A Harvard University research team has found that U.S. municipal wastewater contains elevated levels of organofluorine. Over half were widely prescribed fluorinated pharmaceuticals, and less than 10% came from six federally regulated per- and polyfluoroalkyl substances (PFAS), which accounted for only a small fraction of the total extractable organofluorine in the samples.
The pseudonyms for PFAS are the thousands of variations of synthetic chemicals containing organofluorine frames with strongly bonded chains of carbon and fluorine atoms. In particular, its strong bond makes the molecules nonstick, and they are applied in consumer products such as cookware, the inner lining of food packaging, waterproofing, and stain-resistant carpets and clothes.
The carbon-fluorine bond is one of the strongest thus these chemicals are highly resistant to degradation in the environment. Consequently, PFAS has earned the name of forever chemicals. PFAS contamination is widespread by affecting soil and groundwater systems globally and has even been detected in the Tibetan Plateau carried there by rain. While most of the U.S. population relies on wastewater treatment facilities, even advanced processes remove less than 25% of measured organofluorine.
In their study, titled High Organofluorine Concentrations in Municipal Wastewater Affect Downstream Drinking Water Supplies for Millions of Americans researchers analyzed organofluorine levels at eight large wastewater treatment facilities with similar design capacities. Natural organofluorine is very rare in the biosphere and is not necessary for life as we know it, fluorine is the 13th most common element in the Earth’s crust.
Researchers investigated bulk and targeted methods to detect extractable organofluorine including PFAS, precursors, and fluorinated pharmaceuticals. They also simulated how wastewater discharges mixed with drinking water intake under average and low flow conditions were done with a national wastewater dilution model.
Only six regulated PFAS contributed less than 10% of the organofluorine content that could be extracted from wastewater. The measured organofluorine load was dominated by pharmaceuticals (62% to 75%). We found that none of the facilities achieved removal rates exceeding 24%.
When wastewater-derived PFAS levels were included,  researchers estimated that drinking water supplies potentially contaminated above regulatory thresholds could support the health needs of over 20 million Americans—a timely concern. This is treated wastewater release, although not the water that flows down from our home’s tap, it will ‘eventually‘ be blended into other water bodies, where it is further processed and recirculated for domestic use. Communities near rivers often rely on those rivers for water to undergo treatment before being discharged back into the river. This process repeats downstream and frequently detours for agricultural, commercial, or industrial use before returning to the water cycle.
By the time water reaches a coastal city, it may have already been purified, used, and treated hundreds or thousands of times (or at least mixed with) water. The purpose of this work was to expand upon our understanding of the magnitude and composition of such discharged organofluorine from large US POTWs (defined as those serving >10,000 people), with implications for downstream water quality.
Using wastewater influent and effluent samples from eight large POTWs with similar treatment technologies and size as those responsible for serving 70% of the US population, we developed a mass budget for EOF. We extended these measurements by developing an empirical relationship relating wastewater EOF release magnitudes across the country.
Over 4,500 publicly owned water treatment works (POTWs) exist along the Mississippi River. In a water reuse system that pumps the water downriver through 10 states in a watershed of 21 more, the eight US POTWs in this work had extractable organofluorine (EOF) concentrations in aqueous effluent of 19 to 41 nanomolar equivalents as fluorine (nM F). The measured coefficient of variance over facilities across facilities (25%) is like the range over PFAA across the United States (13 to 59%) previously reported.
The eight parent pharmaceuticals identified at all eight POTWs in this study are commonly used medications in the United States, and therefore some likely ubiquitously available in municipal wastewater. In contrast, suspect screening did not find some highly prescribed fluorinated pharmaceuticals (fluticasone, fluoxetine, paroxetine, ezetimibe, and identified human metabolites) in the aqueous phase at any of the study POTWs. To rule out the effects of losses during the extractive procedure, we confirmed these results on raw water samples.
Reference: Ruyle BJ, Pennoyer EH, Vojta S, et al. High organofluorine concentrations in municipal wastewater affect downstream drinking water supplies for millions of Americans. Proceedings of the National Academy of Sciences. 2025;122(3). doi:https://doi.org/10.1073/pnas.2417156122
