Testimony before the U.S. Congress revealed that the dangerous ingredient was approved for human use, meaning it could have made its way into the human food supply, CBS News reported Friday.
Sources told CBS at least one batch of wheat gluten suspected to be tainted was tracked into the food supply, leading to the quarantine of some products. However, tests of the food showed no problems.
The Centers For Disease Control and Prevention has been warned to be on the lookout for hospital patients with renal or kidney failure.
"We didn't know at the time whether or not wheat gluten had made it into the human food supply," said Dr. Stephen Sundlof, director of the FDA's Center for Veterinary Medicine. "We asked CDC to put a special emphasis on looking at increased incidents of renal failure in people."
The FDA told Congress there's "no evidence" that any of the bad gluten made its way into human food.