What specific firefighting foam caused historically high occupational PFAS exposure for first responders?

Aqueous Film-Forming Foam (AFFF)

Occupational exposure to very high concentrations of PFAS historically occurred among certain professions, most notably firefighters and military personnel. The primary vector for this elevated exposure risk was the routine use of Aqueous Film-Forming Foam, commonly abbreviated as AFFF. This foam formulation was essential for effectively and rapidly extinguishing fires involving flammable liquids, especially in large-scale settings like military bases and airports. Because AFFF contained high concentrations of PFAS chemicals, individuals handling or working near this foam experienced significant uptake of these substances through both dermal absorption and inhalation, resulting in acute and chronic exposure levels far exceeding those typically seen in general consumer settings.