This July, a new study revealed that per- and polyfluoroalkyl substances (PFAS) — a family of potentially toxic chemicals with more than 4,700 known members — have become even more widespread in our environment than previously thought. The researchers behind the study, which was published in Environmental Science and Technology, detected 11 different PFAS compounds all the way up in the Arctic Ocean, including the first officially confirmed instance of certain relatively newer members of the PFAS family in such a remote body of seawater.
The new study provides a snapshot into the sheer ubiquity and pervasiveness of these bio-accumulative compounds, called “forever chemicals” because of their stubborn persistence in the environment. Just how widespread are they? We’re still learning, but they’ve appeared in such far-flung places as the polar bears of East Greenland. Back home, the findings of an Environmental Working Group (EWG) study helped lead the nonprofit watchdog organization to posit that PFASs are probably detectable in “all major water supplies” in the U.S.
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“This is a global problem,” said Pamela Miller, executive director of Alaska Community Action on Toxics, an environmental health and justice organization, which released a report last year that confirmed PFAS contamination was present in Alaska at nearly every site investigated where aqueous film-forming foam — a prolific source of PFAS drinking water contamination — had or is currently used. “When these chemicals show up in the Arctic, something’s very wrong,” Miller added.
Known human health impacts from exposure to some PFAS chemicals include certain cancers, liver damage, thyroid problems and increased risk of asthma. As endocrine disrupters, these chemicals have been linked to increased risk of severe COVID-19. Perhaps the two best known members of the family, PFOA and PFOS, are no longer manufactured in the U.S. due to the human health risks they pose, but experts fear that global emissions of these chemicals remain elevated due to manufacturing shifts to Asia. What’s more, there’s a growing body of research to suggest that some of their chemical replacements pose similar human health concerns.
Nor are PFAS compounds easy to avoid, due to the fact they’re found in an array of everyday items, such as food packaging, carpets and clothing. In a common refrain, communities of color and low-income communities appear to be disproportionately impacted by PFAS exposures.
Because what goes up must come down, the question that many experts are currently grappling with is this: How exactly are PFAS compounds traveling and being dispersed across the globe? Emerging research suggests that one important pathway is through the air and in rainwater. Indeed, the Arctic Ocean study published in July speculated that certain PFAS compounds were entering the water from atmospheric sources rather than from ocean circulation. This is a major headache for regulators as they attempt to remove these highly soluble chemicals from the environment — especially bodies of drinking water.
Indeed, regulators will struggle to enact effective water quality standards surrounding PFAS contamination “if we find that a significant portion is depositing from the atmosphere,” said Martin Shafer, a senior scientist and principal researcher with the National Atmospheric Deposition Program (NADP), based at the University of Wisconsin-Madison, and the nation’s longest-running program for monitoring the chemistry of precipitation. First, however, “that route has to be appreciated and better understood,” he added.
Eric Uram, chair of the Sierra Club’s Toxics Committee, performed an analysis of EWG’s data on PFAS and found a significant portion of the 44 places sampled were supplied either in whole or in part by bodies of surface water. “We’re finding out that it’s easier to dispose of these chemicals improperly than it is to manage them successfully,” he noted.
Though still fairly limited, current scientific literature points to PFAS compounds entering the atmosphere a variety of ways, like industrial and landfill releases, emissions from treated wastewater and concentrated waste, along with water evaporation. This study suggests that sea spray could be another “important” possible conduit. At the same time, there remain many unanswered questions surrounding what happens to these chemicals once they’re up in the air: How long do they remain there, for example, and how do they behave chemically? How widely dispersed are they? And how many of them are scrubbed out of the atmosphere during a rain event?
The bulk of research thus far has focused on rainwater. Last November, Shafer and his fellow researchers unveiled at a national science symposium in Colorado the findings of a study in which rainwater samples were taken from 30 different sites primarily on or near the east coast of the U.S. Each sample contained at least one of the 36 different compounds being studied. And while the bulk of the samples contained relatively low levels of PFAS — typically less than 1 nanogram per liter (ng/l) — the highest total concentration in a single sample was nearly 5.5 ng/l. That concentration is above or near potential actionable drinking water thresholds at the state level, with various jurisdictions pursuing much more rigorous drinking water standards than at the federal level, which has a drinking water health advisory level of 70 ng/l for combined PFOS and PFOA. Last year, for example, Wisconsin proposed a preventative action limit of 2 ng/l for combined PFOS and PFOA.
