As of April 1, the FDA has not yet released the results of follow-up studies on approximately 20 people who reported allergic reactions after eating food containing corn products last summer or fall. The tests are to assess whether the reaction was triggered by the presence of the Cry9c protein that make StarLink varieties corn resist certain insects. The EPA approved the Cry9c protein for cattle feed but not for human food because of concerns that the protein might trigger allergic reactions.

On March 7 the EPA announced that it will no longer issue such "split registration" for so-called "plant-incorporated pesticides" such as Cry9c. Cry9c was the only such split registration EPA issued, approving the use of corn varieties expressing the Cry9c for feed but not for food. However, this leaves open the question of how the FDA and USDA will regulate crops engineered to produce medicines or industrial feedstocks such as enzymes or biodegradeable plastics. EPA regulates Cry9c because the agency considers the protein a pesticide.