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Contaminants In Pittsburgh's Drinking Water Worry D.C. Environmental Group, But Not Local Experts

Occurence of Trihalomethanes in the Nation's Ground Water and Drinking Water Supply Wells, 1985-2002
United States Geological Survey
Pittsburgh is not alone in its notable concentration of trihalomethanes in public drinking water, but current assessments for what constitutes a "safe" level are based on nearly 20-year-old research.

Lead isn't the only potential water contaminant Pittsburgh residents should worry about, according to researchers at the nonprofit Environmental Working Group.

The Washington, D.C.-based research and lobbying group this week launched a website that allows residents to look up which contaminants are present in the local drinking water supply, at what levels they exist and how those levels compare with state and national averages.

In Allegheny County, the most common contaminants are byproducts of the disinfection process, particularly a class of chemicals called trihalomethanes.

“It would be very nice if we could have zero trihalomethanes in water, but we need to keep the drinking water safe from bacterial contamination, so we add disinfectants to our drinking water so it is safe,” said Leonard Casson, professor of environmental and civil engineering at the University of Pittsburgh.

All of the county’s major water authorities – Pittsburgh Water and Sewer Authority, Pennsylvania American Water, Wilkinsburg Penn Joint Water Authority, West View Water Authority and Hampton Shaler Water Authority – have trihalomethane levels below the legal limit of 80 parts per billion set by the federal Environmental Protection Agency.

But David Andrews, senior scientist with EWG, said the legal limit was set in 1998 and doesn’t necessarily reflect the latest research into health risks associated with trihalomethanes. Consumer-grade water pitchers and other systems already filter for trihalomethanes.

“The legal limit is really a negotiation between a health-based limit and economic and political considerations,” Andrews said.

He pointed to studies from France, Spain and Taiwan that linked trihalomethanes with bladder cancer in concentrations as low as 21 parts per billion. All five Pittsburgh-area water authorities have levels above that, ranging from 34.5 ppb at West View to 57.9 ppb at Penn American.

Aaron Barchowsky, professor of environmental and occupational health at Pitt, said he’s not convinced that trihalomethanes cause cancer.

“It’s a weak association that comes from rodent studies but … linking to human cancers has been controversial or weak at best,” Barchowsky said.

Andrews said researchers often have to study communities of hundreds of thousands of people to see an impact. He also raised a red flag about levels of hexavalent chromium, or chromium-6, in local water supplies, ranging from 0.0588 ppb in Wilkinsburg to 0.796 ppb at PWSA.

Hexavalent chromium is probably best known as the chemical against which activist Erin Brockovich crusaded in the 1990s. Andrews said the EPA does not have a legal limit for this particular type of chromium, only total chromium.

“It highlights the inability of the EPA to set or update new drinking water standards,” Andrews said, and that implementing a legal limit for the chemical under the Trump administration would be “a long shot.”

Barchowsky said he did not believe the levels of chromium found locally pose a risk to human health, and that those amounts of chromium-6 would be neutralized by the time they got past the tongue of someone drinking the water.

“The water is fairly safe, other than the lead issues,” Barchowsky said.

Liz Reid began working at WESA in 2013 as a general assignment reporter and weekend host. Since then, she’s worked as the Morning Edition producer, health & science reporter and as an editor.