California regulators are proposing a tightening of what would be the first U.S. standard for hexavalent chromium in drinking water.
The draft standard of 0.02 parts per billion for the cancer-causing metal is more stringent than the original proposal, 0.06 ppb, from the state's Office of Environmental Health Hazard Assessment in 2009 (Greenwire, Aug. 21, 2009).
The move comes ahead of U.S. EPA's plans to update its standard, which limits a combination of chromium-6 and the chemical's nonhazardous trivalent form to 100 ppb but does not require separate screening for the highly toxic valence alone (E&ENews PM, Dec. 22, 2010).
California officials said they updated the draft standard in response to a peer review by University of California scientists.
"When finalized, the public health goal will give California a solid scientific basis for a health-protective drinking water standard for chromium 6," OEHHA Director Joan Denton said. "We expect the goal will be the first in the nation for this contaminant."
California EPA's Office of Environmental Health Hazard Assessment will make the proposal an official public health goal after a 30-day public comment period. The state Department of Public Health must then create an enforceable standard to replace the current standard of 50 ppb for chromiums 6 and 3 combined.
In 25 of 35 U.S. cities where tap water supplies were tested for hexavalent chromium, levels of the chemical exceeded the 0.06 ppb level, according to a report released last month by the Environmental Working Group (Greenwire, Dec. 20, 2010). Thirty-one cities would exceed the new level.
The chemical gained notoriety in California when residents of Hinkley sued utility Pacific Gas & Electric Co. for dumping hexavalent chromium from its natural gas compressor plant into waste ponds over a period of decades. The suit inspired the movie "Erin Brockovich."
However, a state cancer registry survey last month showed Hinkley residents did not have elevated rates of cancer (Greenwire, Dec. 13, 2010).
Click here to read the draft standard.
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