StarLink™ corn (Aventis Crop Science USA LP) contains the protein Cry9c, genetically modified from the Bacillus thuringiensis subspecies tolworthi bacteria. This protein has pesticidal properties and was genetically inserted into StarLink™ corn to protect the crop against several insects, including the European corn borer, the cornstalk borer, and the corn earworm. In May 1998, the U.S. Environmental Protection Agency (EPA) granted a limited license for the production of StarLink™ corn. The license proscribed that this corn variety was to be grown only for animal feed, industrial nonfood uses, and seed increase. EPA did not license StarLink™ corn for use in food intended for human consumption because the Cry9c protein shared several molecular properties with proteins that are known food allergens. Despite the EPA ruling, Cry9c-DNA was detected in taco shells in September 2000. This discovery caused several food distributors to recall implicated product lines. Following the media coverage of the food product recalls, FDA began receiving reports of adverse health events from consumers who had eaten food products containing corn. In addition, the U.S. Department of Agriculture (USDA) pointed out that all corn, including the StarLink™ corn variety, is, in common practice extensively comingled after harvest. Ultimately, it was not known how much of the genetically engineered corn had entered the human food chain.
On October 25, 2000, FDA invited CDC to help review and investigate related adverse event reports (AERs) submitted to FDA. Further discussions were held between representatives of CDC’s National Center for Environmental Health (NCEH), FDA, EPA, and USDA. On November 16, 2000, CDC assigned EPI-AID #2001-13 to the Health Studies Branch, Division of Environmental Hazards and Health Effects, NCEH, CDC, to conduct the initial review and investigation.