A growing number of institutions are plunging into the PFAS issue, seeking a better understanding of the problem’s pervasiveness. Researchers out of the University of North Carolina (UNC) Wilmington spent a year collecting wet and dry deposition samples at a variety of locations across the state. Dry deposition is particulate matter too heavy to remain airborne. While the findings are currently undergoing peer review before publication, Ralph Mead, a professor at UNCW, was able to share some details.
The researchers targeted a list of 20 different PFAS compounds, but “routinely analysed for seven,” said Mead. They found that while some of the samples were below the detection limit, “the majority of the samples did contain at least one of our targeted compounds,” according to Mead. The highest concentration of an individual PFAS compound in rainwater was around 10 parts per trillion, said Mead. “It’s small,” he said, “but it’s still there.”
Looking at international research, a paper published last year presented the findings of a rainwater monitoring study that took 39 samples from 28 cities across mainland China. Researchers found “ubiquitous” levels of certain PFAS compounds from a total of 22 studied. Still, experts stress yawning data gaps. How, for example, are toxic PFOA and PFOS still routinely found in the atmosphere considering U.S. industry has phased them out? In the NADP’s findings from last year, for example, both PFOS and PFOA were among the compounds most frequently detected.
One possible reason, said Mead, is a possible “secondary source” releasing these chemicals into the atmosphere — commercial products perhaps that have arrived from other countries that haven’t banned the two chemicals. The other possible explanation, he warned, could be “photochemical transformation of a precursor that is photo-oxidizing to form PFOS or PFOA.” In other words, Mead and others suspect that certain replacement PFAS compounds introduced into the market undergo a chemical change in the atmosphere that sees them transform into chemical chains like PFOS and PFOA — another potential headache for regulators, and a potential danger to all of us.
Another reason could be that PFOS and PFOA act like “surfactants” that prefer to exist at the water surface said Barbara Turpin, professor and chair of the Department of Environmental Sciences and Engineering within the Gillings School of Global Public Health at UNC Chapel Hill, who has conducted her own research into atmospheric levels of PFAS. In the case of contaminated ocean water, for example, the physical act of waves breaking and bubbles bursting can send contaminated droplets into the atmosphere through sea spray, she said.
Throughout 2019, Turpin and her fellow researchers studied 34 separate PFAS compounds at five separate sample sites in North Carolina, each a distance from any known PFAS source. The findings are currently undergoing peer review before publication, but Turpin shared a finding: There’s seasonal variability in the different PFAS compounds and levels detected, which provides researchers another useful avenue of pursuit as they look skyward for answers.
In terms of danger from exposure, “I’m not worried about breathing PFAS in outdoor air,” said Turpin, who explained that she and other researchers at UNC Chapel Hill have in the pipeline a Sloan Foundation-funded study zeroing in on atmospheric PFAS levels within the home. “If I’m worried about PFAS, I’m worrying about PFAS in my drinking water, and PFAS that I’m exposed to in my home or my workplace.”
Indeed, separate studies from Canada, the U.K. and Germany found that atmospheric levels of certain PFAS compounds were typically higher indoors than outdoors. “They’re not natural in the environment — they’re made to be in consumer products,” Turpin said, pointing to everyday items like carpets and furniture. “That’s why concentrations are actually higher indoors than outdoors.”
Shafer also outlined a series of ongoing and future PFAS-related studies, one of which comprises the monitoring of four wastewater treatment facilities in Wisconsin. Already underway, the aim of the study is to better understand how these plants play a role in releasing PFAS chemicals into the water, earth and air, as well as to learn about any chemical transformations that these compounds undergo throughout the various treatment processes. The NADP, the EPA and state environmental agencies have also initiated a two-year rainwater monitoring program in eastern states — what Shafer calls the “most long-term focused study for PFAS the nation’s ever done.”
Weekly samples will be taken at sites located in North Carolina, New Jersey, New York and Maine. Why is such a broad geographic network of monitors necessary? A study of PFAS releases from certain manufacturing plants in North Carolina indicated “long-range atmospheric transport and deposition in rainwater of PFAS in the eastern U.S.,” said Shafer. “Scientists have found that there’s some unique compounds that came out of some of those manufacturing facilities [in North Carolina], and they can trace it in the sediment all the way up to New Hampshire.”
Interestingly, the EPA will also be conducting what is called a “non-targeted analysis” of the rainwater samples, said Shafer. In other words, they’ll be looking at a broad array of PFAS compounds — potentially thousands — in the collected rainwater, rather than targeting just a relatively small number.
“It’s scary” how ubiquitously these chemicals are appearing in the environment, said Tasha Stoiber, a senior scientist with EWG. “It has the potential to just be basically everywhere.”