In other words fake research is contracted out.

To a number of researchers this seems easy money as it is well paid. However, what they often do not realise is that these quasi scientific reports are used for promotional purposes. And, here is the rub, these nonsense reports carry their name as scientist.

Jungle

The result is that anyone who wants to do a search on food irradiation, has nowadays to cut his/her way through a jungle of fake research and misinformation before arriving at the genuine experiments. Then the real picture emerges: a technology that is unable to do what it claims it can do and produces low level toxic food. Over time this toxicity builds up inside your body and results in a steady erosion of your health.

References

1. Moutschen, J et al. 1965. Cytological effects of irradiated glucose. Radiation Botany 5: 23-28.

2. Chopra, V.L. et al. 1963. Cytological effects etc. Radiation Botany 3: 1-6.

3. Chopra, V.L. et al. 1969. Lethal and mutagenic effects etc. Mutation Research 8: 25-33.

4. Aiyar, A.S. et al. 1977. Studies on mutagenicity etc. Mutation Research 48: 17-28.

5. Berry, R.J. et al. 1965. Cytotoxic agent in gamma-irradiated carbohyd. solutions. Int. J. Rad. Biol. 9(6): 559-572

6. Kesevan, P.C. et al. 1966. Cytotoxic etc. human leukocytes. Current Science 35: 403-404.

7. Shaw, M.W. et al. 1966. Effects irradiated sucrose on human lymphocytes. Nature 211: 1254-1256.

8. Schubert, J. 1969. Mutagenicity and cytotoxicity of irrad. foods etc. Bulletin World Health Org. 41:873-904

9. Kesevan, P.C. et al. 1971. Cytotoxic and mutagenic effects etc. Radiation Botany 11: 253-281

10. Blood et al. 1966. Feeding of irradiated peaches etc. Toxicol. Appl. Pharmacol. 8: 247-249

11. Fowler, E.E. 1971. PL 422/1 - p.4 in: Disinfestation of fruit by irradiation. Proceedings of a panel on the use of irradiation to solve quarantine problems in the international fruit trade , organized by the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture and held in Honolulu, Hawaii, US of America, 7-11 Dec. 1970. Vienna, IAEA 1971.

12. Nature 231, June 4 1977, p. 277

13. Nature 258, November 20 1975, p.187

---

13. Irradiated grains: health risks

Toxicity well known

The toxicity of irradiated foods was never a secret. Around 1970 two extensive review articles on this issue had appeared (1, 2). They mentioned researches with human cells.

In one research sucrose solutions irradiated with 20 kGy were added to cultures of human lymph cells. After 72 hours at 37 EC it was found that the lymph cells were inhibited in their cell divisions, that chromosomes (carriers of the genetic code) were grossly damaged and that four times endoreduplication occurred (3).

A similar research was done with irradiated culture medium. Here a batch of culture medium was irradiated with 10 and 50 kGy. Th in two parts, each with a normal set of chromosomes. So, you end up with one large cell with a double set of chromosomes. This situation is called endoreduplication or polyploidy. Its normal level is a fraction of one percent. People undergoing radiation treatment find in general an upsurge of polyploid lymph cells in their blood.

‘Expert’ recommendation

Nonetheless a Joint FAO/IAEA/WHO Expert Committee of 1969 recommended a temporary clearance for irradiated wheat. And yes, further studies were recommended focussing on the possible generation of mutation effects from irradiated wheat. They clearly thought that this would only rubber stamp the given clearance. Else they would have recommended further trials only and additional recommendations would depend on the outcome of these trials. At this stage the National Institute of Nutrition in India stepped in.

National Institute of Nutrition

Indian researchers were well aware that the feeding studies with irradiated food had been carried out with well-nourished animals. But as they realised that in many countries malnutrition is widespread, they wondered how malnourished people would cope with irradiated food. So they researched this with children suffering from kwashiorkor, which is a severe lack of protein.

Feeding experiments:

Children (5)

Ten children were divided in two groups of five. Before the trial started blood samples were taken and examined as the starting point for each child. One group of five children was the control group. The other group was the experimental group. The diets given to the children were identical except for the fact that the wheat for the experimental group had been irradiated with a dose of 0.75 kGy, the dose recommended for grain disinfestation.

After four weeks blood samples were taken of all children and examined. In four of the five children given freshly irradiated wheat polyploid lymph cells were found. Other abnormal cells were also present.

After six weeks again blood samples were taken and a sharp increase of polyploid lymph cells compared to the level at four weeks was found. To protect the children from eventual harm it was decided to halt the trial at this stage. The control children did not have any abnormal cells in their blood during the trial.

It was realised that freshly irradiated wheat could distort reality too much. So, instead of wheat fed within 2 to 3 weeks of irradiation, it was first stored for 12 weeks before it was used in the diet of a new group of five children. This time the polyploid cells showed up for the first time after six weeks.

After the irradiated wheat had been withdrawn, it took 24 weeks before the blood of the children fed irradiated wheat reverted to normal and all abnormal cells had completely disappeared. To verify their results they continued with experimental animals.

Monkeys:

The trial of the children was repeated with the same results: a progressive increase of polyploid lymph cells and a gradual disappearance of these cells after the withdrawal of irradiated wheat (6).

