Aqueous Film-Forming Foam (AFFF) has been widely used as an effective fire suppressant, especially for fires involving flammable liquids like jet fuel. Its unique properties allowed it to quickly extinguish challenging blazes, making it a standard in military, aviation, and industrial firefighting for decades. However, concerns have emerged regarding the chemical composition of AFFF and its potential impact on human health. This article explores the scientific evidence linking AFFF to cancer and other health issues, examining the chemicals, exposure pathways, and associated health risks.
The Chemicals in AFFF
AFFF contains a class of synthetic chemicals known as Per- and Polyfluoroalkyl Substances (PFAS). These chemicals are often referred to as “forever chemicals” because their strong carbon-fluorine bonds make them highly resistant to breaking down in the environment and the human body. PFAS have been used in various products since the 1940s due to their ability to repel water, oil, and stains. In AFFF, PFAS create a film that effectively smothers liquid-based fires by cutting off oxygen.
The two most extensively studied PFAS compounds are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). While PFOA was not an intended ingredient in AFFF, it could be present as a byproduct of manufacturing, and PFOS was a common component in older AFFF formulations. Although these specific compounds are being phased out in the U.S., newer PFAS chemicals with similar properties may replace them in AFFF formulations. The persistence of PFAS allows them to accumulate in people, animals, and the environment, posing long-term concerns.
How Exposure Occurs
Individuals can be exposed to AFFF and its PFAS components through several pathways, including direct contact, inhalation, and ingestion. Occupational exposure is a significant concern for firefighters, military personnel, and airport workers who regularly handle AFFF during training exercises, emergency responses, and equipment testing. Firefighters can also absorb PFAS through their skin, particularly from protective clothing treated with fluoropolymers.
Environmental contamination poses risks to broader communities. AFFF releases from training sites, industrial facilities, and military bases can leach PFAS into groundwater and drinking water sources. People living near these sites may consume contaminated drinking water or food, leading to indirect exposure. PFAS are highly mobile in water, allowing them to travel long distances from their origin and contaminate water supplies.
Health Concerns Linked to AFFF Chemicals
Exposure to PFAS chemicals in AFFF has been linked to a range of adverse health outcomes. These substances can accumulate in the body, affecting various organ systems and potentially disrupting normal cellular functions. Scientific research suggests that certain PFAS may lead to increased risk of specific cancers.
Cancers associated with PFAS exposure include kidney cancer, testicular cancer, prostate cancer, breast cancer, and thyroid cancer. Some studies also suggest links to ovarian and uterine cancers, liver cancer, pancreatic cancer, bladder cancer, and certain blood cancers like non-Hodgkin lymphoma and leukemia.
Beyond cancer, PFAS exposure has been linked to other serious health issues. These include reproductive effects such as decreased fertility and increased high blood pressure in pregnant women. Developmental effects in children, such as low birth weight and altered puberty, have also been observed. Other non-cancer health concerns include:
Ulcerative colitis
Thyroid disease
Liver damage
Increased cholesterol levels
Reduced immune system function
Decreased vaccine response
The Scientific Evidence
The scientific understanding of the links between PFAS and adverse health effects, particularly cancer, primarily comes from epidemiological studies and toxicological research. Epidemiological studies investigate patterns of disease in human populations with varying exposure levels. Toxicological studies, often conducted in animals, explore the mechanisms by which chemicals might cause harm.
A significant body of evidence stems from the C8 Science Panel, formed as part of a class-action lawsuit against DuPont. This panel conducted an extensive health study involving approximately 69,000 people exposed to PFOA (also known as C8) through contaminated drinking water near a manufacturing plant. The C8 Science Panel concluded that a “probable link” existed between PFOA exposure and several health conditions, including kidney and testicular cancer.
Regulatory bodies and research organizations worldwide have also assessed the evidence. The International Agency for Research on Cancer (IARC) classified PFOA as “carcinogenic to humans” (Group 1) based on sufficient evidence in animals and strong mechanistic evidence in humans. IARC also classified PFOS as “possibly carcinogenic to humans” (Group 2B). The U.S. Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) acknowledge the associations between PFAS exposure and various health effects, including increased cancer risk.
While directly proving causation can be complex due to the multitude of factors influencing human health, the growing scientific consensus points to strong associations. This ongoing research continues to refine the understanding of how AFFF chemicals affect human health.