Environmental Health News
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There are concerning carcinogens in Western Pennsylvania water

A national report finds cancer-causing chemicals in Pittsburgh's drinking water, including a disinfection byproduct at levels 3 times the national average

Some contaminants in Pittsburgh's drinking water—including disinfectant byproducts and industrial chemicals—are at unsafe levels and could contribute to the region's higher than average cancer rates, according to a new report.

A just-updated national tap water database tracks contaminants detected in drinking water throughout the country, and compares their levels against legal limits, safe limits, and state and national averages.

The database, published by the Environmental Working Group (EWG), a public health advocacy nonprofit, compiles all contaminant testing data conducted by nearly every water utility in the country through 2017, and provides details about the levels of pollutants detected and what health risks are associated with them.

The information provided in the database goes beyond what customers get in their annual reports from their water utilities, and reveals that a number of cancer-causing contaminants are being detected in drinking water throughout the U.S. EWG experts warn contaminated drinking water—most of which currently meets legal quality standards—could cause an estimated 100,000 cancer cases in the U.S.

The new database also reveals that several cancer-causing contaminants are found at levels significantly higher than national and state averages in Pittsburgh's drinking water.

For example, Bromodichloromethane is one of several trihalomethanes that can form when chlorine is added to water as a disinfectant and it combines with organic compounds. The chemical, which is categorized as a "probable human carcinogen" by the Environmental Protection Agency, was detected in water from the Pittsburgh Water and Sewer Authority (PWSA) at 16.8 ppb (parts per billion). That's nearly three times higher than the national average of 5.7 ppb, and double the state average of 8.34 ppb.

This level is also 280 times above EWG's Health Guideline of 0.06 ppb, which was derived from the California Office of Environmental Health Hazard Assessment in 2018. The number represents the level at which one in a million people exposed to that level over their lifetime will get cancer as a result. One in a million is generally considered an "acceptable" level of risk by the EPA when it comes to environmental exposures. Any level higher than that would lead to a greater number of people than one in a million getting cancer as a result of exposure to the chemical.

There is no legal limit for Bromodichloromethane in drinking water.

PWSA told EHN that the level of Bromodichloromethane cited in the EWG database was reported in 2016, and that more recent testing has shown reduced levels of the chemical. In 2018, the most recent full year available, they reported 14.3 ppb of Bromodichloromethane, and their year-to-date level for the first three quarters of 2019 is 13.9 ppb.

"While the levels of disinfection byproducts, including bromodichloromethane and other trihalomethanes in PWSA's drinking water are fully compliant with all applicable federal and state standards, we are aware of the concerns about these compounds raised in the EWG analysis, and are proactively taking steps to further reduce these levels," Robert A. Weimar, Executive Director of PWSA, told EHN.

Weimar added that upgrades currently underway planned in consultation with the Pennsylvania Department of Environmental Protection will allow PWSA to use activated carbon filtration, which will improve its ability to lower levels of disinfection byproducts, and that they're working with the American Water Works Association's Partnership for Safe Water to explore additional strategies to improve Pittsburgh's water quality.

Hexavalent chromium, which is commonly found in dye, paint, wood preservatives, and chrome plating waste, was also detected in PWSA's water. At 0.535 ppb, the contaminant is consumed by Pittsburghers at a rate 27 times higher than EWG's Health Guideline of 0.02 ppb. That level slightly exceeds the national average of 0.492 ppb, and is more than double the state average of 0.227 ppb. For the broader U.S., most of the cancer risk from water contaminants is due to arsenic and disinfection byproducts. Other major contaminants included radioactive elements such as uranium and radium.

"It's important for people to realize that legal doesn't necessarily mean safe," Sydney Evans, a Science Analyst at EWG, told EHN. "People tend to take the safety of their tap water for granted because it's being monitored, tested, and treated. But there's a big discrepancy between what's legal and what science says is safe."