Rats and mice (7, 8, 9, 10)

Here a number of other investigations was done. And so it was found that in animals fed irradiated wheat there were:

• increased polyploid cells in the bone marrow
• increased numbers of intra-uterine deaths
• decreased numbers of germ cells in the testis
• depressed immune response

The reaction: fake trials and foul play

The proponents of food irradiation were enraged. So far they had successfully pretended that yes, there were some adverse affects in animals fed irradiated food, but the irradiation dosages in those trials had been excessive. So, irradiated food would be safe in practice they had asserted. Had they not already been given temporary clearance for irradiated wheat? And now the (Indian) National Institute of Nutrition (NIN) pulled the rug from under them. Their findings indicated clearly that irradiated wheat was not safe.

So, a number of fake trials were carried out with generous amounts of anti-oxidants added. The pretense was that these trials duplicated NIN’s research, while in actual fact the diets were quite different. So, it was suggested that through these fake trials NIN’s research was not good.

In addition almost every trick in the book was used to discredit NIN. "Expert committees" were set up to have a closer look at this NIN research. The first thing they did was to misrepresent and distort NIN’s findings. Then it was pretended that the trials had not been designed well without indicating what was wrong and what design should have been used. Then it was rumored that the NIN data were fraudulent and that NIN had withdrawn them. So, NIN had to declare that they stood by their data and considered them valid.

Perhaps the most silly allegation was that the upsurge in polyploid lymph cells was transient. In fact, the sharp upsurge of polyploid cells with continued feeding clearly indicated that the toxic agents were building up inside the body, nothing transient there.

If anything, then the sorry saga around the research of the National Institute of Nutrition concerning irradiated wheat, shows that the nuclear lobby is hell bent on imposing irradiated food on the population, no matter what.

References

1. Schubert, J. 1969. Mutagenicity and Cytotoxicity of irradiated foods and food components. Bulletin WHO 41: 873-904.

2. Kesevan, P.C. et al. 1971. Cytotoxic and mutagenetic effects of irradiated substrates and food material. Radiation Botany 11: 253-281

3. Shaw, M.W. et al. 1966. Effects of irradiated sucrose on the chromosomes of human lymphocytes in vitro. Nature 211: 1254-1256

4. Kesevan, P.C. et al. 1966. Cytotoxic and radiomimetic activity of irradiated culture medium on human leukocytes. Current Science 35:403-404

5. Bhaskaram, C. et al. 1975. Effects of feeding irradiated wheat to malnourished children. The American Journal of Clinical Nutrition 28: February 1975, pp.130-135

6. Vijayalaxmi. 1978. Cytogenetic studies in monkeys fed irradiated wheat. Toxicology 9: 181-184

7. Vijayalaxmi et al. 1975. Chromosomal aberrations in rats fed irradiated wheat. Int. J. Radiat. Biol. 27 No.2: 135-142

8. Vijayalaxmi et al. 1976. Dominant lethal mutations in rats fed on irradiated wheat. Int. J. Radiat. Biol. 29 No.1: 93-98

9. Vijayalaxmi. 1976. Genetic effects of feeding irradiated wheat to mice. Can. J. Genet. Cytol. 18: 231-238

10. Vijayalaxmi. 1978. Immune response in rats given irradiated wheat. Br. J. Nutr. 40: 535-541

---

14. Irradiated vegetables

Which ones, what for?

Most irradiation research has centered around tomatoes, potatoes, onions, garlic and mushrooms. In tomatoes the attempt was to suppress the decay mould Alternaria. In potatoes, onions and garlic irradiation was meant to inhibit sprouting. And in mushrooms irradiation was supposed to inhibit growth and opening of caps.

Tomatoes

The aim to suppress rotting caused by Alternaria would need more than 3 kGy, while many varieties can only tolerate 1 to 1.5 kGy (1).

Those Australian varieties that could tolerate 2-4 kGy in the green mature stage, underwent pronounced tissue softening. The less mature samples regained practically all of their original firmness within 4 days (2). The problem is that immediately after irradiation the fruits are exposed to mechanical injury because of transport. So, stationary trials only could give a dramatically flattered picture of what the reality would be.

Potatoes

In German research the varieties Bintje and Saturna were irradiated with 0.085 and 0.15 kGy. (8.5 and 15 krad) to inhibit sprouting. Then chips and dried potatoes from these irradiated varieties were stored for 6 and 8 months. They showed a grey discoloration and the chips made from the same batch were darker than chips from unirradiated potatoes.

After 6 months storage more rotting was found in irradiated potatoes than in chemically treated ones (3). Also, rotting was irradiation dose dependent (4).

Japanese research found that irradiation induced browning. This varied with where the potatoes came from and the time lapse between harvest and irradiation. It was recommended to irradiate potatoes 1½ to 2 months after harvest, as this gave the least browning. It concerned the Irish cobbler potato (5).

Polish research found that susceptibility to rotting was increased by irradiation. It concerned the ronda and mila potato variety (6).

Australian research found more rotting in irradiated potatoes after 6 months of storage. It concerned the varieties up-to-date, sebago, sequoia and kennebec. Although the report denied it for the last variety, Table I of the report showed it (7).

The observation was made that irradiation suppressed wound healing in potatoes. This gave microorganisms a longer time to establish themselves resulting in an increased incidence of rotting (7, 8).

After 4 months of storage irradiated sequoias had lost more vitamin C than unirradiated ones (9). Research on different potato varieties established that vitamin C loss after irradiation depended very much on the type of variety (10).

Also, a trend towards breakdown of starch into sugars was noted after irradiation. A sugar content of less than 0.4% (fresh weight) was considered essential for the production of light coloured chips. Only the sebago variety could met this requirement (9).

