The U.S. Food and Drug Administration (FDA) has published the results of targeted testing of clams for per- and polyfluoroalkyl substances (PFAS), which showed a broad range of detectable levels of at least one type of PFAS in all samples.

Perfluorooctanoic acid (PFOA)—one of the most common PFAS types, which the World Health Organization (WHO) has deemed a carcinogen—was found in all samples.  

FDA’s targeted testing of clams was conducted as a follow-up to its 2022 PFAS in seafood survey, in which the agency tested the ten most popular types of seafood in the U.S. for the presence of “forever chemicals.” The 2022 survey revealed high levels of PFOA in samples of canned clams from China intended for human consumption, and FDA determined that the estimated exposure to PFOA from the samples was likely a health concern. After the survey, FDA continued sampling processed clams that were intended for human consumption as they entered the U.S. from the two processors associated with the highest levels of PFOA detected during the 2022 seafood survey.

Additionally, between October 2022 and September 2024, FDA collected and analyzed 12 samples of processed clams with China as the country of origin. All 12 samples had detectable levels of at least one type of PFAS, and PFOA was detected in all samples. A total of three shipments were refused entry into the U.S.

However, in 2023, FDA also conducted a small survey of nine domestically acquired clam samples, six of which specifically identified the U.S. as their country of origin, collected at retail establishments in the Washington, D.C. area. All but one of the nine samples had PFOA concentrations under the method detection limit, which is the minimum concentration of a substance that can be measured and reported with 99 percent confidence that the analyte concentration is greater than zero.

FDA states it is actively engaging with imported and domestic clam firms to better understand potential sources of PFAS contamination and ways in which PFOA concentrations may be reduced.