An environmental group that analyzed the drinking water in 35 cities across the United States, including Madison, WI, found that most contained hexavalent chromium (a.k.a. chromium-6), a probable carcinogen that was made famous by the film "Erin Brockovich." Of the 35 cities’ drinking water that was tested, Madison ranks number four worst at 1.58 ppb.
The study, released today by the Environmental Working Group (EWG), is the first nationwide analysis of hexavalent chromium in drinking water to be made public. Although no safety limits have been set nationwide for the chemical, the state of California has proposed “a public health goal” for safe levels of 0.06 ppb.
According to the Washington Post, this comes as the Environmental Protection Agency (EPA) is considering whether to set a limit for hexavalent chromium in tap water. The agency is reviewing the chemical after the National Toxicology Program, part of the National Institutes of Health, deemed it a "probable carcinogen" in 2008.
Hexavalent chromium has long been known to cause lung cancer when inhaled, but scientists only recently found evidence that it causes cancer in laboratory animals when ingested. It has been linked in animals to liver and kidney damage as well as leukemia, stomach cancer and other cancers.
Hexavalent chromium was a commonly used industrial chemical until the early 1990s. It is still used in some industries, such as in chrome plating and the manufacturing of plastics and dyes. Hexavalent chromium gets into water supplies after being discharged from steel and pulp mills as well as metal-plating and leather-tanning facilities. The chemical can also leach into groundwater from natural ores.
The EWG study states that while the EPA has set a legal limit in tap water for total chromium of 100 ppb to protect against “allergic dermatitis” (skin irritation or reactions), these measures include the essential mineral trivalent chromium, which regulates glucose metabolism, as well as the cancer-causing hexavalent form.
Preliminary EWG-commissioned water tests, however, found that in most cases, the majority of the total chromium in water was in the hexavalent form. The EPA’s legal limit for total chromium, furthermore, is 1,700 times higher than California's proposed public health goal for hexavalent chromium. This disparity could indicate significant cancer risk for communities drinking chromium-tainted tap water, including Madison.
Max Costa, who chairs the department of environmental medicine at New York University's School of Medicine and is an expert in hexavalent chromium, called the new findings "disturbing."
"At this point, we should strive to not have any hexavalent chromium in drinking water" or at least limit the amounts to the level proposed by California, Costa wrote in an e-mail to the Washington Post.
Ken Cook, president of the EWG, provided a realistic assessment of the situation to the Post, explaining why water utilities across the country are resistant to the regulation.
"It's not their fault. They didn't cause the contamination. But if a limit is set, it's going to be extraordinarily expensive for them to clean this up," Cook said. "The problem in all of this is that we lose sight of the water drinkers, of the people at the end of the tap. There is tremendous push-back from polluters and from water utilities. The real focus has to be on public health."
The study suggests that about 74 million U.S. residents from 42 states drink tap water with chromium, the bulk of which are likely in the cancer-causing form. Here are the cities cited in the EWG study, with the top 10 ppb levels of hexavalent chromium listed:
- Norman, OK - 12.90 ppb
- Honolulu, HI - 2.00
- Riverside, CA - 1.69
- Madison, WI - 1.58
- San Jose, CA - 1.34
- Tallahassee, FL - 1.25
- Omaha, NE - 1.07
- Albuquerque, NM - 1.04
- Pittsburg, PA - 0.88
- Bend, OR - 0.78
- Salt Lake City, UT
- Ann Arbor, MO
- Atlanta, GA
- Los Angeles, CA
- Bethesda, MD
- Phoenix, AZ
- Washington, DC
- Chicago, IL
- Milwaukee, WI - 0.18
- Villanova, PA
- Sacramento, CA
- Louisville, KY
- Syracuse, NY
- New Haven, CT
- Buffalo, NY
- Las Vegas, NV
- New York, NY
- Scottsdale, AZ
- Miami, FL
- Boston, MA
- Cincinnati, OH
- Indianapolis, IN
- Plano, TX
- Reno, NV
- San Antonio, TX
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