From Stable to Table: Tracing the "Forever Chemical" Vector Through the Food Animal Supply Chain

Per- and polyfluoroalkyl substances (PFAS) represent a formidable class of persistent synthetic chemicals whose contamination of the global food supply, particularly through animal products, constitutes a major and direct route of human exposure. This review synthesizes the current scientific understanding of PFAS entry into food animal production systems including livestock, poultry, and aquaculture via contaminated feed, water, and soil. We detail the subsequent toxicokinetics in animals, which lead to pronounced tissue-specific bioaccumulation. Two distinct and non-interchangeable rankings are therefore applied throughout this review. On a concentration basis (ng g^-1 wet weight in the edible matrix), liver and kidney consistently exceed muscle by approximately one to two orders of magnitude within the same animal, while among marketed commodities the descending order is generally offal > certain seafood > eggs > milk and dairy ≈ muscle meat. On a population dietary-intake basis (ng kg^-1 body weight week^-1), the ranking reverses for several commodities because intake is the product of concentration and consumption: seafood, muscle meat, eggs and dairy dominate total intake in most national diets, whereas offal contributes episodic high-dose exposure in a minority of consumers. The analysis confirms that animal-derived foods are a dominant contributor to dietary PFAS intake. Epidemiological studies report consistent positive associations between the consumption of these commodities and human serum concentrations; such associations characterize internal exposure and source attribution, and are distinguished here from formal risk characterization, which requires comparison of estimated intakes with health-based guidance values such as the EFSA tolerable weekly intake of 4.4 ng kg^-1 body weight week^-1 for the sum of PFOA, PFNA, PFHxS and PFOS. We critically examine the fragmented and lagging regulatory landscape governing PFAS in food, highlighting significant data gaps concerning novel replacement compounds and mixture effects. The review concludes that mitigating this public health threat requires an integrated "Farm-to-Fork" strategy, encompassing source control in agriculture, proactive food safety monitoring, and the development of harmonized international standards. Addressing PFAS contamination in food animals is therefore not merely an environmental issue but an urgent imperative for safeguarding food security and public health.