Many drinking water limits for harmful contaminants haven't been updated in 20 to 40 years, Evans explained, and when those limits were set, regulators took into account not only the health effects of contaminants, but also the cost of removing them from drinking water and limitations of available technology, most of which has changed dramatically in recent decades.

"And beyond that," Evans added, "a lot of them don't even have legal limits yet. For example, hexavalent chromium, which is a potent carcinogen, has no federal legal limit in drinking water."

Regional problem

PWSA isn't the only water authority in the region with problems.

The following chemicals—all known, probable or possible carcinogens—were found in at least one of the 10 largest municipal drinking water systems in Allegheny County (which encompasses Pittsburgh):

  • Bromodichloromethane
  • Bromoform
  • Chloroform
  • Hexavalent chromium
  • Dibromochloromethane
  • Nitrate
  • Dichloroacetic acid
  • Trichloroacetic acid
  • Total trihalomethanes

These types of contaminants can get into drinking water in a number of ways. Some are the result of pollution from industries or municipal waste, but most occur when chemicals used to disinfect drinking water combine with organic compounds like those found in algae, agricultural runoff, or wastewater from the oil and gas industry.

Many carcinogenic contaminants were detected at levels significantly above national or state averages in the Pittsburgh region. A few examples:

  • Dibromochloromethane, another byproduct of chlorine disinfection, was detected at levels nearly four times the national and state averages at Moon Township Municipal Authority

Fossil fuel connection

A spokesperson for Pennsylvania American Water stated, "We take water quality and safety very seriously. The Environmental Protection Agency (EPA) sets water quality standards intended to protect public health and Pennsylvania American Water treats and delivers water that meets or surpasses all EPA and Pennsylvania drinking water standards."

Myron Arnowitt, Pennsylvania state director for the national environmental advocacy group Clean Water Action, said many of the carcinogens in Pittsburgh's drinking water come are the result of all the fossil fuel extraction in the region.

"Much of the research on this has found that brominated disinfection byproducts are the most dangerous of this group of carcinogens, and those are a number of the ones we have considerably higher levels of here than in other places," he told EHN.

"We don't add bromide," Arnowitt explained, "so the bromide is coming from the source water. There are several different sources, but certainly oil and gas wastewater has been a prominent one in Southwestern Pennsylvania. It's incredibly salty. Most of it is chloride, but a portion is bromide, and that portion is leading to higher levels of brominated disinfection byproducts for all the water systems in our region."

Arnowitt added that research suggests suggests coal plants may also be adding brominated materials to source water, and that as a region, we're taking on additional cancer risk as a result of being home to these fossil fuel industries. He also noted that these particular compounds are a difficult problem to treat at home.

"These contaminants are not something you can solve with a pitcher filter," he said. "These compounds are volatile, so the primary exposure around your house actually comes from breathing in steam from your shower."

Both Arnowitt and Evans at EWG emphasized the importance of protecting source water from these types of contaminants.

"The burden falls on treatment plants to get these contaminants out of the water, but they're not the ones putting them there in the first place," Evans said. "This is why regulations are so important—it costs a lot less to prevent the pollution in the first place than it does to try and clean it up down the line."

Cumulative exposures

Allegheny County is also in the top 2 percent of all U.S. counties for cancer risk from air pollution. All these exposures add up.

"When legal limits were being set for most of these contaminants in drinking water 20 or 40 years ago, they were looked at in isolation instead of in the mixtures we're all exposed to," Evans explained. "But that was just for those 22 contaminants, and just for drinking water," she added.

"When you start looking at all the different ways we're exposed, they're all going to make a difference." She also noted that some studies suggest exposure to a variety of carcinogens not only adds up, but the contaminants can also combine to become even more potent than they are in isolation.

A chart detailing which types of filters can remove each of the contaminants from drinking water is included in the page for each utility. The database also includes information on how residents can talk to their elected officials about the safety of their water.

