In 1961, a DuPont toxicologist warned colleagues that exposure to their company’s increasingly popular Teflon chemicals enlarged the livers of rats and rabbits. Studies over the following decades found no safe level of exposure in animals and determined that humans, too, got sick when exposed to the chemicals — which were also seen to build up in the body and resist breakdown in the environment.
Nonstick, it turned out, tends to stick around.
By the end of 2015, some of these most notorious polyfluoroalkyl and perfluoroalkyl substances, or PFASs, will be fully phased out of use in the U.S. But emerging in their place, warn environmental health experts, are another group of PFASs that share many of the same concerning characteristics.