It was suggested that for domestic consumption a higher sugar content might be acceptable ‘if a total sugar content of 1% were tolerable’(9). Would people accept ‘sweet potatoes’ for every day??

Onions

Onions were irradiated to prevent sprouting. It was found that, depending on the variety, inhibition of sprouting went hand in hand with increased rotting during storage. What seems to happen is that the dying the growing tip where sprouting normally starts, becomes an entry point for microorganisms (11, 12, 13).

Garlic

Garlic tolerates irradiation quite well. There are no problems with rotting as garlic juices kill bacteria and inhibit moulds.

Mushrooms

Mushrooms also tolerate irradiation quite well. Still, irradiation has little to offer over cooling.

Canadian research found that 1 kGy inhibited the growth of cultivated mushrooms and increased storage life. However, taste panels preferred unirradiated mushrooms (14).

American research found that 1 kGy was effective and that higher doses tended to discolour the flesh too much (15).

Other research focused on temperature in combination with irradiation. Mushrooms were irradiated with 0.5 and 1 kGy. Then stored at 4 and 13EC. The shelf life of mushrooms stored at 13EC increased by 2 to 4 days. But the shelf life of mushrooms stored at 4 EC increased by more than 14 days. Moreover, they were superior to those stored at 13EC (16). This shows that temperature regulation is much more effective than irradiation.

This conclusion was already made in the 1970s: ‘for good quality retention, mushrooms should be stored and shipped at temperatures near 32EF (=0EC) and relative humidity of 90%. This is easily and economically done. Under these conditions irradiation does not contribute a significant effect on stem growth and cap opening (1).

References

1. Maxie, E.C. et al. 1971. Infeasibility of irradiating fresh fruits and vegetables. HortScience 6(3): 202-204

2. Lee, T.H. et al. 1968. Effects of gamma irradiation on tomato etc, Radiation Botany 8: 259-267

3. Penner, H. et al. 1975. Food Science & Technology Abstracts vol.7:10J1439

4. Grunewald, T. 1973. Experience in irradiating potatoes, in : Aspects of the introduction of food irradiation in developing countries. IAEA, Vienna 1973 - PL 518/2, pp. 7-11.

5. Tatsumi, Y. et al. 1975. Food Science & Technol. Abstr. Vol. 7: 2J300

6. Fiszer, W. et al. 1986. Food Science & Techn. Abstr. Vol. 18: 9J43.

7. Wills, P.A. 1965. Some effects of gamma radiation on etc. 1. Storage problems. Austr. J. Exp. Agric. & Animal Husbandry 5: 282-288.

8. Sommer, N.F. et al. 1966. Ionising radiation for control etc. Advances in Food Research 15: 147-193.

9. Wills, P.A. 1965. Some effects of gamma radiation on etc. 2. Biochemical changes. Austr. J. Exp. Agric. & Animal Husbandry 5 : 289-295.

10. Murray, T. K. 1983. Nutritional aspects of food irradiation, in: Recent Advances in Food irradiation (eds. P.S. Elias & A.J. Cohen) Elsevier Biomedical Press, Amsterdam, The Netherlands, p. 205.

11. Nair, P.M. et al. Sprout inhibition etc. Radiation Preservation of Food - Proceedings of a symposium - Bombay Nov. 1972. IAEA Vienna 1973. Sm- 166/11, pp. 347-366.

12. Salem, S.A. 1974. Effect of gamma radiation on storage of onions. J. Sci. of Food & Agricult. 25(3): 257-262.

13. Menniti, A.M. 1980. Bio-pathological effects etc. Food Sci. & Techn. Abstr. Vol.12: 6J879

14. Campbell, J.D. et al. 1968. Gamma irradiation mushrooms. J.Food Sci. 33: 540- 542

15. Skou, J.P. et al. 1975. Effects of ionising radiation on mushrooms etc. Food Sci. & Techn. Abstr.Vol.7: 11J1613

16. Kramer, M.E. et al. 1988. Radiation processing mushrooms. Food Sci. & Techn. Abstr. Vol. 20: 10J135

---

15. Irradiation destruction of vitamin C

A scientific fact

Vitamin C, also called ascorbic acid, is rapidly destroyed by gamma radiation in dilute solutions (1). This is confirmed by a table from a review report which shows that ascorbic acid is very sensitive to ionising radiation (2). So, there is no controversy on this point.

However, this destruction is called irrelevant by the proponents of food irradiation. According to them the breakdown product dehydroascorbic acid has practically the same vitamin C activity as ascorbic acid (3). This idea turns out to be old fashioned and wrong.

The reality

According to an authority on vitamin C, both ascorbic and dehydroascorbic acid have biological activity. But these biological activities differ (4). Only ascorbic acid has the typical vitamin C working. The breakdown product dehydroascorbic acid is highly unstable (5) and has no vitamin C working. If through circumstances high levels of dehydroascorbic acid are formed, then it can even damage a number of biological processes and affect health adversely (6).

Confirmation

Ascorbic acid and sodium ascorbate have a detoxifying effect on the liver. This was researched in the 1970s and one research report is here of special interest.

This research concerned the protective effect of ascorbic acid and sodium ascorbate on acute liver toxicity. This toxicity was brought about through the administration by mouth of sodium nitrite plus aminopyrine to rats. Also dehydroascorbic acid was tested, but this did not give any protection (7). So, this research report confirms what is stated in the monography on vitamin C (4).

