Certain kinds of greaseproofing "forever" chemicals called per- and poly-fluoroalkyl substances, or PFAS, will no longer be used in food packaging in the U.S., the U.S. Food and Drug Administration announced Wednesday.Video above: FDA approves first medication to reduce allergic reactions for people with food allergiesThe FDA's food studies have shown that food packaging materials like fast-food wrappers, microwave popcorn bags and take-out pizza boxes were a major source of dietary exposure to certain types of PFAS, hormone-disrupting chemicals that may persist in the body and the environment.PFAS have been linked to a variety of health effects including changes in immune and liver function, obesity, diabetes, certain cancers and lower birth weights.While health and environmental advocates cheered the new announcement, they noted that companies were already facing pressure from state bans to get PFAS out of consumer products, including food packaging."I am enthusiastically supportive of getting PFAS out of food packaging," said Dr. Leonardo Trasande, a professor of pediatrics and population health at NYU Langone Health in New York City, who has studied the health impacts of PFAS. "We are talking about a decent chunk of ongoing exposure."Twelve states have moved to ban or phase out PFAS in food packaging, said Melanie Benesh, vice president of government affairs for the nonprofit Environmental Working Group."This is really the culmination of state action to drive PFAS out of the marketplace and, particularly, to drive PFAS out of food packaging, where alternatives have existed for a long time," Benesh said.In 2020, the FDA announced that chemical manufacturers would voluntarily phase out certain kinds of PFAS for use in food packaging within three years, after a scientific review concluded that these chemicals could linger in the body longer than anticipated."This 'win' for public health is the result of FDA research and leadership, combined with cooperation from industry," noted Jim Jones, the FDA's deputy commissioner for human foods, in a news release on the milestone at the time.Wednesday's announcement doesn't mean the wrapper of your next fast-food burger won't contain PFAS, however. The FDA estimates that it may take another 18 months after this phase-out to exhaust stocks of products containing these food contact substances.Chemicals called long-chain PFAS stopped being sold in the U.S. due to safety concerns in 2011. Manufacturers then substituted short-chain PFAS, which have fewer carbons in their structure and weren't thought to be as hazardous as long-chain PFAS, in their products to replace them.Short-chain PFAS weren't thought to build up in living organisms the way long-chain PFAS do, but research has shown that they may be metabolized into forms that linger in tissue.