Aqueous Film-Forming Foam (AFFF) is a specialized fire suppressant developed in the mid-1960s, primarily by the U.S. Navy. It was designed to combat high-intensity fires fueled by flammable liquids like jet fuel and oil. AFFF was quickly adopted as the standard for fire suppression at military installations and civilian airports because it rapidly smothers flames and prevents re-ignition. The concern regarding AFFF exposure stems from its core components: Per- and Polyfluoroalkyl Substances (PFAS). These synthetic chemicals are responsible for the foam’s effectiveness but pose significant risks when released into the environment and the human body.
Understanding PFAS: The Persistent Chemicals in AFFF
Per- and Polyfluoroalkyl Substances (PFAS) are the chemicals that make AFFF effective. This large group of man-made chemicals has been used since the 1950s in various industrial and consumer products. PFAS compounds are characterized by a unique structure featuring a chain of carbon atoms bonded to fluorine atoms. This carbon-fluorine bond is one of the strongest in organic chemistry, giving PFAS exceptional resistance to heat, water, and oil.
This stability causes PFAS to be frequently referred to as “forever chemicals,” because they do not break down naturally in the environment or the human body. They exhibit high environmental persistence and mobility, easily dissolving in water and contaminating groundwater sources. Furthermore, PFAS bioaccumulate, meaning they build up in the tissues and bloodstream of living organisms, including humans, with repeated exposure.
The two most widely studied compounds historically found in AFFF formulations are Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA). While manufacturers have phased out these long-chain PFAS, newer AFFF products often contain structurally similar short-chain PFAS. These alternatives are also highly mobile and persistent, meaning the risk of contamination from foam use continues.
Common Sources and Pathways of AFFF Exposure
Exposure to PFAS released from AFFF is linked to its historical use in high-risk fire scenarios and training exercises. The primary geographical sources of contamination are sites where large volumes of foam were regularly discharged, such as military installations and civilian airports. The U.S. military was the largest consumer of AFFF, utilizing it extensively at bases with aviation operations for emergency response and training drills. Civilian airports also relied heavily on AFFF to comply with Federal Aviation Administration (FAA) safety regulations, leading to significant contamination from repeated use.
There are three main pathways through which individuals come into contact with these contaminants. The most widespread pathway is through contaminated drinking water, which occurs when the highly soluble PFAS leach from discharge sites into groundwater and surface water. This affects personnel on a facility and surrounding residential communities.
Another pathway is direct occupational exposure, affecting firefighters and military personnel who routinely handled or were sprayed with the foam during training and emergency operations. This involves dermal contact with the foam concentrate or solution, and inhalation of airborne particles and fumes after discharge. Secondary exposure also affects ground crew and maintenance workers who clean up spills or maintain contaminated equipment. The third pathway involves the ingestion of contaminated media, such as consuming produce grown in PFAS-contaminated soil or fish caught from contaminated water sources.
Health Outcomes Associated with PFAS Exposure
The long-term health consequences of chronic PFAS exposure are a major concern because these chemicals accumulate in the body. Scientific studies have identified several adverse health effects linked to elevated levels of PFAS in the bloodstream. These outcomes often depend on the duration and concentration of exposure.
PFAS are known to interfere with the endocrine system, leading to hormonal disruptions and an increased risk of thyroid disease. They have also been associated with metabolic disorders, including elevated cholesterol levels. The immune system can be affected, with research suggesting a weakened immune response and reduced effectiveness of vaccines.
Chronic exposure has been linked to an increased likelihood of developing certain cancers. The most consistently reported cancers are kidney cancer and testicular cancer. Studies also indicate links to other cancers, including prostate, bladder, and liver cancer. In pregnant individuals, PFAS exposure has been associated with reproductive issues, such as fertility problems and an increased risk of pre-eclampsia. Exposure can also affect fetal and child development, including low infant birth weight.