Chromium in the Water

Just before the Christmas holidays—December 20, 2010, to be exact—Environmental Working Group (EWG) released a report that many home faucets are supplying drinking water that’s laced with the cancer-causing metal chromium-6, otherwise known as hexavalent chromium. In fact, of the tap water EWG sampled from 35 American cities, 31 contained chromium-6, and water samples from 25 of those cities had chromium-6 at concentrations above the safe maximum set by California regulators. The highest levels were found in Norman, Oklahoma; Honolulu, Hawaii and Riverside, California. In that Oklahoma city, chromium-6 levels were at a shocking 12.9 parts per billion (ppb); the recommended safe level being considered by California is .06 ppb.

Chromium-6 is used for chrome plating, dyes, pigments, leather tanning and wood preserving. During the course of manufacture and disposal, it ends up in the soil and groundwater. And it’s everywhere. The Agency for Toxic Substances & Disease Registry (ATSDR) reports that chromium “has been found in at least 1,127 of the 1,669 National Priorities List sites identified by the Environmental Protection Agency (EPA).” It’s specifically in the chromium-6 form, however, that the chemical is carcinogenic. ATSDR writes that inhaling the toxic metal causes lung cancer in both workers and animals; and that humans and animals exposed to chromium-6 have increased stomach tumors. The metal has also led to developmental defects in animals. By EWG’s estimate, some 74 million Americans are drinking tap water laced with the stuff at some levels.

On Dec. 22, the EPA responded to the unsettling report by releasing a statement that “The agency regularly re-evaluates drinking water standards and, based on new science on chromium-6, had already begun a rigorous and comprehensive review of its health effects. In September, we released a draft of that scientific review for public comment. When this human health assessment is finalized in 2011, EPA will carefully review the conclusions and consider all relevant information, including the Environmental Working Group’s study, to determine if a new standard needs to be set.”

SOURCES: Agency for Toxic Substances & Disease Registry; Environmental Working Group; U.S. Environmental Protection Agency.