Is the Bt Corn Allergy Real?

Anonymous Email Question with Response 4mar04 

Dear Mindfully.org,

I want to comment on the Philippine corn story.

There was a widespread illness of some sort in a volcano mountain village in the Philippines, and the villagers suspect it has something to do with GE corn. How much can be made of it with insufficient evidence, and what might be going on?

Allergy?—nope, epidemic allergy like this doesn't happen—it would be like a whole airliner all getting allergic to cocktail peanuts at the same time. People who live on the flank of a volcano and say they smelled something before they got sick? That sounds like it came from the earth. There are spots in California where the trees are dying overlying magma still thousands of feet below, just because of gases seeping. At 7,200 feet the air is thinner meaning you have to breath harder to get enough oxygen and it takes less hydrogen sulfide to make you sick—hydrogen sulfide is actually more toxic than carbon monoxide. Plain old epidemic illnesses from viruses or bacteria? Could be. How much activism before you have facts? Hard to argue for good, honest, uninterested science in the public interest if you jump onto this without any skepticism; hard to argue for the precautionary principle if you don't show some caution yourself. But if—just say IF—the villagers are right about the corn, then what we have is not Bt toxin causing the problem but some metabolic change in the corn, perhaps brought on by elevation or some other unknown factor, which has caused a new toxin to be produced. In other words, if it makes any sense at all it would be sort of like the L-tryptophan disaster where a novel, unsuspected toxin is produced by a GE organism.

I don't actually think this is very likely. If the horses ate this stuff, they didn't think the smell was in the corn, so if there was a smell as it says in this story, I'll bet on subsurface geology and venting gases. But the story can't be added up as mass allergy so don't push it that way. This doesn't make sense as an allergy story.

I think you should wait until more facts come out.

Sincerely,
A Reader

Dear Reader,

Thank you for asking this question. 

The crucial issue the Philippine report raises is the need for more open and independent scientific research on GM crops since we know that Monsanto and friends are not going to report any kind of negative evidence—just the opposite—they will suppress it at every turn. Just look at Pusztai's and Chapela's celebrated crucifixion for their negative evidence. And remember that Monsanto claimed that PCBs were just fine for humans and the environment and so mass produced millions of pounds of PCBs for nearly 50 years.

Michael Hansen of Consumer's Union testified to EPA on StarLink about the potential for corn dust allergy in farm workers. Hansen suggests that there is scientific evidence that occupational exposure to grain dust can lead to allergic symptoms, with the classic case being bakers' asthma as reported by Baur in 1998. Hansen says that more recent studies also implicated corn dust in respiratory dysfunctions including acute respiratory inflammation, according to Park et al. (1998) and Wohlford-Lenane et al (1999) and in a glove-lubricant-powder derived allergy (Crippa et al., 1997). Thus, corn dust (I think this includes the pollen) can clearly convey allergens, and the pro-delta-endotoxin is potentially allergenic, so there is ample evidence to be concerned about occupational exposure to grain dusts, especially corn.

Hansen further states: "Noteworthy is that, while the authors of that study found that farm workers had skin reactions and IgE antibodies to Bt spray, they could not link any respiratory symptoms to the occupational exposure. However, this could be a result of the fairly low levels of Bt that the farm workers were exposed to. The concentration of delta-endotoxin in the Bt crops, particularly corn, is between one to two orders of magnitude higher compared to Bt sprays. That's why the insect resistance management strategy is called the "high dose" strategy. Furthermore, the concentration of the Cry9C protein in the seed is one to two orders of magnitude higher than the concentration of Cry1Ab or Cry1Ac in corn and cotton, respectively-18.6 µ/gm (kernel) for Cry9C vs. 1.4 µ/gm (kernel), 0.19-0.39 µ/g (grain), and 1.62 µ/g for Cry1Ab-Bt11, Cry1Ab-MON810, and Cry1Ac, respectively (EPA, 2000: pg. IIC17). So, the concentration of Cry9C in corn dust could conceivably be 2 to 3 orders of magnitude higher than they level of endotoxin found in foliar Bt sprays. So, the Bt crops have far higher levels of endotoxin in the grain and leaves than do the foliar Bt sprays. Furthermore, while farm workers are exposed to the foliar Bt sprays, workers in mills or other areas where grains are being processed would be exposed to grain dust and so could conceivably be exposed to far higher quantities of the Bt endotoxin than a farm worker would."

What we don't know about the Philippine/Syngenta's Bt176 GE corn is the concentration range of the Cry1Ab endotoxin in the Bt pollen. But the Norwegian Institute for Gene Ecology indicated finding a concentration of the Cry1AB Bt-toxin from 0.014 µ to 0.9 µg in the Bt corn kernels. So could the 39 local residents be reacting to Bt corn dust and Bt pollen containing the Cry1AB Bt-toxin? If not, why would their blood contain detectable concentrations of the IgA, IgG, and IgM antibodies in the blood samples, indicating an immune reaction to GE maize pollen and perhaps the GE corn dust as others have previously suggested.