Vitamin C deficiency

A particular aspect of vitamin C activity was illustrated in a trial with monkeys fed irradiated peaches. Like humans, monkeys do not produce their own vitamin C as most other animals do. They must get their vitamin C from food.

In this feeding trial one batch of peaches was irradiated with a dose of 27.9 kGy and another batch with 55.8 kGy. The differently irradiated peaches were of course for different groups of monkeys. The peaches were canned and stored for 3 months to one year. Then they were included in the diet for the trial monkeys on a basis of 35% of dietary solids. The other 65% was ground Purina Monkey Chow. It is important to realise that this commercial monkey chow contains ample vitamin C.

After about 15 months in the trial monkeys on a diet with irradiated peaches showed symptoms of vitamin C deficiency. After additional supplementation with vitamin C these symptoms disappeared. Control monkeys with non-irradiated peaches in their diet did not show any Vitamin C deficiency symptoms (8).

What does this show? That there was an extraordinary demand for vitamin C inside the monkeys to counter toxicity from irradiated peaches.

Well worth remembering that around 1970 two lengthy review articles on the toxicity of irradiated foods were published including carbohydrates (9, 10).

References

1. Rao, B.S.N. 1962. Radiolysis of ascorbic acid in aqueous solutions by gamma radiation. Radiation Research 16: 683-693.

2. Tobback, P.P. 1977. Radiation Chemistry of Vitamins, table 14, p.213. In: P.S. Elias & 3. A.J. Cohen (eds) Radiation Chemistry of major food components. Elsevier Scientific Publishing Co., New York 1977.

4. Murray, T.K. 1983. Nutritional aspects of food irradiation. P.203 in: P.S. Elias & A.J. Cohen (eds) Recent Advances in Food Irradiation. Elsevier Biomedical Press, Amsterdam, The Netherlands.

5. Lewin, S. 1976. Vitamin C: its molecular biology and medical potential. By Academic Press, London, New York, San Francisco. Chapter 4: Biological activity and potential.

6. Op cit 4 at p.17 and 38

7. Op cit 4 at p.102

8. Kamm, J.J. et al. 1973. Protective effect of ascorbic acid on hepatotoxicity caused by sodium nitrite plus aminopyrine. Proc. Nat. Acad. Sci. USA vol.70, No.3, pp. 747-749.

9. Blood, F.R. et al. 1966. Feeding of irradiated peaches and whole and peeled oranges to monkeys. Toxicol. Appl. Pharmacol. 8: 247-249.

10. Schubert, J. 1969. Mutgenicity and cytotoxicity of irradiated foods and food components. Bulletin WHO 41: 873-904

11. Kesevan, P.C. et al. 1971. Cytotoxic and mutagenetic effects of irradiated substrates and food material. Radiation Botany 11:253-281

---

16.   Irradiation to delay ripening

Bananas

In general, to delay ripening 0.30-0.35 kGy as minimum dose would be required (1). This dose range is from the laboratory where everything is much more under control than in a production environment. It has been established that the location of the fruit in the container determines the dose it gets. The end result is not a container with a uniformly irradiated product. If a minimum dose of 0.30 kGy is needed, then you end up with an actual dose range of 0.30 - 0.65 kGy (2). So, how do bananas cope? It again depends on the variety.

Indian research checked out 5 varieties of commercial importance.

Giant and Dwarf Cavendish could tolerate up to 40 kGy. Fill Basket tolerate up to 0.35 kGy; Red could tolerate up to 0.50kGy and French Plantain could tolerate up to 0.30 kGy (3)

American research found that ‘their banana’ (no variety mentioned) could tolerate 0.50 kGy (1)

Canadian research found that the variety gros Michel from Honduras could tolerate 0.50 kGy and higher and that lower doses had hardly any effect on ripening (4)

So in practice the dose range to delay ripening would be too narrow for successful treatment. Not only that you scramble up your carefully selected and graded product, but you end up with bananas in various stages of ripening within one container. Some bananas got insufficient irradiation and start ripening anyhow, other bananas got the right dosage and are delayed in ripening and again other bananas got over exposed and become soft and mushy and will be severely damaged in transit.

Pears

According to one report pears can in general tolerate a dose of around 1 kGy. But 2.5 kGy would be needed for successful delay of ripening (1).

Bartlett pears irradiated with 1 and 2 kGy resulted in a delay in ripening of 2 days if ripening came with ethylene production. This ripening was then normal, while irradiation with 3 and 4 kGy resulted in abnormal ripening. The pears remained green, failed to soften and were insipid in flavour. Timing was very important as only mature but unripe pears responded well to the treatment. Once ripening had started it continued regardless of irradiation (5).

The Leconte variety from Lahore could still be successfully irradiated when slightly unripe. With 2 and 3 kGy ripening was delayed for 2 or 3 days. With higher doses the surface of the pears began to decay while still green after 11 days (6).

Is a delay in ripening of 2 or 3 days worth the effort? How much time would the irradiation treatment take plus transport to and from the irradiator?

Apples

Apples are irradiated to suppress scald and brown core.

According to one report the maximum tolerated dose for apples is about 1.5 kGy. The suppression of scald requires 1.5 kGy as well. As this would be an overall average dose it is clear that many apples would be unacceptably damaged (1).

According to another report McIntosh, Cortland and Rome Beauty apples showed tissue softening within 24 hours of irradiation with 0.10 kGy.

In McIntosh a dose of 0.50 kGy resulted in some skin injury as hard wrinkled, sunken patches on the green portions of the skin.

