GM Peas: Dangerous Immune Response In Mice

Reprinted with permission from Spilling the Beans Newsletter, Nov/Dec 2005, by Jeffrey M. Smith, Author of Seeds of Deception

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Part 2 of 4: GM Food Safety Assessment

Researchers checked the sequence of the kidney bean gene after it was inserted into the pea’s DNA. It hadn’t changed during the insertion process, but this is not always the case. Genes inserted into soybeans and corn, for example, were mutated, fragmented or truncated, and several appeared to rearrange over time. Remarkably, safety assessments don’t always require that the transgene’s sequence is determined. In the US, for example, gene sequencing is not part of the approval process.

If a gene’s sequence changes, it might create proteins with the wrong amino acids. But analyzing the sequence of amino acids is also not required. According to Bill Freese, a research analyst at Friends of the Earth, “At present, the standard practice is to sequence just 5 to 25 amino acids,” even if the protein has more than 600 in total. They assume that the rest are fine. Most of GM foods on the market have never had their novel proteins sequenced. The GM peas, however, were checked. The protein produced in the peas did have the same amino acid sequence as the original in the beans.

Scientists at the John Curtin School of Medical Research in Canberra tested the peas on mice, to see if they elicited an immune or allergic response. Groups of mice were fed a commercial diet and also given GM peas, non-GM peas or beans, twice a week for four weeks. After the feeding period, the mice were tested with a battery of immune response tests. Reactions were elicited only in mice that were fed GM peas. Specifically, injections of the GM protein into the footpad resulted in significant swelling; when introduced into the trachea, it caused mild lung damage and tissue inflammation (similar to asthma in humans). Lymph nodes also responded to the presence of GM protein. The researchers did not check for allergies, per se, but used tests that they say are predictive of allergenic sensitivity.

Simon Hogan, the lead researcher for the study, said, 'The study is fairly conclusive.” He added, “These types of assays are commonly used in medical research.' They have not, however, been used in safety assessments for GM foods on the market. Even though experts with the Food and Agriculture Organization and the World Health Organization (FAO-WHO) recommend using animal studies to test for allergies, no government actually requires it, and it is almost never done.

According to immunologist Ricki Helms, who has served on several expert panels examining the potential allergenicity of GM foods, 'Animal models can contribute to the evaluation of allergenicity but cannot offer absolute certainty.' This lack of certainty is a common justification by industry scientists for why they don’t use animal allergy studies as part of their assessments. The two methods that they prefer, however, also lack certainty.

In the first method, the transgenic proteins are put into test tubes with digestive enzymes and acid to measure how quickly they are broken down. This test is based on the fact that allergenic proteins often—but not always—break down slowly in the stomach and intestines. The problem is that test tube studies do not accurately predict what happens inside humans. And even if they did, a protein that is broken down quickly may still cause allergies. Thus, potentially harmful allergenic proteins can pass this test.

In the other method, researchers search databases to see if the amino acid sequences of the transgenic protein are similar to known allergens. This method also offers no guarantees—not all allergenic sequences have been identified and allergenic proteins can certainly pass this test as well. In spite of the shortcomings of these two methods, the FAO-WHO recommends them as part of the assessment and offers specific criteria for each. Regulators can ignore those recommendations. The GM soy, corn, and papaya on the market, for example, fail the FAO-WHO criteria. GM pea developer TJ Higgins told me that when his peas were evaluated for protein stability and amino acid similarity, they were 'borderline.'

In addition to creating an immune response in mice, GM peas also increased their immune system's sensitivity to other substances. For example, mice fed the non-GM peas showed no response to egg albumin. The GM-fed mice did have an immune reaction to the albumin, as well as to three other substances tested.

The ability of one food to increase the sensitivity to other foods is called an 'adjuvant' response. It suggests that humans fed GM peas might develop allergic or immune responses to a wide range of other foods. According to Judy Carman, an epidemiologist and the director of The Institute of Health and Environmental Research in Australia, 'If a GM food was introduced onto supermarket shelves and caused an immune reaction, it would be very difficult to find the culprit, particularly if it caused reactions to other, different foods, as this GM pea was found to do.' As you probably guessed, adjuvant testing is not part of any normal GM food approval process.

Independent researchers did test a GM product both for immune and adjuvant responses using mice.[2] They tested one type of Bt-toxin (Cry1Ac) found in GM cotton, which is similar to Bt toxins produced in several varieties of GM corn (Cry1Ab). Like the alpha-amylase inhibitor in peas, Bt toxins kill pests. Not only did the Cry1Ac produce a significant immune response, it elicited an adjuvant response as well.

Another study showed that Bt toxins in spray form caused antibody responses and allergic symptoms in farm workers and others.[3] Taken together, these studies overturned several safety assumptions. In spite of claims to the contrary, Bt is not fully destroyed during digestion, it is bioactive in mammals (including humans), and current safety assessments are inadequate. By the time this research was done, Bt crops were already planted on millions of acres. Withdrawing them will apparently require more evidence of human harm.

Another assumption used often by the biotech industry is that cooking their GM crop will destroy its potential to create allergies. Cooking can change the protein’s structure, or 'denature' it. Proponents have claimed that when Bt is denatured, it is no longer effective as a pesticide and will therefore no longer be allergenic. The GM peas were boiled for 20 minutes. After cooking, the alpha-amylase inhibitor was denatured and was no longer effective in protecting against weevils. Industry assumptions notwithstanding, the cooked pea protein still caused an immune response in mice.

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Spilling the Beans is a monthly column available at the website Responsible Technology

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