How PFAS Moves Through Ecosystems
PFAS compounds released into water and soil environments are taken up by organisms at the base of food chains — aquatic invertebrates, plants, and microorganisms — and accumulate at increasing concentrations as they move to higher trophic levels through the process of biomagnification. Unlike many persistent organic pollutants, PFAS compounds bioaccumulate primarily in blood and protein-rich tissues rather than fat, making traditional lipid-based bioaccumulation models less predictive of PFAS behavior.
Fish and Seafood Consumption
Fish consumption is a significant PFAS exposure pathway, particularly for long-chain perfluorocarboxylic acids including PFOS, PFNA, and PFCA compounds. Several states have issued fish consumption advisories for water bodies near PFAS contamination sources. Freshwater fish from contaminated lakes and rivers often show PFAS levels that exceed health-based guidelines when consumed at typical rates. Ocean fish generally show lower PFAS levels than freshwater species near contaminated sites, though deep-sea fish can accumulate PFAS through oceanographic transport pathways.
Produce and Livestock
Irrigating crops with PFAS-contaminated water introduces PFAS into the food supply through plant uptake, creating exposure pathways independent of drinking water. Livestock consuming PFAS-contaminated water or feed accumulate PFAS in tissues and dairy products. Studies of farms near PFAS contamination sites have found elevated PFAS in produce, meat, and dairy products, prompting USDA and FDA food safety investigations and, in some cases, agricultural product recalls.
Total Dietary Exposure Assessment
The EPA and FDA are developing integrated dietary PFAS exposure assessments that account for food chain bioaccumulation alongside drinking water exposure. For populations consuming locally caught fish from contaminated areas, dietary PFAS exposure can substantially exceed drinking water exposure even after drinking water treatment. Comprehensive PFAS exposure reduction for affected communities requires attention to both water and food supply pathways.