NCPA - National Center for Policy Analysis

No Risk in U.S. Drinking Water

February 4, 2011

Environmental Working Group (EWG) claims to have found harmful levels of hexavalent chromium (chromium-6) in the drinking water of 35 U.S. cities, and it is calling for swift federal regulatory actions.  The group timed their study to coincide with the Environmental Protection Agency's (EPA) routine review of its drinking water standard for chromium -- but the EPA review doesn't support EWG's claims.  The evidence of significant risk from chromium in U.S. drinking water is weak, says the Competitive Enterprise Institute.

  • It is true that some studies have linked chromium-6 to lung cancer among workers who inhaled high levels of chromium-6 over a relatively long time period, but those studies are not very relevant to ingestion of trace levels in drinking water.
  • Still, EWG says the chemical is dangerous because it has produced tumors in rodents.
  • But those studies, which were conducted by the National Toxicology Program in 2007 and 2009, involved rodents that ingested relatively high levels -- between 5,000 to 180,000 parts per billion -- of the chemical in drinking water over two years, a long time frame in the life of a rat.

These very high, long-term exposures of rodents to chromium tell us little about impacts on humans who are periodically exposed to levels that are thousands of times lower.  For example, the amounts of chromium-6 that EWG found in U.S. drinking water averaged at just 0.18 parts per billion, with the highest rate of 12.9 parts per billion in Norman, Oklahoma, says the Competitive Enterprise Institute.

The EWG scare campaign has gained many headlines in part because of chromium-6's notoriety from the film, Erin Brockovich.  If EPA imposes an onerous chromium-6 standard because of activist pressures, public health benefits are likely to be zero.  The compliance costs could be high, particularly for relatively poor, rural communities that have few resources to waste, says the Competitive Enterprise Institute.

Source:  Angela Logomasini, "Politicized Science: The 'Erin Brockovich Chemical'," Competitive Enterprise Institute, February 1, 2010.

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