PFAS (forever chemicals)

Per- and polyfluoroalkyl substances (PFAS) are a class of more than 10,000 synthetic chemicals characterised by extremely stable carbon-fluorine bonds, resulting in environmental persistence and, for long-chain variants such as PFOA and PFOS, serum half-lives in humans of several years. Exposure routes include contaminated drinking water, food packaging, non-stick cookware and occupational contact; PFAS have been detected in blood and tissue globally, including in remote Arctic populations. Epidemiological evidence links PFAS exposure to suppressed antibody responses to vaccines, dyslipidaemia, thyroid hormone disruption, reduced birthweight and increased risk of kidney and testicular cancers, with mechanistic pathways involving PPAR-alpha activation and nuclear receptor interference. In 2024 the US EPA set enforceable maximum contaminant levels for PFOA and PFOS at 4 parts per trillion in drinking water; the EU is pursuing a restriction under REACH covering entire PFAS groups.