More than 35% of additives deemed harmless between 1997 and 2012 were evaluated by employees of food manufacturers or by consultants the companies selected, researchers report today in JAMA Internal Medicine, an adjunct of the Journal of the American Medical Association.

“It raises a number of questions,” says chemical engineer Thomas Neltner, the study’s lead author and the director of the food additives project at the Pew Charitable Trusts in Washington, DC. He and colleagues say their work shows a need for better oversight of additives by the U.S. Food and Drug Administration (FDA), which currently allows manufacturers to decide for themselves whether their products are safe to eat.

The team examined safety notices voluntarily submitted to the FDA by food manufacturers between 1997 and 2012. The filings informed the agency that a manufacturer considered an additive to be ‘generally recognized as safe’ (GRAS) and would use the substance in foods. Such decisions are supposed to be based on safety studies in which lab rats are fed the additive, and the FDA can question the decision.

But, Neltner explains, manufacturers are not required to notify the FDA when they make a GRAS decision or start using a new additive. His team estimates that manufacturers have not informed the FDA about 1,000 additives that are currently used in foods.

Michael Hansen, a senior scientist with the Consumers Union based in Yonkers, NY, says that the fact that food manufacturers are allowed to self-approve additives without informing the FDA is unacceptable. “That should not be allowed — period.”

At a workshop today in Washington hosted by Pew and Nature, regulators, scientists and representatives of food manufacturers discussed the new findings, current regulations and draft guidelines for evaluating additive safety that the Pew plans to submit to the FDA in coming weeks. Central among those recommendations: that individuals with financial conflicts of interest should be disqualified from making decisions about additives.

Manufacturers say that is in their companies’ best interests to ensure additive safety, because the firms would be held accountable if their products sickened consumers. But Neltner and other researchers say that no matter how careful or well-intentioned a company may be, someone with a financial interest in the success of a product can subtly influence that company’s decisions.

Jill Hartzler Warner, acting associate commissioner of special medical programs at the FDA, who gave a presentation on conflicts of interest at the workshop, said that the agency would review the recommendations.