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Triphenyltin (TPT):
Evaluation of Pesticide Residues in Food

FAO Meeting Report No. PL/1965/10/1 WHO/Food Add./27.65 1oct65

The content of this document is the result of the deliberations of the Joint Meeting of the FAO Committee on Pesticides in Agriculture and the WHO Expert Committee on Pesticide Residues, which met in Rome, 15-22 March 19651

Food and Agriculture Organization of the United Nations World Health Organization 1965

1 Report of the second joint meeting of the FAO Committee on Pesticides in Agriculture and the WHO Expert Committee on Pesticide Residues, FAO Meeting Report No. PL/1965/10; WHO/Food Add./26.65

TRIPHENYLTIN COMPOUNDS

Chemical name
Triphenyltin acetate 		Triphenyltin hydroxide
Synonyms
Fentin
Empirical formulae
C20H18O2Sn 			C18H16OSn
Structural formulae
		

 

BIOLOGICAL DATA

Biochemical aspects

After ingestion of triphenyltin by cows or sheep, the compound is largely excreted with the faeces (Bügemann et al., 1964; Herok & Götte, 1961). Three sheep given 10 mg daily of 113Sn-triphenyltin acetate for 20 days were killed respectively 28, 52 and 218 days after the beginning of the treatment. 113Sn was found in the milk (average concentration 0.0017 ppm) during the treatment but 17 days after withdrawal of the compound its concentration in the milk was near detectable limits. Tin was present in the milk in at least two forms other than triphenyltin acetate. During the treatment, the concentration of 113Sn in the blood and in the wine were 2.9 µg/l and 7.5 µg/l respectively. In the sheep killed at 28 days, liver, kidney, lungs, pancreas, gall-bladder and brain contained a greater amount of 113Sn than other organs. After 218 days the amount of 113Sn found in the liver was still greater than in other organs (Herok & Götte, 1961).

Work on rats given 113Sn-triphenyltin showed that absorbed triphenyltin was rapidly distributed through the tissues of the body including the brain. Triphenyltin was eliminated relatively slowly and it could be detected in the brain 38 days after a single dose (Heath, 1963).

In vitro studies have shown that triphenyltin inhibits oxidative phosphorylation by isolated liver mitochondria and the adenosine triphosphatase activity of brain microsomes (50% inhibition by concentrations of 1 × 10-6M and 1 × 10-5M respectively) (W. N. Aldridge, quoted by Stoner, 1965).

The oxygen consumption of cerebral slices of brains from rats in a moribund condition due to triphenyltin was within normal limits (J. E. Cremer, quoted by Stoner, 1965).

Studies on the effect of tin compounds on plants are in progress in several laboratories. It has been shown that in the presence of light and air several by-products of triphenyltin acetate can be formed, such as diphenyltin and finally insoluble tin (Kroller, 1960). The tin content from the leaves can be transferred to the ground. However, when 113Sn-triphenyltin acetate or hydroxide was applied to potato foliage, no translocation of 113Sn from leaves to tubers could be demonstrated above the limit of determination of 0.0001 ppm. Tin could be detected in the haulm, where the percentage of the original compound decreased for 20 days (Anon., 1964). It has also been shown that triphenyltin has no systemic action when applied to celeriac and sugar-beet (Herok & Götte, 1963).

Acute toxicity

Animal 		Route 		 LD50 mg/kg 	References
Mouse 		Oral 		 81-93.3 	Anon., 1961
Mouse 		Intraperitoneal  7.9 		Stoner, 1965
Rat 		Oral 		 136* 		Klimmer, 1964
Rat 		Oral 		 491** 		Stoner, 1965
Rat 		Intraperitoneal  13.2 		Klimmer, 1964
Rat 		Intraperitoneal  8.5 		Stoner, 1965
Guinea-pig	Oral 		 21 		Klimmer, 1964
Guinea-pig 	Intraperitoneal  5.3 		Klimmer, 1964
Guinea-pig 	Intraperitoneal  3.7 		Stoner, 1965
Rabbit 		Oral 		 30-50 		Klimmer, 1964
Rabbit 		Intraperitoneal  10 		Klimmer, 1964

* In tylose. ** In arachis oil.

