On May 14, EPA announced that it would keep the current drinking water regulations for PFOA and PFOS, two “forever chemicals” at four parts per trillion (ppt), and will rescind and reconsider the rules for PFHxS, PFNA, and “GenX chemicals” at 10 ppt, and a Hazard Index with a limit of 1 (unitless) for any mixture of two or more of PFNA, PFHxS, PFBS, and “GenX chemicals.”
What are the hits and missed opportunities of this decision?
The Hits
Although EPA did not state its reason for rescinding the regulations for PFHxS, PFNA, and “GenX chemicals,” there is no scientific basis to support these regulations.
- These regulations were based on animal studies, which are not helpful in evaluating the effects on humans because the mechanisms by which they cause toxicity are not relevant to humans. (Rats and mice are much more sensitive than humans to this mechanism).
- It has been estimated that the doses used to cause liver toxicity in animal studies are approximately 700 to 14,000 times higher for PFOA and 11 to 23 times higher for PFOS than the levels found in the blood of the average American.
EPA also rescinded the regulation for the Hazard Index (HI) for the mixture of PFAS.
The Hazard Index is the ratio of the PFAS in drinking water divided by the level below which the EPA has determined is unlikely to cause adverse health effects. Individual PFAS ratios are then summed across the mixture to yield the Hazard Index [1]. If the HI is less than 1, the EPA considers the mixture to comply with the regulation.
EPA was correct in rescinding this regulation because:
- It is not in compliance with the Safe Drinking Water Act, which specifies that, in setting primary drinking water regulations, the EPA should set a maximum contaminant level (MCL) [2] if it is technically and economically feasible to measure the contaminant in drinking water. If it is not feasible, EPA should set a treatment technique. Since it is technically and economically feasible to measure these contaminants by statute, theEPA should have set MCLs, not a Hazard Index.
- It is not correct scientifically. The Hazard Index is based on dose additivity. The EPA published a white paper that says that dose additivity should be used only if the chemicals exhibit similar mechanisms of action. This is not the case for PFAS. An expert panel concluded that “all PFAS should not be grouped together and that it is inappropriate to assume equal toxicity/potency across the diverse class of PFAS,” making the use of the Hazard Index inappropriate.
Miss on PFOA and PFOS
EPA missed the mark by not removing the regulations for PFOA and PFOS. EPA did not explain their reasons for retaining the regulations; perhaps it was because the PFAS Action Plan began under the first Trump Administration, or EPA was wary of public pushback, but scientifically, this was a clear miss.
An outstanding new article in Critical Reviews in Toxicology presents a comprehensive discussion of the EPA’s misconceptions about the health hazards of PFOA and PFOS in their drinking water regulation. This article examined the scientific literature and stakeholder comments, identifying fifteen misconceptions that had a weak scientific foundation and formed the basis for drinking water regulations. Among them:
Misconception #1: Current human or animal studies provide adequate evidence that PFOA/PFOS harms the immune system, developing fetus, cardiovascular system, and the liver.
Although the EPA recognized that “epidemiology studies on PFOA/PFOS frequently showed inconsistent, statistically insignificant results and lacked consistent dose-response relationships,” they relied on flawed and inadequate studies to reach their conclusions.
- Immune effects: EPA relied on two studies from the Faroe Islands on diphtheria antibody levels, which are deeply flawed and not relevant to the US population.
- The developing fetus: EPA relied on three flawed studies that linked decreased birth weight to environmental factors while ignoring studies that did not show an association.
- Cardiovascular effects: EPA ignored the evidence reporting no increase in cardiovascular disease associated with PFOA/PFOS and relied on studies showing modest increases in total cholesterol.
- Liver toxicity: EPA used increases in alanine aminotransferase (ALT) and no other biomarker to demonstrate liver effects, ignoring the studies showing no association between PFOA/PFAS and liver disease.
Misconception #2: PFOA/PFOS causes cancer.
The EPA asserted that there was evidence for kidney and testicular cancer in humans and other types of cancer in rats while ignoring larger occupational studies that did not show increased cancer in workers who were exposed to greater levels of PFOA/PFOS than the general population. The lack of evidence of a cancer risk is supported by the independent scientific committees that advise the UK governmental agencies that concluded that there was “no evidence between exposure to PFAS and cancer risk” and the European Food Safety Authority that found little evidence linking PFOA/PFAS exposure to increased cancer risk.
Misconception #3: The regulation will prevent thousands of deaths and hundreds of thousands of illnesses.
It is nearly impossible to demonstrate that any population in the US who are currently exposed to PFAS in drinking water is at increased risk of cancer or other non-cancer effects. The EPA quantified its benefits based on the number of theoretical cases of cancer, illness, and premature deaths expected to be avoided due to the PFAS regulation. EPA used estimated deaths and illnesses avoided from cardiovascular disease, low birth weight, kidney, liver, and bladder cancer, assuming that all the illnesses and deaths from these diseases and conditions were due to PFAS exposure. This was clearly data “overreach,” resulting in misleading results that were the foundation for justifying the regulation.
Misconception #4: The regulation will significantly reduce PFAS blood concentrations in the US population in the coming years.
This is unlikely to occur because 80% of PFAS exposure is from sources other than drinking water, primarily from the diet, particularly seafood. Blood concentrations of PFOA/PFOS have decreased considerably over the past two decades, declining by more than 70 percent for PFOA and 80 percent for PFOS, so reducing drinking water concentrations to 4 ppt is unlikely to lead to measurable changes in PFAS blood levels.
Misconception #5: Water utilities will have adequate federal grants to meet the costs of the regulation.
The EPA estimated that the initial capital costs of the regulation are approximately $14.4 billion. They stated that the $11.7 billion appropriated in the Infrastructure Law, along with an additional $5 billion for emerging contaminants, will likely be sufficient to support a substantial portion of the initial capital costs of the rule. However, the American Water Works Association (AWWA), conducting its own independent investigation, estimated that public water systems would require $50 billion in upgrades over the next 20 years to meet the costs of the regulations. This did not consider the designation of PFOA and PFOS as “Hazard Substances,” which would cost an additional $3.5 billion a year in disposal costs.
In the era of DOGE and pressure on the federal budget, claims of sufficient resources to cover the cost of regulation seem highly speculative. More likely, this will turn into an unfunded mandate for the States.
The EPA missed an opportunity to rectify the regulation and get the underlying science correct. As I wrote in Health Advisories, the original sin was when the EPA set its Health Advisories at four ppt based on inadequate science. We are left in the unenviable position of depending on the courts to get it right when the responsibility should have been with the EPA. If the courts fail to correct what the EPA didn’t, this regulation will unleash a horde of class-action lawsuits and increased costs for millions of American consumers.
[1] For example HI = [HFPO] in ng/L /10 ng/L + PFBS (ng/L)/2000 ng/L + PFNA (ng/L)/10 ng/L + PFHxS (ng/L)/10 ng/L = 1 where ng is nanograms and ng/L is nanograms per liter.
[2] A Maximum Contaminant Level (MCL) is the maximum permissible concentration of a specific contaminant in drinking water supplied to consumers.
