Reply

Abstract

The letter of Dr Luca Bucchini merits a response because it raises some useful points and allows us to expand on the food safety focus of our recent article.1Taylor SL Hefle SL Will genetically modified foods be allergenic?.J Allergy Clin Immunol. 2001; 107: 765-771Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar Indeed, we readily admit that our article focused primarily on the potential allergenicity of genetically modified foods when ingested. Dr Bucchini indicates that we did not sufficiently emphasize the potential adverse impacts of the release of a genetically modified crop that was subsequently documented to be allergenic. Dr Bucchini appropriately indicates that such an event would have tremendous adverse economic consequences and would be difficult to rectify because of the existing situation with respect to crop handling and distribution practices. We certainly agree that the release of an unsuspected allergenic crop into the marketplace would be quite disruptive in terms of both public health and the agricultural economy. However, we would argue that these risks mandate that a careful assessment of the potential allergenicity of each new genetically modified food be conducted before commercial release of that product. Multiple measures of the potential allergenicity of the genetically modified food must be included to improve the reliability of such assessments, as indicated in the decision-tree strategy advocated in our article. We readily agree that there is no single test that could be conducted with the novel proteins contained in genetically modified foods that would be fully predictive of their potential allergenicity except in cases in which the novel protein might be acquired from a known allergenic source. We wish to emphasize that the ability to predict the potential allergenicity of novel proteins derived from sources with no history of allergenicity is improving as scientists identify and characterize more allergens. In fact, during the interval between the submission of our article and its publication, the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) released a new decision-tree approach developed by worldwide experts (Fig 1) that is more rigorous than the approach advocated in our article. Although sufficient space is not available for a complete discussion of this approach here, the full FAO/WHO report can be accessed at www.who.int/fsf/Gmfood/ . We hope that Dr Bucchini will agree that this more rigorous assessment approach will improve scientific confidence in allergenicity assessments for genetically modified foods. As our scientific understanding improves, we trust that organizations such as FAO and WHO will continue to perfect that allergenicity assessment strategy. Dr Bucchini cites the experience with StarLink corn as an example of the potential disruptions that can be caused by the release of genetically modified crops when uncertainty remains regarding their allergenic potential. As noted in our article, StarLink corn and the novel cry9c protein that it contains failed the decision-tree approach for allergenicity assessment that was advocated in our article. As a consequence, StarLink was never approved for human consumption. Its commercial release as a crop intended exclusively for animal feed can properly be characterized as a failure in risk management that did indeed have tremendous economic repercussions. However, though the potential allergenicity of the novel cry9c protein in StarLink is officially unresolved from a regulatory perspective, we stand by the statement in our article that StarLink corn is probably not allergenic. According to data released just recently by the Centers for Disease Control and Prevention (CDC), an examination of blood serum from individuals who might have suffered adverse reactions to StarLink corn failed to find any cry9c-specific IgE antibodies. The CDC appropriately concluded that no evidence exists for allergic reactions to StarLink corn and its novel cry9c protein. The full report on the CDC investigation of reactions to StarLink corn can be found at www.cdc.gov/nceh/ . Dr Bucchini notes that we did not consider potential allergenic risks posed by pollen exposures or dermal exposures associated with genetically modified plants. Indeed, the decision-tree approaches focus on ingestion exposure. However, when sequence homology comparisons are made, these would include comparisons to all known allergens, including pollen and other plant allergens. We would argue that more is known about the structures of pollen allergens than the structures of food allergens, and the likelihood of identifying a prospective pollen allergen in a genetically modified food plant is reasonably good as a result. The targeted serum screening advocated in the more recent FAO/WHO decision-tree approach also addresses this concern. Certainly, the risks posed by the pollens of genetically modified plants should not be ignored in the safety assessment process. 1/8/118291