Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals known for their widespread presence and potential for harm. Often called “forever chemicals,” PFAS do not naturally break down in the environment, posing a public health concern. Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are two prominent members of this group. Their persistence and accumulation in living organisms highlight the need to understand their properties.
Understanding PFOS and PFOA
PFOS and PFOA are human-made compounds with a unique chemical structure: a chain of carbon atoms strongly bonded to fluorine atoms. This carbon-fluorine bond is exceptionally strong, making them highly stable and resistant to degradation from heat, water, oil, and environmental processes.
Their robust nature made PFOS and PFOA desirable for industrial and consumer applications for decades. They were historically used to impart water, grease, and stain-resistant properties to many products. This chemical resilience allows them to persist in the environment for exceptionally long periods.
Common Sources and Environmental Spread
PFOS and PFOA have entered the environment through various pathways, leading to widespread distribution. Industrial manufacturing facilities that produced or used PFAS chemicals were significant sources, releasing them into air, water, and soil.
Another major source is aqueous film-forming foams (AFFF) used in firefighting. Consumer products also contributed to their environmental presence, including:
Non-stick cookware
Stain-resistant carpets and fabrics
Water-repellent clothing
Food packaging
The disposal of these PFAS-containing products in landfills can lead to chemicals leaching into surrounding soil and groundwater. Once released, PFOS and PFOA are highly mobile, traveling through soil, water, and air. They can contaminate groundwater and drinking water wells. These compounds are also found in wastewater treatment plant effluents, sewage sludge, and landfill leachates, contributing to their pervasive presence in ecosystems.
Health and Ecological Effects
Exposure to PFOS and PFOA can lead to a range of adverse health outcomes in humans. Studies have linked PFOA exposure to increased risks of kidney and testicular cancers. Both PFOS and PFOA have been associated with elevated cholesterol levels, liver enzyme changes, and suppressed immune system responses, including decreased vaccine effectiveness in children.
Additional health concerns include thyroid disorders, pregnancy-induced hypertension, preeclampsia, and small decreases in birth weight. These chemicals can accumulate in human blood and tissues, with studies indicating that nearly all Americans have some level of PFAS in their blood. The persistence of these chemicals means they can remain in the human body for years.
Beyond human health, PFOS and PFOA pose significant threats to ecosystems and wildlife. These chemicals bioaccumulate, meaning they build up in living organisms and can move up the food chain, impacting diverse species. Documented ecological effects include liver damage, immune suppression, reproductive issues, and neurological impacts in various terrestrial and aquatic animals. The presence of PFAS in water can also alter soil and water quality, compromising habitats and affecting overall ecological stability.
Regulatory Efforts and Mitigation Strategies
Governments and international bodies are actively working to address the pervasive issue of PFOS and PFOA contamination. The U.S. Environmental Protection Agency (EPA) has taken significant steps, including finalizing rules in April 2024 to designate PFOA and PFOS as “hazardous substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund. This designation enables the EPA to require investigations and cleanups of contaminated sites.
The EPA also established the first-ever national, legally enforceable drinking water standards for PFOA and PFOS at 4.0 parts per trillion (ppt) in April 2024, along with other PFAS compounds. Public water systems are now required to monitor for these chemicals and implement solutions to address exceedances by 2029. Internationally, the Stockholm Convention on Persistent Organic Pollutants (POPs) listed PFOS in 2009 and PFOA in 2019, aiming to eliminate or restrict their production and use globally.
Individuals can take practical steps to reduce their exposure to PFOS and PFOA. Checking local water quality reports and using certified water filters can help address contaminated drinking water. Avoiding non-stick cookware and choosing alternatives like cast iron or stainless steel can limit exposure from food preparation. Being mindful of consumer products, such as avoiding stain-resistant fabrics and food packaging that may contain PFAS, also contributes to reducing personal exposure.