The Cortlands had a flat taste lacking their typical flavour and irradiated with 1 kGy resulted in an alcoholic or off-flavour. Also, irradiation results varied according to the time of picking (7)

References

1. Maxie, E.C. et al. 1971. Infeasibility of irradiating fresh fruit and vegetables. HortScience 6(3): 202-204

2. Boag, T.S. 1987. Evidence given to the Standing Committee on Environment and Conservation of the House of Representatives. Hansard p. 2229.

3. Thomas, P. et al. 1971. Effect of gamma irradiation on the postharvest physiology of five banana varieties grown in India. J. food Sci. 36: 243-247.

4. Ferguson, W.E. et al. 1966. The effects of gamma irradiation on bananas. Food Technology 20: 105-107.

5. Maxie, E.C. et al. 1966. Food Irradiation: Physiology of fruits as related to feasibility of the technology. Advances in Food Research 15: 105-145.

6. Sattar, A. et al. 1971. Effect of gamma radiation on post-harvest behaviour of pears. Science & Industry 8(3/4): 330-333

7. Massey, L.M. et al. 1964. Some effects of gamma radiation on the keeping quality of apples. Agric. and Food Chem. 12 (3): 268-274.

---

17. Radiation sterilised diets

A submission to an inquiry

An Australian Government inquiry into food irradiation held from 1987 to 1989 received the following submission from the Walter and Eliza Hall Institute of Medical Research:

‘Laboratory mice at the Institute have been bred exclusively on food sterilised by gamma irradiation since 1969. No teratogenic or oncological effects have been observed which could be attributed to the gamma irradiation treatment. We cannot comment on possible effects on normal life span of these mice.’

Teratogenic concerns malformations and monstrosities of fetuses. "Oncological" refers to tumours.

The clear suggestion of this submission is that irradiated food is harmless. But closer scrutiny shows how this food has been supplemented with massive doses of nutrients.

Closer scrutiny

The aim was to work with germ free mice for scientific research. To this effect their diet was gamma irradiated with 50 kGy. Then the food was used at times ranging from one day to one month after irradiation. The breeding mice were kept for as long as they were reproducing rapidly and then killed. On average this was after 9 to 12 months as compared to a normal lifespan of 2 to 2½ years.

Vitamin E

The diet that was used was a commercial diet which was especially adapted to the circumstances. Normally wheat is one of the major suppliers of vitamin E in the diet. On average, ground wheat contains 11 mg of vitamin E per kg (1). This adapted Barastoc mouse breeder ration on the other hand contained 130 mg per kg. This is more than 10 times the normal amount. Depending on the season it seems wheat could be replaced by rye, barley, oats or grain sorghum. In addition the diets contained also linseed meal, or peanut meal, or rapeseed meal, or safflower meal, or soybean meal. So, no shortage of vitamin E here.

Selenium

A very powerful antioxidant is selenium. Among the best natural sources are fish, muscle meat, and whole grains. We find this back in the Barastoc diet as meat and bone meal or bone and meat meal or fish meal. In addition the added salt contained 0.1 mg selenium per kg salt. Also, the synthetic antioxidant BHT was added to the diet.

Vitamin A

Vitamin A boosts the immune system and helps to prevent cancer (2). The Barastoc diet contained 18000 i.u. per kg.

General observations

In addition there was of course the interaction of all nutrients together.

Correspondence with the Walter and Eliza Hall Institute revealed that ‘the original formulation (of the diet) was based on extensive testing in British laboratories in the 1960's.’ Two staff members did the nutritional monitoring and kept tabs on signs for general ill-health or poor breeding performance. On at least one occasion the manufacturer had to vary the amounts of the natural ingredients.

In other words the diet was especially attuned to counter irradiation damage and to foster breeding performance. And as long as no suggestions are made that this mouse breeding program shows the harmlessness of irradiated food, things are above board.

Normal diets

On the other hand an Indian research from 1976 found that in mice fed for three months wheat irradiated with 0.75 kGy a significant reduction in the numbers of spermatogonia A and B and resting primary spermatocytes occurred (3).

Spermatogonia and spermatocytes are names for developmental stages of primitive male germ cells

This research had used a laboratory diet of which the mineral mixture was in accordance with the Association of Official Analytical Chemists and the vitamin mixture was in accordance with the National Academy of Sciences/ National Research Council (4).

Russian research from 1981 with rats fed for twenty months irradiated food found also a dramatic drop in spermatogonia and on many occasions a complete absence of any formation of sperm cells. In addition they found that many tissues in the testes were sclerotic (5).

This Russian research used the ordinary animal house diet customary in the research institutes of the USSR. The total diet was irradiated either at the recommended dose, or at 1/10 of the recommended dose, or at 10 times this dose. In addition there was of course a control group of rats that received the same diet, but unirradiated. As a result of this experimental set up they found that there was direct dose dependence concerning the severity of the tissue damage and the irradiation dose of the consumed food (4)

In other words when normal animal house diets were used with normal supplementation, then irradiation of the total or part of it resulted in all kinds of adverse effects in the animals.

The art of supplementation

An additional observation is here of interest. Since the beneficial effects of vitamin E became wider known, farmers have started to give their farm animals vitamin E supplements. This has resulted in better quality products such as: reduced lipid peroxidation in meat and fat, milk fat and butter, improved tenderness of meat and improved sensory quality of meat (1).

Not surprisingly the manufacturers of diets for laboratory animals followed suit. This increased the fertility and litter size of the animals and resistance to infections and prevented nutritional diseases. But at the same time this novel approach defeated the purpose of laboratory animals. Laboratory animals are bred and raised for the purpose of being used in models of disease. To make them disease resistant defeats their purpose.

