Perchlorate, a toxic ingredient of solid rocket fuel that is contaminating hundreds of wells throughout Southern California, would be limited in drinking water under a new state standard proposed Monday.
The California Department of Health Services plans to set a drinking water standard of 6 parts per billion, the same as a goal the state established two years ago. The standard, however, would be enforceable, whereas the existing goal is not.
The proposal allows the health department "to address a contaminant that, unfortunately, is quite common in certain areas of California," said state Public Health Officer Mark Horton. "Perchlorate's potential for harm is of concern to pregnant women and their developing fetuses, as well as children, so limiting exposure to this contaminant is important for protecting public health."
Most of the water contamination comes from military bases and aerospace plants, where perchlorate was widely used as the explosive component of solid rocket propellants.
The U.S. Environmental Protection Agency earlier this year set a much higher interim cleanup goal for perchlorate -- 24.5 parts per billion. But the federal agency has not yet set an enforceable standard for drinking water.
"The states are again acting in the face of inaction by federal EPA," said Bill Walker of the Environmental Working Group, an environmental health advocacy organization. "While we would have liked to have seen California's standard lower, and it could leave some Californians at risk, the big story is the difference between it and EPA's. This is another strong signal to EPA that its [goal] is much too high and that they need to stop the foot-dragging and move forward with a truly protective drinking water standard."
Massachusetts is the only state with a mandatory drinking water limit -- 2 parts per billion, which went into effect last month. Environmental groups had urged California to adopt a more stringent standard, from 1 to 2 parts per billion, but the Pentagon and its contractors objected that such a low standard would be unwarranted.
Taxpayers and industry "will face staggering costs to meet requirements that could be set by California" or the U.S. EPA, according to a report by a water quality group funded by Lockheed Martin, Aerojet and other companies linked to perchlorate contamination.
James Strock, who represents the aerospace industry group, the Council on Water Quality, said that California should have set a higher allowable level just as the EPA did, because it "ensures a clear margin of safety for the most sensitive subpopulations, including pregnant women, fetuses and newborns."
"At a time when California is urgently seeking all available resources to apply to a range of urgent environmental priorities ... this regulation appears to divert resources in a direction that will yield little if any additional public health protection," said Strock, who was secretary of the California Environmental Protection Agency under former Gov. Pete Wilson.
Walker said he was relieved that state health officials did not back down to pressure from industry. The state had the option of setting a less-stringent limit than the existing public health goal because officials are allowed under state law to factor in economic costs, not just health risks, when setting a final standard for drinking water.
Scientists say perchlorate interferes with iodine uptake by the thyroid gland, which can disrupt brain development in fetuses and young children.
Once the standard is adopted, water providers throughout California must monitor their supplies for the chemical and shut down any wells and other sources that exceed the limits.
More than 450 wells and other water sources operated by more than 100 water agencies in California -- primarily in Los Angeles, Orange, Riverside, San Bernardino and Sacramento counties -- have been contaminated by perchlorate, according to the state health department. One of the biggest tainted sources is the Colorado River, which supplies vast amounts of water to Southern California.
The chemical also has been widely found in milk, cheese, lettuce and other crops that are tainted by irrigation water, as well as human breast milk and baby formula.
Kerr-McGee Corp., which produced the chemical at a now-closed plant near Las Vegas, has already mounted a costly cleanup to pump groundwater and remove perchlorate that flows into the Colorado River. The river's perchlorate levels are now lower than California's proposed limit.
In 2005, a panel of the National Academy of Sciences reaffirmed the thyroid threat to pregnant women and gave the EPA a recommendation of a safe perchlorate dose. Based on that advice, the EPA came up with a guideline of 24.5 parts per billion. Some scientists, including some at the California health department, have questioned the panel's findings and suggested that the EPA was misconstruing the academy's advice.
Melanie Marty, of California's Office of Environmental Health Hazard Assessment, told the EPA in March that the federal agency needs to set a standard soon, and that it needs to be stringent to protect children.
The EPA's interim goal "is not supported by the underlying science and can result in exposures that pose neurodevelopmental risks in early life," she wrote as chairwoman of the EPA's Children's Health Protection Advisory Committee.
The state health agency will hold a hearing on its proposed regulation Oct. 30 in Sacramento. Comments from the public will be accepted until Nov. 3.