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Persistent Pollutants

Reactions: Drinking-water advisories for PFOA and PFOS, and Iranian protests

October 15, 2022 | A version of this story appeared in Volume 100, Issue 37


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)

Iranian protests

“Woman, life, freedom” is currently the main chant in the streets of Iran. This is in response to the killing of a 22-year-old woman, Mahsa “Zhina” Amini, while in custody by the Islamic Republic of Iran’s “hijab police.” On Sept. 13, Mahsa was arrested for allegedly violating hijab laws. While in custody, Mahsa was cruelly assaulted, according to eyewitness reports, fell into a coma, and perished shortly after. After this tragedy, Iranians led by women began protests demanding justice and freedom. Iranian women who have been systematically oppressed for the past 43 years are fighting for their rights.

Iran’s regime is trying to suppress the rallies by using street violence, including killing its own citizens, conducting mass arrests, and attacking students in universities. Protests have occurred in over 150 cities across the world, and politicians have condemned the oppression in Iran. Students of more than 110 universities have issued statements in protest of the arrests of classmates and professors and have refused to attend classes. They have invited the people of Iran to join them in a strike against Iran’s regime.

Limitations on Iranian women go beyond the mandatory hijab. By law, women in Iran need permission from their father, husband, or legal guardians to obtain a passport to leave the country, including for participating in conferences or pursuing studies. Women in Iran face serious limitations in pursuit of science, technology, engineering, and mathematics (STEM). They are systematically held back and make up only a small fraction of the workforce in STEM. Iran’s government has made it particularly difficult for them to flourish in a safe, free, and fair environment. Iran’s politics has resulted in the exodus of highly educated Iranians, including women who want to thrive in STEM, over the past few decades. A great example of such an emigrant is mathematics professor Maryam Mirzakhani of Stanford University, who in 2014 became the first female winner of the Fields Medal.

As members of the chemistry, biochemistry, and chemical engineering communities around the world, we are raising our voices about the current events in Iran. We strongly condemn the government’s crackdown. People of Iran, and Iranian women in particular, are peacefully citing human rights issues, political repression, corruption, and economic hardship and are being brutally silenced by the regime. We declare our solidarity with this women’s movement in Iran and fully support all women facing oppression.

104 Iranian and 24 non-Iranian chemists, biochemists, and chemical engineers from across the globe

Editor’s note: The signatories of this letter have asked that their names be withheld to protect friends and family residing in Iran.



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