"Ultimately, we want to see the process of reviewing these regulations streamlined, since it's currently inefficient, slow, and not health protective," Evans said. "To get there, we need to get people engaged on this issue in their communities."

More News

On February 12, 1958, Frank Capra's Unchained Goddess aired nationwide on CBS, warning viewers about rising CO2 in the atmosphere.

Before Gore, Greta, and the Green New Deal: Part One

What do the Three Stooges, Godzilla, Frank Capra and a 1960's Los Angeles Garage band have in common? They all snuck a bit of environmental storytelling into their art.


On February 13, 1958, three early pioneers in environmental communication brought one of the first mentions of "smog" to the big screen.

The Three Stooges had been in business since the 1920's. They hit the big time in the 1930's, with a lineup of Larry Fine, Moe Howard, and Moe's little brother, Curly. When Curly was incapacitated by a stroke in 1947, they repurposed Moe's oldest brother, Shemp, to continue the act. Shemp died in 1955, and the Stooges retrofit a particularly unfunny TV comic, Joe Besser, to replace him.

Using about 95 percent recycled joke content and short film plots, the act persevered. One of their last shorts, "Quiz Whizz," released to theaters, had a plot loosely based on Joe's investment in a Los Angeles business called "Consolidated Smog." As a public service, here's a link to the entire fifteen minute film. But feel free to click ahead to 2:30 for the first smog reference, since IMHO, none of this is particularly funny.

Godzilla vs. the Smog Monster 

With the possible exception of James Bond, no movie star has captured the global box office better than Godzilla. From the beginning, he (or she – there's debate about Godzilla's gender) had a strong anti-nuclear side, waking up from eons of slumber to curb-stomp Tokyo after nuclear weapons tests aroused him/her.

By 1971, Godzilla became Tokyo's savior rather than its stomper. Japan's meteoric postwar recovery had created massive industrial pollution, and an environmental movement similar to America's sprang up.

Enter Hedorah, a literal slimeball who grows bigger and stronger by ingesting pollution, belching the toxics back out as a defense against environmentalists. Godzilla Versus the Smog Monster teamed up the G-Man (or G-Woman) with a band of hippies whose dress and manner were over the top even for the LSD-soaked era.

I won't give away the ending, but this was Godzilla's eleventh feature, and (s)he has made 24 more since.

Doctor Research 

And I love this one. Frank Capra is the Hollywood legend who directed, wrote and produced some of cinema's most enduring feel-good flicks like Mr. Smith Goes to Washington and It's a Wonderful Life. In the 1950's, Capra honchoed a series of science shorts, sponsored by Bell Labs.

On February 12, 1958 – a day before the Stooges' smog gags played in theaters — Capra's Unchained Goddess aired nationwide on CBS. A central-casting scientist, Doctor Research (not his real name), warned about rising CO2 in the atmosphere:

"Even now, man may be unwittingly changing the world's climate through the waste products of his civilization. Due to our release through factories and automobiles every year of more than six billion tons of carbon dioxide, which helps air absorb heat from the sun, our atmosphere seems to be getting warmer. …. a few degrees rise in the Earth's temperature would melt the polar ice caps."

There is no record that Dr. Research, who was ably portrayed by UCLA English prof Frank Baxter, was accused of making it all up for the grant money back in '58. Or the residuals. But since then, our global CO2 output has increased by more than a factor of six.

Dirty Water 

Then there's a college-age garage band from Los Angeles. The Standells made Boston's "Dirty Water" famous without staining their carbon footprint by actually ever travelling to Boston.

The 1966 song didn't chart highly, but it remains an anthem for Boston and its sports teams, even as the Charles River has substantially cleaned up.

Next week, we'll visit some of the unlikely environmentalists in politics.

Peter Dykstra is our weekend editor and columnist. His views do not represent those of Environmental Health News, The Daily Climate or publisher, Environmental Health Sciences. He can be reached at pdykstra@ehn.org.