State environmental regulators Thursday published safety guidelines for a toxic ingredient of rocket fuel called perchlorate, positioning California as the first state in the nation to regulate the pollutant that has infiltrated some drinking water supplies.
Laboratory studies have shown that perchlorate can affect the thyroid gland's production of hormones critical to early childhood development. The guidelines were mandated by state law and required to be published this week by court order.
The state's Office of Environmental Health Hazard Assessment made the determination of what would be a safe level. The guideline sets a dose of 6 parts per billion as the upper limit for safe human ingestion.
Dr. Joan Denton, director of the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment, cautioned that the public health goal -- which some criticize as too high and others as too low -- is not a final regulation setting maximum acceptable levels for the contaminant.
"This goal provides scientific guidance to health authorities in setting a regulatory standard for perchlorate in drinking water," Denton said. The regulation setting maximum acceptable contaminant levels will be completed within a year by the state Department of Health Services.
State officials said they might revise the guideline of 6 parts per billion -- the equivalent of 6 drops of water in a typical swimming pool -- depending on the outcome of an ongoing evaluation of the health effects of perchlorate by the National Academy of Sciences.
Perchlorate is an ingredient of rocket fuel, fireworks, road flares, air-bag inflation systems and other explosives. It has been found in a number of drinking water supplies, including the lower Colorado River, which supplies water to more than 15 million people in the Southwest, including Southern California.
The chemical has been detected in groundwater in Los Angeles and Ventura counties near the Rocketdyne Santa Susana Field Laboratory, and in wells near San Jose and Sacramento and in the San Gabriel Valley and the Inland Empire.
Sen. Dianne Feinstein (D-Calif.) applauded the state's action Tuesday, and scolded the Department of Defense for not stepping in to help clean up drinking water supplies contaminated by defense-related institutions.
"The scope of the contamination is enormous," Feinstein said. "It has been reported that perchlorate has now entered the food chain and is turning up ... in produce and dairy products. This is why it is so important the state move aggressively to stem the problem."