In all species the main action of these organotin compounds is thought to be on the central nervous system.

Cat. Intravenous administration of triphenyltin acetate at a dose of 1 mg/kg produced an increase in blood-pressure and a short interruption of respiration followed by stimulation of respiration and clonic contractions of the limb muscles. Repeated administration of 1-2 mg/kg at 20-60 minute intervals led to arterial hypotension. A decrease in the effect of noradrenaline on blood-pressure was also found. Death took place after 4-14 mg/kg of triphenyltin acetate from paralysis of the respiratory centres (Tauberger, 1963).

Short-term studies

Rat

(a) Triphenyltin acetate. Groups of 20-25 rats given triphenyltin acetate by stomach-tube at doses equivalent to 5, 10, 25 and 50 ppm for 107-170 days. At 50 ppm 70% of the rats died in 7.49 days. Nervous symptoms, as well as blood, urinary or histopathological changes were not observed at these lower dose levels (Klimmer, 1964).

In other experiments on rats no deaths occurred during a 10-week period on 200 ppm triphenyltin acetate. These rats were then put on a diet containing 300 ppm and 5 out of 6 rats died after a further 117-168 days (Stoner, 1965).

Groups of young rats, 10 of each sex, were given respectively 0, 5, 10, 25 and 50 ppm of triphenyltin acetate for 12 weeks. Decrease of food intake and growth inhibition were recorded at 50 ppm as well as growth inhibition in males at 25 ppm. At 10 ppm and above the number of leucocytes in the blood was decreased and at 50 ppm the haemoglobin was reduced. At the highest level there was a decrease of the organ/heart weight ratio for the pituitary and pancreas in all animals and uterus and ovary in the females. The same ratio for the thyroid was decreased in all the females as well as in the males at 25 and 50 ppm. The water content of the brain in males and spinal cord in females was significantly increased but only at 50 ppm. No histological studies are yet available on this material (Verschuuren & van Esch, 1964).

(b) Triphenyltin hydroxide. Groups of 10 or 20 rats of both sexes were given 0, 5, 20, 50 and 100 ppm of triphenyltin hydroxide for 28 days. Food intake and body growth were depressed at 20 ppm and above. Death-rates were 9/10 at 100 ppm; 9/20 at 50 ppm and 1/20 at both 20 and 5 ppm (van Esch & Arnoldussen, 1962).

Groups of 10 rats of each sex were given respectively 0, 5, 10 or 25 ppm of triphenyltin hydroxide in the diet for 12 weeks. The food intake was comparable to the controls. The females showed growth inhibition after six weeks but they recovered in spite of continuing treatment. Growth in males was comparable to the controls. In the females blood leucocytes were decreased. No significant changes in water content were found in nervous tissues. At 25 ppm decrease of the thyroid weight was noticed (Verschuuren et al., 1962). In a similar experiment in which 10 rats of each sex were given 50 ppm of the same compound, the following features were noticed: decreased food intake, growth inhibition in both sexes, decrease in weight of the thyroid, pituitary, uterus, ovary, prostate and pancreas as well as decrease of haemoglobin and leucocytes. The water content increased in the spinal cord but not in the brain. No histopathological details of these studies are yet available (Verschuuren & van Esch, 1964).

Guinea-pig

(a) Triphenyltin acetate. In one experiment, 50 ppm led to the death of all of nine animals in 17-31 days. In other experiments only a group of 5 guinea-pigs given 1 ppm for 392 days did not show an increased mortality rate. Even at 1 ppm food intake was reduced. When death occurred it was preceded by loss of weight and generalized weakness (Stoner, 1965). Neither in these experiments nor in others (acute and short-term) in which guinea-pigs and rats have been treated with triphenyltin has a significant increase in the water content of the central nervous system been found nor the characteristic histological lesion in the white matter produced by triethyltin (Magee et al., 1957) been seen (Stoner, 1965).

