Trace amounts of an industrial chemical and suspected carcinogen are hanging out in much of the nation's drinking water supply, per a report published Wednesday by the Environmental Working Group, an advocacy organization. The report suggests that the chemical often shows up in quantities that could be dangerous to long-term health—yet the current administration appears unlikely to take any action, experts worry.
The chemical in question is known as 1,4-dioxane, a clear liquid solvent regularly used since the 1950s in the manufacturing of plastics and other chemicals as well as a contaminant found in many cosmetic and household products. Though 1,4-dioxane has been classified as a likely carcinogen by the Environmental Protection Agency (EPA) and other regulatory agencies for decades, it's only in recent years that health officials have tried to measure how much of it the average person is exposed to via drinking water. The current report is among the first to quantify exposure levels on a national scale. And the results are sobering.
"There's widespread contamination all across the United States," Tasha Stoiber, one of the report's authors and a senior scientist with the EWG, tells Tonic . "And you can see there are a lot of hot spots where levels exceed [the EPA's exposure level of negligible cancer risk in drinking water, 0.35 parts per billion]."
Looking at EPA-mandated samples taken from more than 50,000 public water systems throughout every state from 2010 to 2015, the authors found that at least 90 million Americans get their water from sources where 1,4-dioxane is routinely detected. Of these, more than 7 million people in 27 states are potentially drinking water where the average level of 1,4-dioxane is higher than the safest level of exposure established by the EPA in 2013. In water systems with the worst levels of contamination, such as the one that serves the entire east Los Angeles area, people are exposed to more than 10 times that amount. California—where 1,4-dioxane is listed as a chemical known to cause cancer—has the most people exposed to these higher levels of the substance, at 2.5 million residents, followed by North Carolina with 1.2 million and New York with 700,000.
Here's a map of the EWG's findings:
1,4-dioxane, which often finds its way into our water supply through runoff from factories or toxic waste that seeps into the ground, is associated with serious health effects like liver and kidney damage in workers exposed to high levels for a short time. The dangers of long-term exposure, specifically cancer risk, have been harder to pinpoint, though, since scientists have only been able to rely on animal studies for evidence. In lab mice and rats, ingested 1,4-dioxane has been shown to cause tumors in the liver, nose, breast, and abdomen.
The EPA's safety benchmark of 0.35 ppb is considered to be the amount of 1,4-dioxane that would cause no more than one extra case of cancer in one million people who drink and bathe with contaminated water over a lifetime. That amount of the chemical is about one drop of water in three Olympic-size swimming pools, the EWG says.
Separate from drinking water, it's harder still to figure out how much of a cancer risk 1,4-dioxane-contaminated products like shampoo, lotion, foaming soaps, and household cleaners pose, especially since levels can drastically vary from one product to the next. Stoiber says the risk is likely lower than from drinking water, though. A 2012 EWG analysis found that 22 percent of personal care products may contain the chemical.
While 1,4-dioxane is currently unregulated by the EPA, the chemical has been singled out as a potential threat since 2013, when it was placed on the agency's third iteration of its drinking water contaminant candidate list (CCL). Chemicals on the CLL, which has been updated every five years since 1998, are tracked and evaluated by the EPA in order to determine whether they require regulation. Last year, the EWG report notes, 1,4-dioxane was included alongside asbestos as one of the first ten chemicals to be reviewed under the Chemical Safety for the 21st Century Act, which strengthened safety standards for new and existing chemicals the public is exposed to through all potential routes including manufacturing, water contamination, personal use, disposal, and spills.
But Stoiber says the Trump administration likely isn't taking 1,4-dioxane anywhere near as seriously as it should. The planned review of 1,4-dioxane, for example, won't take into account any exposure from consumer products, according to risk evaluation documents released earlier this June—seemingly in violation of the new chemical safety law.
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President Trump's nominee to head the EPA's chemicals and pesticides office, Michael Dourson, is also the head of a consulting firm that has regularly argued against chemical regulations, TERA. Dourson himself released two review papers, in 2014 and 2017, which downplayed the cancer risk of 1,4-dioxane and argued people can safely be exposed to 1,000 times the EPA's benchmark, 350 ppb.
"These studies were funded by industry and didn't consider the full weight of toxicology evidence," Stoiber argues, referring to an assessment of Dourson's research by the Michigan Departments of Environmental Quality and Community Health in 2015. "For instance, he only looked at a few studies in rats, but not mice."
Adding insult to injury, EPA staffing levels could soon hit a 30-year low. The Wall Street Journal reports that almost 400 workers have left the agency in recent days, many as the result of buyouts as the Trump administration fulfills campaign promises of "tremendous cutting" at the EPA.
As pessimistic as Stoiber is about Trump's EPA doing anything substantial to curtail 1,4-dioxane levels in drinking water and consumer products, she says there are proactive steps others can take. State health and environmental agencies can set their own stricter limits, as some already have, as well as invest in newer filtering technology that can remove dioxane from the water supply. Manufacturing companies can better prevent ground and surface water contamination by changing their disposal practices. In New York, which has seen high levels of 1,4-dioxane contamination in the Long Island area recently, Senators Chuck Schumer and Kirsten Gillibrand petitioned the Food and Drug Administration to formally ban 1,4-dioxane from personal care products, another approach the EWG endorses.
"It's really easy to avoid this chemical by not using cosmetics contaminated with it," she adds, noting the EWG maintains a database of more than 70,000 personal care products that users can navigate to find safer products (the FDA doesn't require it to be listed on product labels). "You can easily eliminate the risk from that path of exposure at least."
Unfortunately, for people living in 1,4-dioxane hotspots right this moment, there's no easy solution. "It's really difficult to treat it at home. There's not really an effective home water filter you can use, at least not one that's 100 percent effective," Stoiber says. "So we recommend contacting your utility and local officials and voicing your concern by pushing for groundwater clean-up or freshwater protection."
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