Harvard researchers have discovered large quantities of previously undetected chemical compounds known as PFAS in six watersheds on Cape Cod. Chronic exposure to the so-called “forever chemicals” — which can be found in water-resistant clothing, stain-resistant furniture, and nonstick cookware — has been linked to cancer, diabetes, and low infant birth weight.
The researchers focused on identifying PFAS compounds in water samples collected between August 2017 and July 2019 from the Marstons Mills, Mashpee, and Santuit watersheds, along with the Childs, Quashnet and Mill Creek watersheds, which are downstream from Joint Base Cape Cod and the Barnstable County Fire Training Academy. Those sites historically used extensive amounts of fire-retardant foams, which are a major source of PFAS.
“We found PFAS in every sample that we collected from all watersheds,” said lead author and Harvard graduate student Bridger Ruyle. “The concentrations in the watersheds that had historical firefighting use had levels that were 10 or 100 times higher than in the watersheds that had no historical use of the firefighting foams.”
Total concentrations of PFAS present in these watersheds were above state maximum contaminant levels (MCLs) for drinking water safety. However, he added, the water samples were taken from non-drinking water sources, though they could affect fish.
"In the watersheds with firefighting training, the average concentrations of the six chemicals that Massachusetts has regulated in drinking water were 400 parts per trillion. The standard is 20 parts per trillion," Ruyle said. "In the watersheds without known firefighting training, the average concentrations were 10 parts per trillion.”
By developing a new method to capture and characterize all PFAS, the research team also found large amounts of unidentified PFAS that couldn’t have originated from these foams.
“Our big surprise is that we thought that firefighting foams would be the biggest source because they contain so much PFAS and were used for so long at these sites,” he said. “But it turns out that there are now more sources that we just weren't aware of and we need to look more into it.”
In fact, between 37 percent and 77 percent of the PFAS could not be attributed to the firefighting foams. “This has huge ramifications for not only our understanding of human exposure,” Ruyle said in a statement, “but also for how much PFAS is discharging into the ocean and accumulating in marine life.”
Traditional testing methods are completely missing these previously unknown PFAS, he added, creating questions about whether municipalities are effectively filtering the chemicals out of drinking water.
“On the municipal level, they use large activated carbon treatment beds to clean PFAS,” he said. “Whether or not those are effective at capturing these unknown compounds, we don't know because we are still just finding out that they exist in the first place.”
Future study will explore the source of the previously unknown PFAS and whether municipalities are effectively removing the chemicals from drinking water sources.
“We should be concerned that there are even more PFAS,” Ruyle concluded in an email, “and should prioritize whether or not the safety measures we have taken are effective at addressing these PFAS”
The research will be published in the journal Environmental Science & Technology.