In other experiments, groups of guinea-pigs, 10 of each sex, were given respectively 5, 10, 20 and 50 ppm of triphenyltin acetate for 12 weeks. In all groups, but for the males given 5 ppm, growth inhibition was obvious. At the end of the treatment no animals at 50 ppm were alive; in the other groups the survival rates were: 20 ppm, 8/10 males and 8/10 females; 10 ppm, 9/10 males and 10/10 females; 5 ppm, 9/10 males and 10/10 females. In all the groups the Hb content of the blood as well as the total number of leucocytes and erythrocytes was decreased in comparison to untreated controls. Also basophilic "stippling" in erythrocytes was noted and only in the experimental group. At 20 and 50 ppm a significant increase of brain water was noticed (Verschuuren & van Esch, 1964).

(b) Triphenyltin hydroxide. Groups of 3 males and 3 females were given 0, 1, 2.5, 5 and 20 ppm of triphenyltin hydroxide for three weeks. No changes in the growth rate nor the water content nor histology of the nervous system were observed (Verschuuren & van Esch, 1964).

Groups of 10 males and 10 females were given 2.5, 5, 10 or 20 ppm for 12 weeks. Growth inhibition was observed at the highest dose-level. Hb and total leucocytes were decreased in all groups. The organ/body-weight ratio of spleen, thymus, uterus and testes were decreased and those of kidney and brain were increased, but no increase in the water content of the nervous system was observed. In another experiment in which 10 animals of each sex were given 50 ppm of triphenyltin hydroxide, all the animals died within six weeks and showed a significant increase of brain weight and water content of the brain and spinal cord. No histological details are yet available on these studies (Verschuuren & van Esch, 1964).

Long-term studies

No long-term experiments are so far reported.

Comments on experimental studies reported

Triphenyltin appears to be a non-systemic fungicide for celeriac, sugar-beet and potatoes. Although some toxicological data are now available they are insufficient to establish a no-effect level in a sensitive species of animal. There are many unresolved problems concerning this compound notably concerning its action on the nervous system. The meeting was informed that work on these problems was in progress. Until detailed reports of these studies are to hand no statement can be made about the acceptability of these compounds to man.

REFERENCES

Anon. (1961) Unpublished data from Sankyo Co., Ltd.

Anon. (1964) Unpublished data from Philips-Duphar

Brügemann, J., Berth, K. & Nieser, K. H. (1964) Zbl. Vet. Med., 11, 4

van Esch, G. J. & Arnoldussen, A. M. (1962) Unpublished report of the National Institute of Public Health, Utrecht, Tox 39/62

Heath, D. F. (1963) Radiation and radioisotopes applied to insects of agricultural importance, IAEA, Vienna, p. 185

Herok, J. & Götte, H. (1961) Symp radioisotopes in animal biology, Mexico City, p. 177

Herok, J. & Götte, H. (1963) Internal J. Appl. Radiation and Isotopes, 14, 461

Klimmer, O. R. (1964) Zbl. Vet. Med., 11, 29

Kroller, E. (1960) Dtsch Lebensmitt Rdsch., 7, 190

Magee, P. N., Stoner, H. B. & Barnes, J. M. (1957) J. Path. Bact., 73, 107.

Stoner, H. B. (1965) To be published

Tauberger, G. (1963) Med. Exp., 9, 393

Verschuuren, H. G. & van Esch, G. J. (1964) Unpublished report of the National Institute or Public Health, Utrecht

Verschuuren, H. G. van Esch, G. J. & Arnoldussen, A. M. (1962) Unpublished report of the National Institute of Public Health, 161/162

source: http://www.inchem.org/documents/jmpr/jmpmono/v065pr42.htm 12jan03

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