How can you protect yourself against ‘forever chemicals’ in drinking water?
A study of homes in the Triangle and Wilmington areas has re-emphasized that reverse osmosis water filters are the most effective way for consumers to remove “forever chemicals” from their drinking water, researchers from Duke and N.C. State University said Wednesday.
The team, led by Duke environmental toxicologist Heather Stapleton and N.C. State environmental engineer Detlef Knappe, tested water from 61 homes in the Triangle area and 12 around Wilmington, taking samples before and after water was treated. Researchers tested those samples for a variety of per- and polyfluoroalkyl (PFAS) chemicals.
Reverse osmosis and dual-stage filters captured more than 90% of most PFAS chemicals and about 75% of GenX, the substance that has raised concern throughout the Cape Fear region in recent years, the team announced in findings published in the peer-reviewed journal “Environmental Science & Technology Letters.”
By comparison, filters that used activated carbon, such as those found in Brita filters and refrigerators, were less effective. The carbon-based filters removed 60% to 70% of long-chain PFAS chemicals and about 41% of the short-chain chemicals, a category that includes GenX and others that researchers are finding with increasing frequency. There was, Stapleton noted, wide variability among the activated carbon filters.
“The reason these removal efficiencies are so variable is still very unclear to us,” Stapleton said during a Wednesday briefing. “Many of these filters are proprietary in nature. We know that they’re activated carbon-based, but it could vary depending on the volume mass of activated carbon, the size of that activated carbon.”
Stapleton urged people already using filters or considering them to replace them as recommended. In some instances, Stapleton said, researchers found that water contained more PFAS molecules after being treated because the filter was saturated, meaning chemicals were rinsing from the filter into the drinking water.
“What’s leading to saturation of the filters is probably the volume of water that goes through your filter and the other constituents of the water, other organic compounds in particular,” Stapleton said.
PFAS are often dubbed “forever chemicals” because they do not readily degrade in the environment. The chemicals have been found at high levels throughout North Carolina, in places ranging from Pittsboro to Wilmington, as well as in a wide swath of land around Chemours’ Fayetteville Works in Bladen County.
According to the Environmental Protection Agency, PFAS chemicals can harm human health if they are allowed to accumulate within the body. Research indicates that short-chain PFAS likely do not build up in the human body like some similar chemicals. That does not mean the chemicals are safe, though, as the N.C. Department of Health and Human Services reports animal studies of GenX, which was found in drinking water throughout the Lower Cape Fear River, indicates the liver, immune system and pancreas are all susceptible.
N.C. State’s Knappe led the 2016 study that showed GenX, which Dupont and then Chemours used to replace a proven-toxic long-chain chemical, was making its way through Wilmington’s water treatment system and into the region’s drinking water. In the days that followed, Knappe recommended that Wilmington-area residents concerned about the impacts of drinking the water install reverse osmosis systems.
Stapleton began studying filtration technology after testing the water at her Cary home and being alarmed at the amount of PFAS present. She installed a reverse osmosis system soon after, paying $300 for installation and between $80 and $100 a year to maintain the filter. Those costs are concerning to the Duke professor, who says they raise concerns about environmental justice, or how people who are able to afford filters will be able to protect themselves while those who can’t will be exposed to their potential effects.
“From my perspective, we should be focusing on where it’s coming from and stopping discharge of these chemicals in the first place because consumers shouldn’t be paying for this,” Stapleton said.
This reporting is financially supported by Report for America/GroundTruth Project and The North Carolina Local News Lab Fund, a component fund of the North Carolina Community Foundation. The News & Observer maintains full editorial control of the work. To support the future of this reporting, subscribe or donate.
This story was originally published February 5, 2020 at 5:28 PM.