Per- and Polyfluorinated Substances (PFAS) Factsheet

The per-and polyfluorinated substances (PFAS) were previously referred to as perfluorochemicals (PFCs). PFAS are a group of chemicals used to make fluoropolymer coatings and products that resist heat, oil, stains, grease, and water. Fluoropolymer coatings can be used in such varied products as clothing, furniture, adhesives, food packaging, heat-resistant non-stick cooking surfaces, and the insulation of electrical wire. Many chemicals in this group, including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been a concern because they do not break down in the environment, can move through soils and contaminate drinking water sources, and they build up (bioaccumulate) in fish and wildlife. PFAS have been found in rivers and lakes and in many types of animals on land and in the water.

How People Are Exposed to PFAS

Some PFAS persist in the environment, and people are mostly likely exposed by consuming PFAS-contaminated water or food. Exposure may also occur by using products that contain PFAS.

How PFAS Affect People’s Health

Human health effects from exposure to low environmental levels of PFAS are uncertain. Studies of laboratory animals given large amounts of PFAS have found that some PFAS may affect growth and development, reproduction, thyroid function, the immune system, and injure the liver. Epidemiologic studies have examined a number of health effects, many that are described in Fact Sheets available at: More research is needed to assess the human health effects of exposure to PFAS.

Levels of PFAS in the U.S. Population

In the Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables, CDC scientists measured at least 12 PFAS in the blood serum (the clear portion of blood) of participants aged 12 years and older who have taken part in the National Health and Nutrition Examination Survey (NHANES) since 1999. By measuring PFAS in serum, scientists can estimate the amount of PFAS that have entered people’s bodies.

CDC scientists found four PFAS (PFOS, PFOA, PFHxS or perfluorohexane sulfonic acid, and PFNA or perfluorononanoic acid) in the serum of nearly all of the people tested, indicating widespread exposure to these PFAS in the U.S. population. The data tables showing results since 1999 can be viewed at:

Finding a measurable amount of PFAS in serum does not imply that the levels of PFAS cause an adverse health effect. Biomonitoring studies on levels of PFAS provide physicians and public health officials with reference values so that they can determine whether people have been exposed to higher levels of PFAS than are found in the general population. Biomonitoring data can also help scientists plan and conduct research on exposure and health effects.

Additional Resources

Agency for Toxic Substances and Disease Registry
Environmental Protection Agency
Page last reviewed: April 7, 2017