I know Drs. Marvin Legator at UT Medical Branch-Galveston and Kaye Kilburn at UCLA Med school who have both worked on hydrogen sulfide symptoms in various communities exposed to this neurotoxic gas. It's highly toxic for sure. I don't recall them describing an increase in concentrations of the IgA, IgG, and IgM antibodies in the blood samples, but hydrogen sulfide gas attacks the red blood cells and binds up the oxygen-carrying capacity of the RBCs by going after the cytochrome oxidase enzyme system, which is crucial to life. Hydrogen sulfide injures and kills by combining with the iron (by forming an iron sulfide) in a crucial enzyme that lets our cells use oxygen. Basically H2S shuts down cellular respiration before antibody formation could occur, if that was a mechanism at all that would be triggered. So I am not aware of that H2S would induce changes in the antibody concentrations as reported in the Philippine study.

General information about the toxicity of hydrogen sulfide gas/rotten eggs

Hydrogen sulfide is similar to cyanide in toxicity. It interferes with the enzyme cytochrome oxidase, which is necessary for cells to make use of oxygen. How does H2S enter the body? There are three routes: inhalation—from breathing vapors absorbed through the lungs; oral—from ingestion of contaminated substances (especially water), absorbed through the intestinal tract; and skin—from contact with contaminated substances (such as air), absorbed through the skin. The main route of absorption of H2S is through inhalation.

Animal studies of H2S show widespread distribution in the body after inhalation exposures, with a selective distribution to the brain stem compared with other areas of the brain. Research in animals has identified more than forty health effects of H2S. Data demonstrates that numerous similar health effects occur in human exposure to H2S. Metabolism takes place by three pathways: oxidation to sulfate, methylation, and reaction with metallo—or disulfide—containing proteins. This last appears to be the main pathway for toxicity.

Human populations most sensitive to H2S are assumed to be the fetus (animal data only), children, persons with heart disease, individuals with asthma, individuals who metabolize organosulfides differently, and persons consuming alcohol.

Medical information about H2S toxicity and chronic exposure at low level concentrations

Hydrogen sulfide's toxicity at the 800-1,000 parts per million level (and higher) is well documented as being instantaneously lethal to exposed human beings. Hydrogen sulfide works by rapidly interfering with the brain's respiratory command center (sending nerve signals to the lungs) and poisoning the blood's oxygen carrying ability, but long-term, low-level or chronic exposures have been generally considered to be less toxic and less harmful.

The driving regulatory assumption has been that if an exposure to H2S is not fatal, there are few, if any, lasting health effects. But that assumption is medically outdated. Four public health scientists-including Kaye Kilburn, Ph.D., University of Southern California School of Medicine, and Marvin Legator, Ph.D., University of Texas Medical Branch-Galveston-participated on an H2S panel at the American Public Health Association's annual meetings November 11, 1997, in Indianapolis, Indiana, to present and discuss groundbreaking research demonstrating the extraordinarily toxic nature of H2S at the chronic, low levels to which communities across the nation are routinely exposed. These public health findings support the thesis that exposure to hydrogen sulfide, even in extremely low concentrations, can cause lasting damage to the nervous system.

Dr Kilburn has been conducting research on the health effects of exposure to H2S for many years. Describing a new study, he unequivocally stated at the conference that "H2S poisons the brain, and the poisoning is irreversible". Demonstrable symptoms of chronic exposure include pronounced deficits in balance and reaction time, as well as such ailments as dizziness, insomnia, and overpowering fatigue.

I don't think that H2S gas—as toxic as it may be—seems likely to explain the respiratory systems in the 39 or so Philippine people. Could the villagers have been exposed to both H2S gas and Bt pollen? Well one more point is that hydrogen sulfide is also lethal to plants and so I wonder if the Bt corn plants would survive as well in the presence of H2S unless the concentrations were very low.

This week Mae-Wan Ho in the UK is reporting on an inquiry over the strange deaths of twelve dairy cows in Hesse, Germany apparently after being fed Syngenta's Bt176 GM maize. It was also reported that some other local cows had to be slaughtered due to mysterious illnesses. We can only speculate and that does not prove anything.

We do have a small amount of evidence that GE crops may cause harm. Back in 1999, Pusztai et al. reported that GE potatoes engineered with the snowdrop lectin adversely affected every organ system of young rats, in particular, it made their stomach lining twice as thick. Scientists in Egypt found similar effects in mice fed a Bt potato. Several years earlier, the US FDA already had data showing that rats fed a GE tomato with an antisense gene to delay ripening developed holes in their stomach. Add to that the report from Aventis/Bayer which showed that glufosinate-tolerant T25 GE maize killed twice as many broiler chickens compared to non-GE maize, and a host of anecdotal evidence that livestock, wildlife and lab animals avoid GE feed when given the choice, and failed to thrive or died when forced to eat it.

Volcanoes also emit sulfur dioxide and several other sulfur compounds. But again I have not heard evidence of increased antibody levels in the blood of persons exposed to SO2, but it would cause respiratory harm depending on the gaseous concentrations. Did the villagers suffer from exposure to the Cry1AB Bt-toxin in the Bt corn dust and Bt pollen over a short period of time? I guess we will have to wait for more evidence to find out what caused the respiratory effects on the villagers, if it can be known at all.

Best regards,
Mindfully.org