The US Food and Drug Administration (FDA) is proposing to expand a controversial loophole to allow some of the world’s most toxic chemicals to be added directly to food without a safety review.

The “threshold of regulation” (TOR) exemption currently allows dangerous compounds to be used without review in food contact materials, such as packaging or processing equipment, if they are not carcinogenic, and are added at levels below 0.5 parts per billion (ppb).

But campaigners say many chemicals, especially hormone disruptors linked to brain damage and reproductive harm in children, are considered dangerous at levels far below 0.5ppb. Even in its limited form, the loophole has already raised alarm. One TOR exemption that allows the rocket fuel chemical perchlorate to be used in grain bags dramatically increased the amount of the compound found in kids’ cereal, which advocates say could cause brain damage.

The new proposed TOR expansion would allow companies to use the chemicals as an ingredient added directly to food, as flavorings, preservatives, emulsifiers, processing aids, enzymes, stabilizers and binders, and for myriad other uses, in ultra-processing.