Per-/poly-fluroalkyl substances, or PFAS, are everywhere. They are used in firefighting foam, car wax, and even fast-food wrappers. They’re one of the most toxic substances ever identified — harmful at concentrations in the parts per trillion — yet very little is known about them. PFAS, which is a class of over 3000 compounds, are only regulated at the state level, so while some states are working to aggressively tackle the problem, other states have chosen to ignore PFAS completely, leaving concentrations unknown and health risks unexplored.
This topic will be discussed at the Geological Society of America’s 2020 Annual Meeting, in a technical session which will help bring PFAS to national attention. Presentations will discuss how PFAS are released into the environment, transported through groundwater, river, and soils, and partially remediated. PFAS have been produced in the U.S. for decades, primarily for industrial use. Matt Reeves, a professor at Western Michigan University and lead author of one of the presentations, says PFAS have been labelled “forever chemicals” because they have bonds that are “among the strongest in all of chemistry.”
“It’s almost like armor…we don’t have any evidence of degradation of these compounds,” he says.
The health risks from PFAS bioaccumulation are heightened because of their toxicity at extremely low concentrations. At the federal advisory level, which is non-enforceable and was set in 2016, the EPA has deemed just 70 parts per trillion (ppt) safe; that’s like a few grains of sand in an Olympic-size swimming pool. Compare that to arsenic, a toxic element whose safe limit is 10 parts per billion — much higher than the PFAS limit. Due to bioaccumulation, fish in southeastern Michigan were found with PFAS concentrations in the parts per billion — far exceeding safe limits and prompting “do not eat the fish” signs to be posted along rivers and lakes. Health effects from PFAS are still being studied, but they potentially include increased rates of some types of cancer, hormonal disruption, and immune responses.
Michigan is receiving special attention because in July of this year, the state government enacted strict regulations for seven compounds in the PFAS family. For one compound, the highest safe limit is just 6 ppt — far lower than the EPA’s guidelines. “Michigan is the most proactive state of the nation in characterizing and studying PFAS, and with their legislation,” Reeves says. His talk highlights the PFAS cycle on land and complications with site remediation.
“Notice we don’t call it a ‘life cycle,'” he says. “It’s a perpetual cycle. We cannot break down these compounds, so there’s no ‘death.'”
Even once a PFAS source is identified, remediation is difficult. North Carolina, like Michigan, has legacy PFAS contamination from industries past. Marie-Amélie Pétré, a postdoc at NCSU, is studying how quickly PFAS are flushed from groundwater to streams. This flushing is a critical part of the water cycle that determines when residents can expect their drinking water to be safe. “Quantifying the timescale for PFAS flushing from groundwater can help predict downriver concentrations in the future,” Pétré says. “We’re the first to quantify PFAS transport… between groundwater and streams using field data. It’s such a rapidly evolving field. This ongoing discharge isn’t included in remediation plans.”
At the University of Arizona, Mark Brusseau and Bo Guo are studying PFAS in soils, which serve as a PFAS repository between groundwater and surface waters. “Concentrations of PFAS in the soil can be orders of magnitude higher than they are in the groundwater at the same location,” Brusseau says. Despite differences in state regulation, one thread is clear: PFAS are everywhere. His talk examines over 30,000 soil samples from around the world. “PFAS were found to be present at almost every site that was sampled, whether it was a metropolitan area, near an industrial source, or out in a rural area,” he says. “[They are] even in some very remote mountain areas.”
“PFAS don’t discriminate,” Steve Sliver, a co-author on Reeves’ talk and lead of Michigan’s PFAS response team, says. “The sources are pretty much everywhere.”
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