Analyses of the National Institute of Health (Germany) found that on average the standard laboratory animal diet contained roughly 8 mg vitamin E per kg diet. This was routinely supplemented with 22 mg vitamin E to bring it to around 30 mg vitamin E per kg diet. However, nowadays commercial standard rodent diets contain often 60 mg/kg vitamin E.

Wrong baseline

Further research found that 60 mg vitamin E per kg standard animal diet gave maximal protection. It gave the same protection as diets containing 300 mg, 3000mg or 30000mg vitamin E per kg diet. So, if your control animals get already maximal protection, you could come to the conclusion that supplementation of vitamin E does not work, has no effect. This… while vitamin E supplementation has in reality a profound influence in raising resistance against diseases (1).

The increased content of vitamin E over the years and other antioxidants in standard laboratory diets, could be responsible for claims concerning the total absence of any protective effects from antioxidants or free radical scavengers in animal models for various diseases (1).

Conclusion

The Australian radiation sterilised diet, the partly or wholly irradiated normal animal house diets of the 1970s and 80s in India and Russia, and the excessively supplemented German animal house diet of the 1990s illustrate the power and importance of vitamin E and antioxidant supplementation in diets.

References

1. Lehr, H-A. Et al. 1998. Potential effects of dietary vitamin E in laboratory animal diets on results obtained in models of disease; in: Free Radicals, Oxidative Stress and Antioxidants (edited by T. Özben), by Plenum Press.

2. Hill, D.L. et al. 1992. Retinoids and cancer prevention. Annu. Rev. Nutr. 12: 161-181

3. Vijayalaxmi. 1976. Genetic effects of feeding irradiated wheat to mice. Can. J. genet. cytol. 18: 231-238

4. Vijayalaxmi.1978. Immune response in rats given irradiated wheat. Br. J. Nutr..40:535-541

5. Ivanov A. E. and A.I. Levina. 1981. Pathomorphological changes in the testes of rats fed on products irradiated with gamma rays. Byulletin ‘Eksperimental’ noi Biologii i Meditsini 91, No 2 : 233-236. Translated: Plenum Publishing Co 0007-4888/819102-0232

---

18.   Radiomimetic effects from irradiated food 

Radiomimetic effects are similar to radiation effects, but are not caused by radioactivity. To the body radiomimetic effects are equally harmful as radiation effects.

Radiation effects

Sharp drop in lymph cell numbers

The most radiation sensitive cells in the body are lymph cells. A sharp drop In the number of lymph cells has been repeatedly found in patients undergoing radiation therapy and experimental animals exposed to radiation. It appears that even at low radiation doses lymph cells manifest this sensitivity (1).

Inhibition of mitosis

Mitosis is a technical name for biological cell division. First the chromosomes duplicate themselves. They carry the genetic code. Then the two equal sets of chromosomes are pulled apart and a new cell wall is formed between them. This results in two new cells with the same genetic material.

When the mitosis is inhibited, the chromosomes duplicate, but are not pulled apart and no additional cell wall is formed. This results in a cell with a double set of chromosomes. When this is repeated a cell with a fourfold chromosome number comes into being. These abnormal cells are called polyploid. They are very rare.

Polyploid lymph cells occur routinely in patients undergoing radiation treatment. Therefore it was suggested to use their level as a measure of radiation exposure for people accidentally exposed to radiation (4). But there was no clear relation between the level of polyploids and radiation dose. So, polyploids could not be used.

Reproductive organs

The second most radiation sensitive cells in the body are the germ cells in the reproductive organs. Very radiation sensitive are the developmental stages of sperm cells such as spermatogonia, spermatocytes A and B, and spermatids.

Total-body radiation of mice and rats gave after 10 to 20 days depending on the dose, a sharp drop in the number of spermato-gonia, spermatocytes, sperma-tids and sperm (10).

Chromosomal aberrations

A well-known effect of ionising radiation is damaged chromosomes. They can break and re-link with the wrong parts, break and keep in short broken pieces or form rings or bridges or transloca-tions. One of the consequences can be that you end up with the wrong number of chromosomes in new cells. When one or more chromosome are too many or missing, the cells are called aneuploid.

Chromosomal aberrations can happen anywhere in the body and are not limited to the reproductive organs (13).

Radiomimetic effects

Sharp drop in lymph cell numbers

Rat food, hard dried cakes, was gamma irradiated with a doses of 30 kGy and 90 kGy. Rats fed on this irradiated food had a decrease in absolute lymph cell numbers of 15 to 20% within a few days to a few weeks after the feeding began. This effect equals a total body irradiation of about 20 rad (2, 3).

Feeding result: polyploid lymph cells

In 1975 the National Institute of Nutrition of India investigated how malnourished people (children) would cope with irradiated food. The wheat component of the food was irradiated at 0.75 kGy, the dose recommended for grain disinfestation.

After four weeks only, polyploid lymph cells were found in the blood of children on food containing irradiated wheat. After six weeks there was a steep increase of polyploids. At that stage it was decided to halt the trial to protect the children from eventual harm (5).

This trial was repeated with monkeys. And again polyploid lymph cells showed up (6). When the trial was repeated with rats and mice their bone marrow was examined (Bone marrow is the place where blood and lymph cells are formed). Again an upsurge in polyploid cells was found (7, 8).

Chinese hamsters were fed a pelletised dry feed. When this was radiation sterilised polyploid cells showed up in their bone marrow (9).

