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Hexavalent Chromium Widespread in US City Drinking Water Supply


The Environmental Working Group has tested tap water from 35 American cities and found that 89 percent contain a cancer-causing chemical highlighted in the 2000 movie “Erin Brockovich.” Water samples from 25 cities contained concentrations that exceed safety maximums proposed by regulators in California.

89% of Cities Had Chromium-6 Levels Higher than California Safety Standards

The EWG, a Washington-based research and advocacy organization, estimates that at least 74 million Americans in 42 states drink tap water polluted with hexavalent chromium, also known as chromium-6. The National Toxicology Program has concluded that the chemical shows “clear evidence of carcinogenic activity” in laboratory animals, increasing the risk of gastrointestinal tumors.

The Environmental Protection Agency (EPA) also reported in September 2010 that hexavalent chromium in tap water is “likely to be carcinogenic to humans” but has yet to require testing for the toxic metal. While there is no federal limit set for chromium-6, the EPA has set a limit on total chromium at 100 ppb to protect against “allergic dermatitis.”

Read: Arsenic Exposure in Drinking Water Increases Risk of Stroke

Hexavalent chromium gets into water supplies after being discharged from steel and pulp mills as well as metal-plating and leather-tanning facilities. It can also pollute water through erosion of soil and rock.

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To study the amount of hexavalent chromium present in the US drinking water supply, the EWG hired an independent laboratory to test water from 31 cities across the nation. The highest levels were detected in Norman, Oklahoma where the contamination was detected to be at 12.9 parts per billion (ppb), over 200 times the proposed safe limit of 0.06 ppb.

The remaining cities in the top five are Honolulu HI (2.0 ppb), Riverside CA (1.69 ppb), Madison WI (1.58 ppb) and San Jose CA (1.34 ppb). Among the major US cities surveyed, Chicago was found to have 0.18 ppb of chromium-6 in water supplied by Lake Michigan, Los Angeles had 0.20 ppb, Atlanta 0.18 ppb, and Boston 0.03 ppb.

Read: Ohio EPA Finds Algae Toxins in Public Drinking Water Supplies

Among the cities without detectable chromium-6 levels were Indianapolis IN, Plano TX, Reno NV, and San Antonio TX.

The Environmental Working Group states that the EPA should “move expeditiously to establish a legal limit for the chemical in tap water and require water utilities to test for it.”

Rebecca Sutton, senior scientist with the EWG suggests that until there are more regulations in place, consumers should buy an effective water filter to remove hexavalent chromium. While bottled water is often thought to be safer than tap water, Sutton warns that “we just don’t have any guarantee that hexavalent chromium isn’t in [bottled] water.”