Per- and polyfluoroalkyl substances (PFAS) have been in industrial and household use for 60-70 years. PFAS have been detected in parts per trillion (ppt) levels in a small percent of groundwater supplies and they are more pervasive in several other sources, such as fabric coatings, firefighting foams, diet, dust, and indoor air.
For perspective, one part per trillion is one-millionth of a part per million.
The Environmental Protection Agency produced Drinking Water Health Advisories (HAs) for two major PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), of 70 ppt individually or combined, and it appears to be conservative. For instance, EPA’s HAs for PFOA and PFOS in drinking water incorporate safety factors of 300 and 30, respectively. It assumes that drinking water would account for just 20% of the total daily exposure, because diet, air, and dust are assumed to be the dominant exposure sources.
However, many states have produced their own much lower advisory and action numbers for PFOA and PFOS. The inconsistency has resulted in public and political alarm, and something needs to be done about it.
Meanwhile, there is considerable worldwide disagreement with respect to “safe” levels. There is clearly a need for a mainstream scientific consensus on safe exposure levels from all sources, including drinking water, to avoid wasteful and non-beneficial regulatory actions.
EPA’s UCMR testing of 4864 public drinking water supplies covered most of the U.S. population. The vast majority of the water supplies and populations had no detectable amounts. Overall, 63 water systems (1.3%) reported at least one sample with PFOA and/or PFOS (separately or combined) exceeding EPA’s HA level of 70 ppt. Michigan’s newly released statewide drinking water supply survey of 1,744 community water supplies, schools, day-cares and tribal entities found 1571 with no detectable levels, 115 with less than 10 ppt, and only two (0.001%) that exceeded 70 ppt.
U.S. production of PFOS and PFOA was phased out by the 2006 Stewardship agreements between EPA and eight major manufacturers. PFOA and PFOS were once detected in virtually all blood samples in the U.S., but the frequency and concentrations have been significantly reduced with blood levels having dropped roughly 60% and 80% from 1999 to 2014, respectively.
Workers at PFAS manufacturing plants that were studied had blood levels of PFOA and PFOS that were hundreds to 1000 times higher than currently found in the general population. Detailed epidemiological studies found few possible health effects, mostly a small increase in blood cholesterol and some other endpoints.
There is considerable disagreement among health scientists on the significance of PFAS exposures. Australia’s Expert Health Panel for PFAS concluded: “There is mostly limited or no evidence for any link with human disease from these observed (exposure) differences. Importantly, there is no current evidence that supports a large impact on a person’s health as a result of high levels of PFAS exposure.”
Regarding cholesterol, it concluded that the worker epidemiological studies reported a small suggested association with cholesterol, but they could not establish whether or not PFAS actually caused higher cholesterol.
The overall goal is to be protective and cost effective, avoid unnecessary risks, and control PFAS uses to prevent further environmental contamination and prevent or reduce human exposures to existing contaminated sources that exceed the appropriate benchmarks.
It is counterproductive that numerous states are producing their own health guidance or regulations using different logic, with some advisory and action levels as low as 5 ppt.
We need consistent, expert, mainstream, and scientifically credible drinking water quality benchmarks to send the message that science and risk assessment are objective, and restore the public’s confidence in regulators. EPA has the lead national responsibility.
It should immediately initiate a time limited public process to assemble the key mainstream national and international scientific experts on PFAS and propose benchmark values. It should receive public comment and peer review prior to any revision and finalization.
This column does not necessarily reflect the opinion of The Bureau of National Affairs, Inc. or its owners.
Joseph Cotruvo’s Ph.D. is in physical organic chemistry and he is board-certified by the American Academy of Environmental Engineers and Scientists. He received the AAEES Science Award in 2019. He was the first director of EPA’s Drinking Water Standards Division after the passage of the Safe Drinking Water Act and was instrumental in the development of most existing drinking water standards and regulatory policies, and also in the introduction of the EPA Drinking Water Health Advisories.