New Delhi: Levels of per- and polyfluoroalkyl substances, or PFAS, in American drinking water may be substantially higher than official monitoring data indicate, a new study has found. PFAS are commonly known as “forever chemicals” because they break down extremely slowly in the environment, allowing them to accumulate in soil and water.
Published in Cell Reports Sustainability, the study reanalysed data from the Environmental Protection Agency (EPA) and found that conventional methods of calculating average contamination levels may overlook significant amounts of these persistent chemicals.
PFAS are synthetic substances used in various consumer products, including non-stick cookware, cosmetics, and food packaging. Exposure to certain PFAS has been linked to several health problems, including cancer, cardiovascular conditions, and reproductive and developmental complications.
Researchers led by Gehendra Kharel of Texas Christian University examined approximately 1.86 million test results from 9,991 community water systems. The team found that nearly 98 per cent of the tests were marked as below the laboratory reporting limits for PFAs. These limits represent the lowest concentrations laboratories can reliably measure and report, rather than indicating that a chemical is entirely absent.
When calculating average contamination levels, results below these limits are frequently treated as zero. Using statistical models to estimate the concentrations that conventional reporting methods exclude, the researchers found that existing calculations captured only 44 per cent of the estimated average PFAS concentration across the water systems examined. The actual average could be more than twice the figure implied by conventional calculations.
Are current monitoring methods inadequate?
The findings raise questions about whether existing reporting practices adequately represent PFAS contamination. The EPA requires public water systems to monitor 29 PFA compounds and has established legally enforceable drinking water limits for six of them. These include perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), each subject to a limit of 4 parts per trillion.
The researchers argue that treating measurements below reporting limits as zero can obscure the presence of these chemicals and lead to underestimates of contamination. They recommend clearer reporting of laboratory limits, greater transparency about uncertainty in estimated concentrations, and additional testing where necessary.
However, the study does not establish that individual water systems violate federal safety standards or that people are exposed to higher concentrations than previously believed. Its estimates are based on statistical models rather than direct measurements of the concentrations below reporting limits. The researchers also examined water entering distribution systems, rather than the water people ultimately consume.
Bruce Rittmann, director of the Biodesign Swette Center for Environmental Biotechnology at Arizona State University, said the findings highlight the need for more sensitive testing methods and the recognition of PFA compounds beyond PFOS and PFOA.
(Edited by Prasanna Bachchhav)
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