Feeding result: drop in germ cells

A significant drop in the number of spermatogonia A and B and of resting primary spermatocytes was found in mice fed irradiated wheat. Rats were hardier, feeding irradiated wheat gave only a significant drop in germ cells when the rats were malnourished (8, 11). A third research found that sperm-forming cells were completely absent after rats were fed for 20 months a standard animal house diet containing irradiated products (12).

Chromosomal aberrations

When mice were fed irradiated wheat for 3 months aneuploid cells showed up in their testis (8).

Increased structural chromosomal aberrations such as translocations and bridges were found in developing spermatogonia of young mice weaned from parents fed irradiated wheat (14, 15).

Rats showed a significant increase in dominant lethal mutations after feeding irradiated wheat for 3 months (11). Dominant lethality is caused by structural and numerical chromosomal aberrations.

References

1.  Mathe, G. et al. 1971. Acute irradiation in man: treatment of hematologic disorders. In: Pathology of Irradiation, ed. C.C. Berdjis. By Williams & Wilkins Company - Baltimore, p. 636

2.  Schubert, J. 1969. Mutagenicity and cytotoxicity of irradiated foods and food components. Bulletin WHO 41: 873-886-904

3.  Kesavan. P.C. et al. 1971. Cytotoxic and mutagenic effects of irradiated substrates and food material. Radiation Botany 11: 253-266-281.

4.  Bender, M.A. 1971. Use of chromosome analysis in the diagnosis of radiation injury. IAEA Technical Report Series No. 123, p. 277.

5.  Bhaskaram, C et al. 1975. Effects of feeding irradiated wheat to malnourished children. Am. J. Clin. Nutr. 28: 130-135.

6.  Vijayalaxmi. 1978. Cytogenetic studies in monkeys fed irradiated wheat. Toxicology 9:181-184.

7.  Vijayalaxmi et al. 1975. Chromosome aberrations in rats fed irradiated wheat. Int. J. Radiat. Biol. 27 No.2: 135-142.

8.  Vijayalaxmi 1976. Genetic effects of feeding irradiated wheat to mice. Can. J. Genet. Cytol. 18: 231-238.

9.  Renner, H.W. 1977. Chromosome studies on bone marrow cells of Chinese hamsters fed a radiation sterilised diet. Toxicology 8: 213-222.

10.  Sommers, S.C. 1971. Effects of ionising radiation upon endocrine glands. In: Pathology of irradiation, ed. C.C. Berdjis. By Williams & Wilkins Company - Baltimore, p. 428-431.

11.  Vijyalaxmi et al. 1976. Dominant lethal mutations in rats fed on irradiated wheat. Int. J. Radiat. Biol. 29, no.1: 93-98

12.  Ivanov, A.E. et al. 1981. Pathomorphological changes in the testes of rats fed on products irradiated with (-rays. 0007-4888/81/9102-0232 1981 Plenum Publishing Corporation. Translated from: ‘noi Biologii i Meditsiny, vol.91, No.2 pp. 233-236.

13.  Berdjis, C.C. 1971. Cell. In: Pathology of Irradiation, ed. C.C. Berdjis. By Williams & Wilkins Company - Baltimore, pp. 20-22

14.  Bugyaki, L et al. 1968. Do irradiated foods have a radiomimetic effect? Atompraxis 14, No.3: 112-118 (in French)

15.  Bugyaki L. et al. WHO Technical Reports series No. 451, p. 28. Geneva 1970.

19. The risks of food poisoning from irradiated foods

What are we talking about ?

Most people know that food poisoning is caused by bacteria and so is food spoilage. But food poisoning bacteria are different from food spoilage bacteria.

Food spoilage bacteria

Spoilage bacteria are the Pseudomonas bacteria. Their natural function is to break down proteins of all kind. So, they grow on meat, fish, shell fish, milk products and any substance containing proteins. They cause rotting (breaking down of proteins) and their activity makes them a bit on the nose. They are real stinkers.

Are they dangerous? No, they just stink. But if the conditions are right for Pseudomonas bacteria to grow, then other bacteria could grow as well. So, Pseudomonas stench is a warning flag.

Pseudomonas is radiation sensitive

The stinkers are radiation sensitive (1, 2). A comparatively low dose of 2 kGy destroyed enough of them to double the shelf-life of vacuum packed cuts of sirloin steak to 10 weeks, when kept at 4EC (3). And radiation with 2.5 kGy doubled the shelf-life of chickens to 24 days, when kept at 1EC (4).

Food is also radiation sensitive

The maximum dose meat, fish and poultry can tolerate without getting the typical wet dog smell is 2.5 to 3 kGy (1, 3, 5).

The mentioned sirloin steak irradiated with only 2 kGy had a faint irradiation odour on the day of irradiation. Chickens irradiated with 3 kGy developed detectable changes in taste and odour after 15 to 19 days storage at 0EC (1). These changes in taste and smell are caused by biochemical alterations in the food from ionising radiation.

The practice

In practice irradiation would be carried out at around 2 to 2.5 kGy to reduce the number of Pseudomonas bacteria and to prevent radiation damage of the food from higher doses. But after removal of the warning flag the public would have no way of knowing that the meat was no longer fresh and that it could contain dangerous bacteria.

Food poisoning bacteria

Salmonella bacteria are the dangerous ones. Over 2000 different Salmonella bacteria have been identified. They are all parasites of the gut (6) with optimal growth at 37EC. People get ill from the infection, not from any toxin. Birds are notorious Salmonella carriers. The drip water of frozen chickens can contain Salmonella bacteria, which could infect kitchen sink or bench and then cold food there prepared.

