Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)

Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)

Per- and poly-fluorylaklyl substances (PFAS) are a group of manufactured compounds that consist of carbon-fluoride bonds that make PFAS highly stable and resistant to degradation by metabolic or environmental means. First developed in the 1940s, PFAS became widely popular and are used in a number of commercial, industrial, and consumer applications and products. Some current examples include pesticides, firefighting foams, flame retardants, additives in coatings and paints for buildings, textile products such as repellent coatings, personal care products such as cosmetics and makeup, home products such as non-stick coatings for pans, and the development of electronic and semiconductor products.

With its unique chemical and physical properties, PFAS have been designated as “forever chemicals.” Biomonitoring studies have shown that PFAS are ubiquitous in soil and water, and detected in humans. In both occupational and non-occupational settings, the routes of exposures are ingestion of contaminated food and drinking water, inhalation via air or dust particulate, or dermal contact. PFAS exposure has been reported to be associated with hepatic, cardiovascular, immune, reproductive, and developmental effects in humans and animals. Perfluorooctanoic acid (PFOA), one of the most well-studied PFAS chemicals, is associated with kidney and testicular cancers.

However, much of the scientific knowledge of the risk to humans from PFAS exposure is limited by the nature of how previous studies have been conducted. For example, some human studies did not collect any information on historical exposure. Among those that may have historical exposures, collected biological specimens such as blood, and/or have information of specific outcomes of interest, many were cross-sectional in design and thus were only able to evaluate the associations at one specific point in time. These aspects limit the ability to assess any potential relationships between PFAS exposure and health outcomes in terms of establishing causality. Despite this, the growing evidence and awareness of PFAS and detrimental health effects have motivated physicians, scientists, and public health officials about the importance of additional research and regulatory measures on PFAS.

Over the years, many epidemiologic studies have primarily examined specific PFAS compounds such as PFOA and perfluorooctane sulfonate (PFOS) due to their early discovery and past industrial usage. While other PFAS compounds exist, we focus on PFOA and PFOS due to the existing assessment within the National Health and Nutritional Examination Survey.

We present exposure data on the 95th percentile of the population, representing people with the greatest exposure. The 95th percentile level means that 95% of the population has concentrations below that level. Public health officials use such reference values to determine whether groups of people are experiencing an exposure that is unusual compared with an exposure experienced by the rest of the population. For more information, see the National Report on Human Exposure to Environmental Chemicals, published by the Centers for Disease Control and Prevention.

To calculate whether the differences between 95th percentiles for two different time points are statistically significant, we used a different statistical methodology than that used by the National Center for Environmental Health, which publishes the National Report on Human Exposure to Environmental Chemicals, from which our data are derived. Our estimates may differ slightly from those in the original report due to differences in statistical procedures used. [Methodology]

Centers for Disease Control and Prevention, National Center for Health Statistics, National Health and Nutrition Examination Survey (NHANES).

The Cancer Trends Progress Report uses NHANES data through 2017-2018. The 2019-2020 cycle was not completed due to the COVID-19 pandemic. More information is available at NHANES Questionnaires, Datasets, and Related Documentation.

There are no Healthy People 2030 targets regarding PFAS as a whole or specific PFAS compounds.

Healthy People 2030 is a set of goals set forth by the Department of Health and Human Services.

Chemical Exposures