Chemical & Engineering News: Letter to the Editor of PFAS Drinking Water Advisories

October 18, 2022


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Council member Joe Cotruvo recently submitted a letter to the editor of Chemical & Engineering News on the EPA’s drinking water health advisories for PFOA and PFOS, relative to the World Health Organization’s standards. Cotruvo, along with his co-authors Susan Goldhaber and Andrew Cohen, implores the EPA to “reexamine its assessments to provide a more credible scientific basis for its health advisories.”

Read the full letter here.

Reactions: Drinking-water advisories for PFOA and PFOS LETTERS TO THE EDITOR

PFOA and PFOS limits

The US Environmental Protection Agency’s drinking-water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are 0.004 parts per trillion (ppt) and 0.02 ppt, respectively, down from 70 ppt. They are far below what can be measured in drinking water. Several other countries have advisory levels at 100 ppt and higher. Some states have levels in single-digit parts per trillion. The very low EPA health advisory numbers cause greater public concerns and mitigation costs without benefit.


Everyone agrees that per- and polyfluoroalkyl substances (PFAS) are environmentally and biologically persistent and should be managed. Exposures occur from many sources, including household products and fabrics, some foods, and food contact containers. Their manufacture, uses, and exposures are being reduced by company and government agreements from the early 2000s. Human blood levels of PFOA and PFOS in the US are more than 70–85% less than they were in 1999. Some drinking waters are exposure sources, usually at low parts per trillion, especially some groundwaters, where they may persist for many years.

The EPA’s calculations are based partly on a study in the Faeroe Islands with an inverse relationship between child blood levels and antibody titers for diphtheria and tetanus. There is debate on the study’s applicability. Even if the finding is valid, the US Centers for Disease Control and Prevention’s data show no relationship with cases in the US. Cases of diphtheria are extremely low. Vaccinations are very effective, so those health advisories are protecting against a nonexisting consequence at high cost.


The advisories’ credibility is doubtful, and those unmeasurable numbers raise public concern and result in major expenditures in the over 150,000 public water systems in the US. They also misdirect drinking-water priorities and expenditures that should deal with decaying water distribution systems and water-related legionellosis, a deadly waterborne disease.


The EPA must reexamine its scientific risk assessments and provide a more credible scientific basis for its health advisories. Serious peer review is essential.

The World Health Organization, in its draft PFAS document, reviewed the health and exposure data and concluded that there are inconsistencies and uncertainties in the studies. It proposed drinking-water values of 100 ppt for PFOA and PFOS and 500 ppt for total PFAS.

PFAS are an international problem. The EPA should participate in an international expert process for comprehensive management and a consensus on realistic protective values for PFAS chemicals.

Joseph A. Cotruvo (Washington, DC), Susan Goldhaber (Raleigh, North Carolina), and Andrew Cohen (Westfield, New Jersey) 

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