Salmonella is radiation resistant

It turns out that food provides radiation protection. So, for the same Salmonella bacterium different elimination doses are needed depending on the food. For example, one research found that a number of Salmonella bacteria in laboratory broth would need 5 kGy for elimination, but on crabmeat much higher doses were needed (7).

Microbiological plating techniques found that Salmonella bacteria could still be recovered after irradiation with 3 kGy (8). The used plating technique corresponded with a medium level of contamination under practical circumstances. But an enrichment technique corresponding with higher levels of contamination recovered Salmonella bacteria after 9 kGy. And on shellfish the food protection was so good that at least 9 kGy was needed for elimination (8). A number of countries have approved irradiation for up to 7 kGy for Salmonella elimination.

Clostridium botulinum

The other food poisoner to focus on is Clostridium botulinum. There are over 200 different Clostridium botulinum bacteria (9). They are spore forming soil bacteria preferring an environment with little air. When the spore germinates a deadly toxin is released. A few toxic peas can cause illness and death. Canned food that has not been properly pasteurised and food sealed in plastic wrap with little air are candidates for trouble. C. botulinum has been found on meat, fish, fruit, vegetables and milk products.

Spores and toxins radiation resistant

The radiation resistance of botulinum spores varies widely. The spores of one C. botulinum required 47 to 50 kGy (10). The spores of another botulinum required 35 to 37 kGy (11), yet some other spores required much less (12). The toxins are also very radiation resistant: 50 kGy was still insufficient in one case (13) and 73 kGy did the job in another case (14).

Bacterial competition

In heavily contaminated environments (sewage, sludge, rotting food) no botulism toxin was found although botulism spores were present (15). When other bacteria were removed the botulinum spores started often to germinate and produce toxin. Based on this suppression by competitors a Joint Expert Committee on Food Irradiation of 1980 (FAO/IAEA/WHO) recommended irradiation of 2.2 kGy (average dose) to keep sufficient bacteria to suppress toxin formation. But they stipulated that the product should be kept at the temperature of

melting ice as an additional safeguard against botulism (12).

The futility of irradiation

In 1960 similar findings were made. A research on chicken carcasses (4) found that low dose radiation did not achieve a high degree of sterility and that the spores of C. botulinum could grow from 3.3EC onwards. It was concluded that the "necessity to maintain adequate refrigeration is a further limitation of radiation treatment, since the additional cost and inconvenience of freezing the carcasses are small, and the frozen carcasses can be stored for longer periods without loss of quality." This comment sums up the futility of the whole radiation treatment. Irradiation adds to production costs but does not give any return. Also, Salmonella starts to grow from 8EC onwards. This is another reason why ongoing refrigeration is a must.

Conclusion

Food irradiation will be done in the 2 to 3 kGy range to remove Pseudomonas bacteria and because higher doses would cause changes in taste and smell of the food. This low dose is insufficient to control food poisoning bacteria, so ongoing refrigeration is needed., just as if the food had not been irradiated. Hence the futility of the irradiation treatment as it only adds to production costs.

References

1. Coleby, B. et al. 1960.Treatment of meats with ionising radiations. IV. J. Sci. Food Agric. 11: 678-684.

2. Thornley, M.J. 1963. Radiation resistance among bacteria. J. appl. Bact. 26: 334-345.

3. Niemand, J.G. et al. 1981. Radurization of prime beef cuts. J. of food Protection 44: 677-681.

4. Coleby, B. et al.1960. Treatment of meats with ionising radiations. III. J. Sci. Food Agric. 11: 61-71.

5. Hobbs, G. 1967. Toxin production by C. botulinum type E in fish. Microbiol problems etc. Panel Proceedings series, IAEA, Vienna 1967, pp.37-44.

6. Stanier, R.Y. et al. 1964. General Microbiology, McMillan & Co. Ltd., London, p.675

7. Dyer. J.K. et al. 1966. Radiation survival of food pathogen in complex media. Appl. Microbiol. 14: 92-97

8. Quinn, D.J. et al. 1967. The inactivation etc. in: Microbiological problems in Food Preservation by Irradiation. Panel Proceedings Series, IAEA, Vienna 1967, 1-13.

9. Anelis, A. et al. 1962. Comparative resistance C. botulinum strains to gamma rays. Appl. Microbiol. 10:326-330

10. Wheaton, E. et al. 1962. Radiation survival curves C. botulinum spores. J. Food Sci. 27: 327-334.

11. Greenberg, R.A. et al. 1965. Radiation injury of C. botulinum spores in cured meat Appl. Microbiol. 13: 743-748

12. Grecz, N. et al. 1983. Action of radiation on bacteria and viruses. In: Preservation of Food by Ionizing Radiation vol.II. (Eds. Josephson et al.) CRC Press Inc., Boca Raton , Florida, p.179.

13. Skulberg, A. 1965. Radiation resistance of C. botulinum type E toxin. J. appl. Bact. 28: 139-141

14. Frazier, W.C. et al. 1978. Food Microbiology by McGraw-Hill Book Co., New York p.427.

15. Johannsen, A. 1965. C. botulinum type E in foods etc. J. appl. Bact. 28: 90-94.

source: http://www.rag.org.au/modifiedfoods/irradiation.htm 18sep01

If you have come to this page from an outside location click here to get back to mindfully.org