Per- and polyfluoroalkyl substances (PFASs) are a group of anthropogenic chemicals that have been of increasing concern to the public.

Commonly known as “forever chemicals,” these compounds resist biodegradation and persist in the environment. These characteristics have resulted in the dispersal of these compounds across the globe with detectable levels having been found in surface and ground waters, including remote islands and the Arctic. The ubiquity of these compounds in the environment has resulted in the contamination of food and water, which has led to the ingestion and bioaccumulation of these chemicals in the human body. Alarmingly, PFASs have been detected at the ng/ml range in the blood serum of nearly every person tested for these compounds in the U.S.

Properties such as their persistence, resistance to degradation and ability to repel both oil and water have made PFAS compounds highly desirable for a variety of manufacturing processes. As many as 3,000 PFASs having entered into commerce since their introduction in the 1940s. PFASs have been used for the manufacture of an increasing number of goods, including carpeting, upholstery, food containers, cosmetics and aqueous film-forming foam used in fighting petroleum fires. Due to concerns about their human health effects, the two most studied and understood PFASs, perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS), have been discontinued from use in the U.S., and have been replaced by other PFASs that typically have a shorter molecular structure.

While short-chain PFASs have many of the same characteristics as their long-chain counterparts, a greater quantity of the short-chain chemicals are typically needed to achieve the same performance results as their long-chain counterparts.

Studies suggest that the discontinuation of PFOA and PFOS has led to a decrease in the amount of these substances in human blood serum in the United States. Measurements of 13 different PFASs in human plasma collected by the American Red Cross showed a measurable decline in PFOA, PFOS and perfluorohexanesulfonic acid (PFHxS) between 2000 and 2015. A study comparing PFOA, PFOS and PFHxS blood serum levels in populations of the U.S. and Australia found a consistent decline in these PFASs in both populations since the beginning of the 21st century.

Another study, using National Health and Nutrition Examination Survey data that compared serum levels and liver function, found a decrease in PFOA, PFOS and PFHxS from 2007 and 2008 to 2009 and 2010. The study’s authors attribute this decline in part to the phaseout of PFOA and PFOS in developed nations.

While considerable research is currently being conducted on health risks related to exposure to PFASs, much is still unknown. The primary pathways of human exposure are through ingestion of contaminated seafood, drinking water and dust; however, the total contribution of PFASs in humans from drinking water is unknown compared to the other exposure pathways. As for human health effects, the EPA has found suggestive evidence of carcinogenic potential for both PFOA and PFOS. Observational studies of populations exposed to high levels of PFOA and PFOS have been mixed as to their conclusions about possible health effects of exposure. Yet they do suggest correlations exist with a variety of health issues, including high cholesterol, kidney and testicular cancer, pregnancy-induced hypertension, thyroid disease, ulcerative colitis, decreased birth weight, decreased vaccine response and liver damage. Less is known about the health effects of other PFAS compounds, but research suggests that exposure to some of these compounds may also result in adverse effects.

 

Drinking water exposure

Several recent studies provide evidence suggesting PFAS exposure through drinking water is a concern. A study conducted of individuals exposed to PFOA, PFAS and PFHxS through a contaminated public drinking water supply in New Hampshire found these substances in the blood serum of more than 94% of test subjects at levels above those in the general population. While the study could not rule out other exposure routes, it determined drinking water as a likely contributor to these elevated levels. A similar study conducted in Paulsboro, New Jersey, after elevated PFAS amounts were detected in the public drinking water supply, found elevated levels of several PFASs in the blood serum of test subjects. This same study found a statistically significant association between these PFAS levels and elevated cholesterol levels. A large cohort study of more than 47,000 individuals in Appalachia who had been exposed to contaminated drinking water found an inverse association between serum levels of PFOA and PFOS to colorectal cancer (CRC), with those at higher exposure levels less likely to be diagnosed with CRC. The study posited that low exposure levels to these PFASs could contribute to CRC, while a higher exposure level provides some protection against CRC due to the hydrophobic properties of the chemicals.

While the EPA has not set a maximum contaminant level (MCL) for any PFAS compounds, in 2016 the EPA set a non-enforceable and non-regulatory lifetime health advisory level (LHA) of 70 ppt for individual or combined concentrations of PFOA and PFOS in drinking water. In the absence of a regulatory standard from the EPA, several states have taken action to set either a lifetime health advisory (LHA) or MCL for PFOA and PFOS that are lower than the level set by the EPA. Some states have also set levels for PFASs other than PFOA and PFAS. According to the Association of State Drinking Water Administrators, these differing standards of risk have resulted in confusion and concern as to what level of PFASs, if any, is safe in drinking water.

The extent of the PFAS contamination of drinking water in the U.S. is also unknown. The available data suggests PFAS contamination may be widespread. In 2012, the EPA required select water utilities to collect data on six PFAS compounds, including PFOA and PFOS, as part of the third Unregulated Contaminant Monitoring Rule (UCMR 3). Of the more than 4,000 systems tested during UCMR 3, 66 systems reported PFAS levels at or above 70 ppt. An analysis of this data estimated that more than six million individuals served by these 66 utilities were potentially receiving drinking water in exceedance of the LHA. Since the UCMR 3 does not assess smaller systems or private wells, many more individuals could be drinking water in exceedance of the LHA. Testing conducted by the Department of Defense of groundwater wells near 401 military installations suspected as being the source of PFAS contamination found that more than 60% of the tested wells were in exceedance of the LHA for PFOA and PFOS.

Much remains unknown about the risk of PFASs on human health and the extent of PFAS contamination of drinking water. Additional research is needed to understand these risks and help determine appropriate policy actions to protect human health.