Council For Agricultural Science And Technology

Comments Of Steve L. Taylor, Ph.D. On Starlink Bt Corn

Steve Taylor, Ph.D. participates in the CAST Communicators Program. As with all comments from CAST Communicators, the comments are his own and do not necessarily reflect the opinions of CAST or its member societies. Professor and Head Department of Food Science and Technology University of Nebraska - Lincoln Presented to the United States Environmental Protection Agency, FIFRA Scientific Advisory Panel on Bt Plant Pesticides: Risk and Benefit Assessments

I regret that a prior professional commitment in Australia keeps me from attending the science advisory panel in person.1 As past Chair of an international panel of scientists formed to develop a model approach to assessing the safety of genetically modified foods, I am concerned that the recent incidents with taco shells and unapproved corn may not have been fully understood by the public or the food industry.

First, I must say that I was dismayed that a product was allowed on the market for animal feed use when it had not been approved for human food use. I believe that was a mistake, however I do not believe there has been any risk to the public.

The corn in question, StarLink Bt corn developed by Aventis, is the only product among about 40 genetically modified crops on the market that has not been approved for use in human foods. All biotech crops on the market today have been assessed by the Food and Drug Administration, the Environmental Protection Agency and the Department of Agriculture. The protocols followed by those agencies ensure that any product approved for food use has passed all tests for substantial equivalence and for the safety of the newly introduced gene(s) and proteins and should therefore be considered as safe as its conventional counterpart.

StarLink, was not approved for food use because the product did not pass all screens for allergenicity. The Bt protein in StarLink, Cry9C, does not resemble known allergens, so in fact it may not be an allergen. However, Cry9C was not immediately broken down in digestion tests. Because most food allergens also are not readily digested, EPA wanted more data before concluding that the protein would not become an allergen. On this basis, the agency was correct in awaiting additional information and approval for food use is pending. Other Bt products on the market contain a Cry1 protein, which is digested in a matter of seconds and has passed all of the other screens for allergenicity. Furthermore, Cry1 proteins have been present in foods via Bt sprays used by organic and other farmers for many years.

But was the public at risk because of this incident? I believe it was not.

In order for people to become allergic to a protein they must be exposed to it multiple times over an extended period until they become sensitized. The protein must also be present as a relatively high percentage of total protein content. Most allergenic proteins are present at levels of 1 to 40 percent. Aventis indicates that the Cry9C protein is present in corn grain at 0.013 percent, but any taco shells would contain far less due to the presence of other varieties of corn and the use of other ingredients.

It is highly unlikely that Cry9C protein would be present in any corn products at a level of concern. It is important to understand that only a very small amount of StarLink corn was planted, about 350,000 acres among the nearly 80 million corn acres in the United States (0.3 to 0.4 of a percent). That small amount could conceivably be produced by only 100 large farms. Because of the feed-only restriction, nearly all would have been properly channeled to feed operations, but even if the production from some farms was improperly channeled, the amount entering the food supply would be of a relatively low percentage when mingling with other grain is taken into consideration.

This clearly would not produce protein levels of any health concern. It is unfortunate that this incident has sent a negative message to consumers because I believe that U.S. regulatory procedures ensure that any genetically modified crop approved for food use is as safe as its conventional counterpart. StarLink is the only product not approved for food use, and we can almost certainly expect that it will be the last.

Steve L. Taylor, PhD Professor and Head Department of Food Science and Technology University of Nebraska - Lincoln

Dr Taylor's comments were presented to the SAP on October 20, 2000 by Jason Hlywka, PhD. Dr. Hlywka completed two years of post-doctoral training in a research position with Dr. Taylor at the Food Allergy Research and Resource Program (FARRP) at the University of Nebraska. Dr. Hlywka will be available to respond to questions.

If you have questions about the CAST Communicators Program, please feel free to contact Cindy Richard at 202-408-5383 (crichard@cast-science.org) or visit the CAST website at www.cast-science.org.

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