Skip Navigation

June 2001

June 13, 2001

CDC Found No Evidence of Hypersensitivity
to the Cry9C Protein in StarLinkTM Corn

Source: Center for Disease Control and Prevention

CDC involvement in investigating adverse health effects associated with eating corn products potentially contaminated with the Cry9C Protein in StarLinkTM corn

In May 1998, the U.S. Environmental Protection Agency (EPA) granted a limited license for the production of StarLinkTM corn containing the protein Cry9c. This protein has pesticidal properties and was inserted into StarLinkTM corn to protect the crop against several insects. The EPA did not license StarLinkTM for use in food intended for human consumption because the Cry9c protein shared several molecular properties with proteins that are known food allergens.

In response to a request from EPA in October of 2000 the U.S. Food and Drug Administration (FDA) requested assistance from the Centers for Disease Control and Prevention (CDC) in investigating possible adverse health effects among people who had reported to FDA that they may have had an allergic reaction to eating corn products contaminated with the Cry9c protein in StarLinkTM corn.

CDC’s investigation did not find any evidence that hypersensitivity to the Cry9c protein was responsible for the self-reported allergic responses that people experienced last fall.

Our field investigation included the following:

  1. Reviewing the adverse event reports (AERs) that FDA/Center for Food Safety and Applied Nutrition received from consumers in the United States or its territories who reported adverse health events between July 1, 2000, and November 30, 2000, and involving a product suspected of containing corn meal contaminated with StarLinkTM corn.
  2. Contacting persons who gave permission to the FDA for CDC to speak with them. CDC field investigators asked basic questions about food consumption and signs and symptoms that each person recalled experiencing when they consumed corn products. CDC obtained medical records and collected blood specimens from each person for later laboratory tests.
An FDA laboratory developed a laboratory method to detect the type of antibody (IgE) that would indicate hypersensitivity to the Cry9c protein that was inserted into StarLinkTM corn.

CDC asked FDA to evaluate the case report samples as well as other reference samples using this developmental method. To avoid bias in the laboratory analysis, all samples were provided to FDA with just a simple code number.

FDA returned the data to CDC and CDC analyzed it to compare case values with control values.

Although the study participants may have experienced allergic reactions, based upon the results of this study alone, we cannot conclude that a reported illness was a Cry9c allergic reaction.

An independent laboratory analyzed the same set of coded samples that CDC sent to FDA and confirmed the results.

CDC reviewed this data and issued individual reports to the study participants. CDC has also sent a report of the investigation and study results to FDA, and FDA will provide this information to EPA. EPA will consider the results of the CDC study and other data as it makes recommendations about the use of Cry9c.

CDC is continuing to work with FDA to evaluate the AER system for identifying potential health outcomes.

To access the full report, log onto