‘Forever chemicals’ found in tap water
Multiple Houston sites tested by scientists had ‘very high levels’ of a variety of PFAS
Some Houston tap water contains toxic “forever chemicals,” including many contaminants that fall outside federal testing guidance and newly proposed limits, while similar substances are found in at least 45 percent of U.S. drinking water, recent research studies show.
A peer-reviewed study by Natural Resources Defense Council scientists published this spring found high levels of a variety of synthetic chemicals known as PFAS in some Houston-area
tap water samples. Federal research by the U.S. Geological Survey then suggested that PFAS are present in at least 45 percent of tap water in the U.S., sparking concern over prevalence in private wells and public systems.
PFAS, short for perfluoroalkyl and polyfluoroalkyl substances, are used to make everything from nonstick cookware to firefighting foam. They are called “forever chemicals” because they break down very slowly or not at all under natural conditions.
Past research has shown that PFAS can already be found in the bodies of nearly all people living in the United States, and higher concentrations have a cumulative effect. Some of these toxic substances have been studied in-depth and found to cause liver damage, increase cancer risk and link to a range of other ailments. In preliminary research, others appear to sicken people in similar ways.
The EPA has asked water systems to monitor 29 “forever chemicals” but has never regulated them. In March, federal officials proposed the country’s first enforceable limits for six. But the new regulations would
not outlaw the combination of chemicals found in the Houston tap water samples.
Multiple Houston sites tested by NRDC had “very high levels” — over 40 parts per trillion — of a variety of PFAS, said researcher Katherine E. Pelch, though the combination would not exceed new proposed federal caps. Many of the 70 her team tested for are not commonly monitored by municipalities.
Some data that does exist, both on “forever chemicals” and other contaminants, is available in municipalities’ annual water quality reports and has been compiled by nonprofits like the Environmental Working Group. The national organization created a searchable online database to help residents filter the contaminants in their area.
How they get into water
Perfluoroalkyl and polyfluoroalkyl substances have been produced for industrial and household applications since the 1940s. They began prompting national concern about two decades ago when lawyer Robert Bilott secured internal documents from producers DuPont and 3M that showed the companies had long known their chemicals posed a public health risk.
An academic analysis of these previously secret documents was published earlier this year. Researchers showed companies had known the PFAS they created and used were “highly toxic when inhaled and moderately toxic when ingested” by 1970.
Many companies now have plans to phase out the use of the better-known “forever chemicals” once a cornerstone of synthetic products, replacing them with alternative PFAS that they say are less dangerous. But agencies including the Food and Drug Administration have called those claims into question.
Jackie Medcalf, executive director at Texas Health & Environment Alliance, which collaborated on data collection for the recent NRDC research, said Houston’s own tap water system is hard to analyze from limited sampling. It is not all governed by Houston Public Works, and even where it is, tap water feeds in from multiple sources: a mix of groundwater and surface water, of which only a small portion comes from Lake Houston.
“Our surface water has historically, and still to this day, received varying amounts of discharge into the waterways that contain PFAS,” Medcalf said. “Then there’s so much groundwater contamination in this region that that source creates a whole host of concerns.”
Another local group, Bayou City Waterkeeper, helped with the Houston-based testing for research last year that found PFAS in over 80 percent of 114 waterways across the country. The group’s sampling of White Oak Bayou, in northwest Houston, found elevated levels at two sites downstream of wastewater treatment plants.
Erin Jones, a spokeswoman for Houston Public Works, said that in the tap water it manages, the department does look for the 29 perfluoroalkyl and polyfluoroalkyl substances the EPA tests for.
“These … have not been listed in the current and previous Annual Water Quality Reports because none of these contaminants have been detected at or above the (EPA’s) maximum residue limits,” Jones said.
Those limits do not consider the cumulative impacts of several “forever chemicals” combined.
What the new rules say
The EPA’s March proposal for enforceable limits represents a big change for the federal agency. If adopted, municipalities would have to do more than report cancer-linked substances: They would have to filter PFAS out of the water or change their supply.
The federal agency’s plan is to cap two specific, well-known “forever chemicals,” PFOA and PFOS, at 4 parts per trillion each in public water systems. Research indicates these levels are still dangerous to drink, but they are dramatically lower than the EPA’s pre-2022 advisories. The agency also suggested a limit on the combined presence of four other variants: PFNA, PFHXs, PFBS, and GenX.
Medcalf, of the Texas Health & Environment Alliance, worries regulators’ step in the right direction could give Houstonians a false sense of security.
“We’d think, oh great, they’re looking for PFAS in our water now. (But) it actually looks for so few PFAS types in a very large chemical family,” she said.
Thousands of similar PFAS have been identified, and hundreds are thought to be used currently in manufacturing and industrial processes. While the two public water systems in the Houston area found to have elevated “forever chemicals” during researchers’ testing contained over 40 parts per trillion of the compounds in total, they did not surpass the proposed 4 parts per trillion threshold for either PFOA or PFOS, or the combined limit factoring in the four other variants.
Researchers in the Houston study tested water systems in 16 states for 70 PFAS substances, including 41 that are not currently covered by the EPA’s methods.
Specific sampling locations with elevated PFAS levels were not disclosed in the research paper, though its authors said two of three Houston testing sites had very high combined levels of the chemicals tested.
While the U.S. Geological Survey researchers did not test any Houston tap water, scientists working on that study looked at a huge number of samples, observing 716 locations across the country to understand the national picture.
Scientists looked at a range of “low, medium and high human impacted areas,” said Kelly Smalling, a research hydrologist on the project. They tested for 32 perfluoroalkyl and polyfluoroalkyl substances.
Scientists in the national study estimate that at least half of all U.S. tap water was contaminated, and concentrations are similar in public supplies and private wells. But they “cannot extrapolate” from their data how much of the Texas water supply is affected, Smalling said.
Researchers also concluded that the probability of drinking tap water free of the “forever chemicals” they measured was only 25 percent in urban areas, meaning the other three-quarters was likely contaminated.