Titel: Problems with StarLink Allergy Study
Datum: 18 juni 2001
Bron: CropChoice News
Via: Biotech Activists, biotech_activists@iatp.org, 18 juni 01

Environmental group Points out Problems with StarLink Allergy Study

(June 18, 2001 --CropChoice news) -- The environmental organization Friends of the Earth has pointed out potential problems with tests that cleared StarLink of causing allergic reactions in 17 people who ate yellow corn products that might have contained the transgenic variety.

The Centers for Disease Control tested the people after they had complained of rashes, anaphylactic shock and other reactions after eating corn products. But, the allergy test results showed that the protein in StarLink - Cry9C - did not induce antibodies in their blood, meaning that it was not allergenic.

One of the participants, Grace Booth of California, questioned the validity of the tests. She told The Washington Post: "Everything else I ate in the 72 hours before I got so sick, I've eaten again with no problem. Frankly, I don't trust the tests."

Aventis CropScience engineered StarLink, which has approval only for livestock consumption yet contaminated the human food chain last year, to express Bt, a biological insecticide. Besides the possibility that StarLink might cause allergies, scientists and environmentalists have pointed out that engineering Bt into corn, cotton, and other crops could lead to insects developing a resistance to it.

Friends of the Earth has pointed to three reasons whythe tests that the FDA and Centers for Disease Control conducted could have missed allergic reactions to the StarLink Cry9C protein:

"1) The group that was tested is too small to be representative of the potentially affected population;

2) The FDA used a questionable testing method; and

3) Special risks to infants, children and farm workers were not taken into consideration.

These issues, first raised by independent allergy experts on the EPA's StarLink Scientific Advisory Panel (SAP), must be addressed before the EPA decides whether or not to approve StarLink corn in the food supply.

Group Tested for Allergic Reactions is Too Small; Hundreds of Allergy Reports Not Investigated

The FDA has tested only 18-20 people, a handful of self-reported cases. Because millions of people have been exposed to StarLink, negative results from just 18-20 cases only show that more testing is needed. This is why the SAP called on the FDA to widen the scope of the investigation by collecting additional corn-related allergic complaints from the medical and allergy communities, and testing farm workers exposed to StarLink.

The FDA has not only disregarded these recommendations, it has also ignored hundreds of allergy reports from the food industry. Food company data submitted to the FDA show a dramatic increase in allergic complaints after the first disclosure of StarLink contamination (Kraft Taco Bell taco shells) on Sept. 18, 2000. The food industry says these reports are media-driven. But Dr. Hugh Sampson, a leading allergist who served on two expert StarLink panels, points out that because normal corn is rarely allergenic, few people would have suspected StarLink as the cause of their allergic reactions until news of the contamination broke (SAP Transcript, p. 461). In one set of data covering the two months after StarLink contamination first became public:

210 consumers who reported allergic reactions to food companies blamed corn products + This is over 5 times the number of corn-related complaints reported over the preceding 2 years + 74 of these people (35%) sought medical treatment with a physician + 20 (10%) sought medical attention in an emergency room

FDA Uses Flawed Test for Allergic Reactions Three allergists on the StarLink panel questioned the FDA's choice of the ELISA allergy test. Dr. Sampson recommended immunoblotting. Drs. Metcalfe and Rothenberg suggested skin prick tests. According to Dr. Metcalfe, the skin test 'gets around a lot of the complications of ELISAs.'

In the ELISA test, the suspected allergen (i.e. allergy-causing protein) is exposed to blood from allergy sufferers. If antibodies in the blood bind to the allergen, that food probably caused the allergic reaction (food challenge tests are used for confirmation). Antibody and allergen are like lock and key. Even a slight change in the allergen (key) can prevent it from binding to the antibody (lock).

The suspected allergen in StarLink corn is the Cry9C protein. Surprisingly, the FDA did not use Cry9C extracted from StarLink corn in its allergy test. Instead, it used a bacterial surrogate protein grown in E. coli bacteria. The bacterial version of Cry9C differs in molecular weight and structure from StarLinkís Cry9C, which appears to have added sugar molecules (glycosylation) not present in the bacterial protein. These extra sugar molecules increase the likelihood that StarLink Cry9C is allergenic. In addition, antibodies to StarLink corn Cry9C may not recognize the bacterial surrogate used in testing, resulting in ìfalse negatives.î The FDA should have used StarLink-derived Cry9C in its tests.

