WASHINGTON - Biotech corn that spawned nationwide food recalls last fall didn't cause the allergic reactions that people reported after finding out about the grain, the government said Wednesday.

The federal Centers for Disease Control and Prevention (news - web sites) said its investigation of the complaints ``did not find any evidence that hypersensitivity'' to a special protein in StarLink corn caused the reactions.

Blood samples were taken from 17 people and tested for sensitivity to the protein, known as Cry9C.

StarLink corn was never approved for human consumption because of questions about whether it was an allergen. The Cry9C protein breaks down slowly in the digestive system, an indication that it might induce allergic reactions. However, scientists say people would have to be exposed to the protein repeatedly to become sensitive to it.

Critics of biotechnology say the CDC investigation was too limited to conclude that the corn is safe. ``This is a small piece of evidence,'' said Rebecca Goldburg, senior scientist with Environment Defense, an advocacy group. ``It's far from being definitive.''

StarLink is one of several types of corn that have been genetically engineered to produce its own pesticide.

StarLink was withdrawn from the market last year but not before the grain was found contaminating a significant portion of the nation's corn supply.

Discovery (news - web sites) of the corn in taco shells last fall led to nationwide recalls of corn products, and more recalls may be necessary unless the Environmental Protection Agency (news - web sites) agrees to allow a minimal amount of the corn in food, according to the corn's developer Aventis CropScience.

Aventis wants the EPA to set a maximum level for the biotech grain of 20 parts per billion - the equivalent of one StarLink kernel in every 800 kernels of corn. The EPA is expected to consider the CDC report in making its decision.

After the CDC began investigating complaints about StarLink, the Food and Drug Administration (news - web sites) developed a blood test that could tell whether someone was allergic to the Cry9C protein.

The 17 people who gave blood samples to CDC were among 24 people interviewed by investigators after reporting complaints.

Keith Finger, a Florida optometrist who was included in the CDC study, said he suffered a severe allergy attack last September shortly before the first recall of a StarLink-tainted product, Taco Bell-brand taco shells.

Finger said he had a meal containing corn ingredients shortly before the attack, which included severe stomach cramps and swelling of his throat. He has since eaten the same products, which included a tortilla made with corn starch, without a reaction, he said.

CDC's findings should give EPA ``the final piece of information'' it needs to approve the Aventis request, said Val Giddings, a spokesman for the Biotechnology Industry Organization.

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