Traces of 18 unregulated chemicals were found in drinking water from more than one-third of U.S. water utilities in a nationwide sampling, according to new, unpublished research by federal scientists.
Included are 11 perfluorinated compounds, an herbicide, two solvents, caffeine, an antibacterial compound, a metal and an antidepressant.
Researchers from the U.S. Geological Survey and the Environmental Protection Agency analyzed single samples of untreated and treated water from 25 U.S. utilities that voluntarily participated in the project.
Twenty-one contaminants were detected – mostly in low concentrations of parts per trillion – in treated drinking water from at least nine of the utilities. Eighteen of the chemicals are not regulated under the federal Safe Drinking Water Act so utilities do not have to meet any limit or even monitor for them.
“The good news is the concentrations are generally pretty low,” said Dana Kolpin, a research hydrologist with the USGS who participated in the study.
“But,” he added, “there’s still the unknown. Are there long-term consequences of low-level exposure to these chemicals?”
For many of the contaminants, little is known about any potential human health effects of low doses. But one of the perfluorinated compounds, known as PFOA, has been linked to a variety of health problems, including cancer, among people in communities where water is contaminated by a chemical plant in West Virginia.
Of 251 chemicals, bacteria, viruses and microbes the scientists measured, 117 were not detected in any of the treated drinking water. Twenty-one were found in water from more than one-third of the 25 utilities (nine or more) and 113 were found in less than one-third (eight or fewer).
EPA research chemist Susan Glassmeyer, who led the project, said the utilities, which remain anonymous, represented a mix of large and small, and used different water treatment technologies.
Preliminary findings of the study, which is expected to be published next year, were presented by the scientists at a toxicology conference in Nashville last month.
While studies increasingly report newly emerging contaminants in wastewater, there has been little data on which ones are in drinking water.
Four of the chemicals found in the samples – the metal strontium, the herbicide metolachlor, PFOS and PFOA – are on the EPA’s list of chemicals under consideration for drinking water standards. The EPA plans to make decisions regarding at least five of the contaminants on its list next year.
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