New research suggests that fluorinated pharmaceuticals — a category that includes well-known medications such as Prozac and Flonase — are showing up in the water supply of millions of people. These drugs and their breakdown products are technically classified as being per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” which as a chemical class is the subject of worldwide health concern.
A study published January 6 in Proceedings of the National Academy of Sciences found that the bulk of PFAS entering and exiting wastewater treatment plants is made up of these fluorinated drugs. Notably, the researchers determined that the pharmaceuticals were largely not removed from the water by conventional wastewater treatment practices.
This pharmaceutical material “doesn’t get treated in the wastewater treatment plant, and it doesn’t break down,” said Bridger Ruyle, study co-author and researcher at New York University. “And we know [these chemicals] can be re-entering drinking water supplies.”
The study estimates that this material contaminates the water supply of around 23 million Americans, Ruyle said.
These drugs enter wastewater after being excreted by people. About 50% of drinking water utilities are located downstream of a wastewater outflow plant and regularly use varying amounts of this water.
A slight majority of this material was made up of only four drugs and one of their metabolites: the arthritis medication Celecoxib (Celebrex); flecainide (Tambocor), prescribed for arrhythmia; maraviroc (Selzentry), and one of its metabolites, used to treat HIV; and sitaglipt (Januvia), a diabetes drug.
“We don’t know that much about what the exposures or health risks are” for those drinking small concentrations of this material, Ruyle said. “This study emphasizes the presence of organofluorine pharmaceutical waste in the environment and highlights the urgent need to understand what the health risks to these compounds are.”
Scientists define PFAS as any organic molecule that has at least one fully-fluorinated carbon atom, meaning one that is bonded to three chlorine atoms. Most PFAS have many more such carbon-fluorine bonds, which makes them extremely resistant to breaking down. Such bonds are almost nonexistent in nature and not essential for life.
Usually when people test for PFAS they use individual measures for specific chemicals, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), which are both known to be particularly hazardous. In April 2024, the U.S. Environmental Protection Agency set limits on those and four other PFAS for the first time. Exposure to PFAS has been linked to “deadly cancers, impacts to the liver and heart, and immune and developmental damage to infants and children,” according to the EPA.
The study found that those six types of PFAS made up on average only 7% to 8% of the mass of PFAS entering and exiting the wastewater treatment plants, however.
The researchers used a unique method in this paper to measure the total quantity of organofluorine, meaning the amount of carbon-fluorine groups. All PFAS and fluorocarbons have these chemical groups. This provides a measure of extractable organofluorine, or EOF.
This method has the advantage of providing a complete portrait of what PFAS are in the environment. The European Union has several regulations that work upon similar measures, limiting total PFAS, while the U.S. has none.
This study highlights the importance of assessing total PFAS and the kind of complex mixtures that are occurring in the environment, rather than looking at each chemical one-by-one, Ruyle said.
The study examined these chemicals at eight drinking water treatment plants (known as publicly owned treatment works, or POTWs) around the country, which are similar in size and technological methods to those which serve 70% of the U.S.
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