What is PFOS/PFOA?

PFOS and PFOA are perfluoroalkyl substances (PFASs), a family of man-made chemicals that have been used for many years in various products such as carpets, clothing, fabrics, paper packaging for food and other materials that are resistant to water, grease and stains. They have also been part of the chemical makeup of aqueous film forming foam (AFFF), an important product used by military and civilian firefighting units since 1970 to suppress fuel fires.

What are some different terminology being used to describe PFOS/PFOA?

Perfluoroalkyl substances (PFAS) are a family of hundreds of human-made chemicals as described above. The two best known groups of this family of chemicals are the perfluorocarboxylic acids (PFCAs), which include perfluorooctanoic acid (PFOA), and the perfluorosulfonates (PFSAs), which include perfluorooctane sulfonate (PFOS). PFOS/PFOA may also be referred to as Perfluorinated Compounds (PFCs).

What is EPA’s Lifetime Health Advisory levels for PFOS/PFOA in Drinking Water?

In May 2016, the Environmental Protection Agency (EPA) released a Lifetime Health Advisory (LHA) for PFOS/ PFOA in drinking water.  This LHA represents a concentration in drinking water that is not expected to produce adverse effects with daily consumption over an entire lifetime. The PFOS/PFOA LHA is 70 parts per trillion (ppt) individually or combined if both are detected in drinking water.  The EPA LHA levels include a significant margin of safety to ensure they are protective of the most sensitive sub-populations while drinking the water over a lifetime.  The EPA LHA levels are based on the effects of PFOS/PFOA on laboratory animals and epidemiological studies of human population.

Is PFAS still being produced?

PFAS may broadly be separated into two categories: short-chain and long-chain. Long-chain PFAS, including PFOS and PFOA, contain more carbon atoms than short-chain PFAS. In general, short-chain PFAS are still being produced worldwide, but the production of long-chain PFAS has declined over the past 15 years. For example, the largest U.S. manufacturer of PFOS voluntarily stopped producing it in 2002. However, other countries still produce PFOS, and it can be imported into the United States in limited quantities. In 2006, EPA and major companies in the PFAS industry launched the 2010/2015 PFOA Stewardship Program in which the eight leading manufacturers of PFOA agreed to a voluntary phase-out of PFOA.

As companies have stopped producing long-chain PFAS, short-chain PFAS have replaced them in many cases. Short-chain PFAS have many of the same unique properties as long-chain PFAS. Some (but not all) short-chain PFAS do not remain in the body as long as long-chain PFAS. As a result, they are thought to be a less-toxic alternative to long-chain PFAS. However, the toxicity and environmental impacts of short-chain PFAS have not been thoroughly researched, and more research is needed to demonstrate their potential effects. 

What are the more commonly studied PFAS?

PFAS are a class of chemicals; 8 have been studied more than the others: PFOA (perfluorooctanoic acid), PFOS (perfluorooctane sulfonate), PFHxS (perfluorohexane sulfonate), PFOSA (perfluorooctane sulfonamide), PFNA (perfluorononanoate), PFDeA (perfluorodecanoate), Et-PFOSA-AcOH 2 [(N-ethyl-perfluorooctane sulfonamido) acetate], and Me-PFOSA-AcOH 2 [(N-methyl-perfluorooctane sulfonamido) acetate]. Scientists know the most about PFOS/PFOA. Less is known about the other PFAS.

What are health advisory levels?

Health advisory (HA) levels identify the concentration of a contaminant in drinking water at and below which adverse health effects are not anticipated to occur over specific exposure durations (e.g., 1 day, 10 days, a lifetime). HALs serve as informal technical guidance to assist federal, state, and local officials, and managers of public or community water systems in protecting public health when emergency spills or other releases occur. A HA provides information on the environmental properties, health effects, analytical methodology, and treatment technologies for removing drinking water contaminants.

What does part per trillion (ppt) in drinking water mean in simple terms?

One (1) ppt is equivalent to one (1) drop of water in 20 Olympic-sized swimming pools.

Are there advisory numbers for other PFAS (beyond PFOS/PFOA)? 

While EPA does not have health advisory levels for other PFAS, there are some states that have developed screening levels beyond PFOS/PFOA.