03 · Contamination pathway
From firefighting foam to your bloodstream.
Click any stage of the pathway below. Each node shows the chemistry governing PFAS movement, the impact at that stage, and a documented real-world example.
Source: AFFF firefighting foam
Aqueous Film Forming Foams (AFFF) used at military bases and airports historically contained 1–5% fluorosurfactants — chiefly PFOS (C8F17SO3⁻) and PFOA (C7F15COOH). Repeated training discharges deposit kilograms of PFAS per event onto unlined soil.
The C–F bond (~485 kJ·mol⁻¹) resists hydrolysis, photolysis, and microbial attack. Released PFAS persist effectively indefinitely and migrate downward with rainfall.
U.S. DoD has identified ≥ 700 installations with confirmed AFFF-derived PFAS contamination (2023 inventory).
Why this pathway?
Of the many ways PFAS reach humans (food packaging, indoor dust, industrial air emissions), contaminated drinking water from AFFF release sites is the route with the largest documented dose-response evidence — the C8 Health Project alone sampled nearly 70 000 people. It also demonstrates every key process: industrial release, soil sorption, groundwater transport, aquatic bioaccumulation, trophic transfer, and human ingestion.