Special Risks to Infants and Young Children Not Accounted For

According to the StarLink panel allergy experts, children are at greater risk of allergy to StarLink's Cry9C protein than adults. This is because children:

1) Are more prone to allergies in general than adults; 2) Are sensitive to smaller quantities of allergen (in some cases, even trace amounts); 3) Are particularly susceptible to allergy from novel proteins such as Cry9C; and
4) Often have diets richer in corn than adults.

Food-allergic infants and children are a special concern. They are often prescribed corn-rich diets (e.g. hypoallergenic infant formulas can contain over 50% corn) precisely because corn is rarely allergenic. Thus, the most allergy-sensitive population is also ingesting the most corn, and so potentially the most Cry9C.

Despite this increased risk, the government has failed to take the proper steps to test and protect children from possible allergic sensitization to Cry9C. 1) The EPA has failed to investigate the amount of Cry9C in infant foods, as recommended by the StarLink panel; 2) As far as we know, the FDA has tested only one child for allergy to Cry9C. If the FDA had alerted pediatricians to the possibility of allergic reactions to corn, more children might have been included in the FDAís testing program. A larger sample of children -- the population at highest risk -- is crucial to determine whether StarLinkís Cry9C can cause allergies.

Estimates of Exposure to Cry9C Called 'Speculation'

Aventis claims that the amount of Cry9C in food products is too low to cause allergies even if it is an allergen. Yet the StarLink panel called this exposure-based approach 'speculation' for a number of reasons, including: 1) Cry9C levels in food may be underestimated due to failure to detect Cry9C fragments and/or denatured protein, which may be allergenic; 2) Allergic sensitization and response can reportedly be triggered by billionths of a gram of allergen, especially in young children; 3) The exposure estimates do not take account of Cry9C contaminating non-StarLink corn through cross-pollination, a problem affecting at least 80 seed companies, as well as popcorn and sweet corn growers.

Comparison of two tests Aventis used to measure Cry9C reveals two-fold to nine-fold differences for various foods, raising serious questions about the accuracy of any Cry9C protein test, even with state-of-the-art science.

The Government Should Not Approve Any Level of StarLinkís Cry9C in Food

StarLink's developer (Aventis CropScience) has petitioned the EPA to approve low levels of Cry9C in food. Given the hundreds of uninvestigated allergy reports, the flaws in the FDA's allergy test, and the serious unanswered questions with respect to children, the government must not approve any level of Cry9C in the food supply. Such an approval would show a blatant disregard for public health to suit the interests of the powerful food and biotech industries.

Quotes from the StarLink Scientific Advisory Panel Report and Transcript

On the special risk of Cry9C to children

1. 'Children exposed to Cry9C may be more sensitive than adults.' (SAP Report No. 2000-06, 12/1/00, p. 14)

2. 'Allergic responses can also be triggered by trace proteins following sporadic exposure, especially in young children. food allergy can be encountered in exclusively breast-fed infants.' (SAP Report, p. 16)

3. 'In humans, a critical period is the first two years of life when the gastrointestinal immune system is relatively predisposed to allergic responses. Study of infant diets is therefore the highest priority.' (SAP Report, p. 14)

4. 'I haven't seen any definitive information about assessing what exactly is the level [of Cry9C], particularly in the first year of life, in baby foods that are containing corn products.' (Dr. Marc Rothenberg, SAP transcript, p. 439)

5. 'In some of the children we deal with, they're basically ingesting an amino acid formula plus corn in a variety of ways, pasta, corn chips, corn flakes, grits, whatever. So, these children who are at highest risk for developing allergy are really getting way over the levels that people are predicting for corn, and if this is a potential allergen, that would be of great concern to me.' (Dr. Hugh Sampson, speaking of the risk of Cry9C to food-allergic children; SAP Transcript, pp. 395)

On the need for outreach to the medical & allergy communities

1. 'The Panel felt that the medical community should be informed of the investigation into the allergenicity of Cry9C in corn products. In addition, monitoring reports from the medical community could supplement the cases currently under investigation and could provide additional support for proving or refuting the allergenicity of Cry9C.' (SAP Report, p. 26)"