PFOs

PFOS, or perfluorooctane sulfonic acid, is a synthetic fluorinated organic compound in the broader class of PFAS (per- and polyfluoroalkyl substances). It is an eight-carbon chain sulfonic acid (C8HF17SO3−) that is highly persistent in the environment and tends to bioaccumulate in wildlife and humans. It is typically discussed as a representative member of PFAS due to its prominence and well-studied properties.

PFOS has been used since the mid-20th century in a wide range of products for its water- and grease-repellent properties, including textiles, paper coatings, leather treatments, and many other consumer and industrial applications. It also served as a key component in aqueous firefighting foams (AFFF). Production and usage have declined in many regions because of health and environmental concerns, with safer alternatives and regulatory controls adopted.

Environment and exposure: PFOS is extremely persistent and can undergo long-range transport in air and water. It accumulates in sediments and biota and has been detected globally, including in remote ecosystems. Human exposure occurs mainly through drinking water, food, consumer products, and occupational sources. The chemical’s long biological half-life contributes to its persistence in the body.

Health and regulation: Epidemiological and animal studies have linked PFOS exposure with effects on cholesterol, thyroid function, immune responses, and development, though causal relationships are complex and context-dependent. PFOS is listed under the Stockholm Convention on Persistent Organic Pollutants, with international measures to reduce release and use. Many countries have enacted restrictions or phaseouts.

Detection and remediation: PFOS is routinely measured by LC-MS/MS. Remediation of contaminated water and soils often uses activated carbon, ion exchange, or advanced membrane processes; prevention through substitution with safer alternatives remains a priority.