Carcinogenic hexavalent chromium, the "Erin Brockovich chemical" was found in the tap water of 31 cities out of a total of 35 tested by The Environmental Working Group. The scientists estimate that at least 74 million people in the USA in 42 states regularly drink chromium-tainted water, and a considerable proportion of it is in the carcinogenic hexavalent form. Hexavalent chromium is recognized as a human carcinogen... 
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