Warning that babies are especially vulnerable, a federal panel of scientists has lambasted the Environmental Protection Agency's health goal for a toxic chemical that has widely contaminated drinking water and foods, particularly in Southern California.
The EPA's new goal for perchlorate, an ingredient of solid rocket fuel, "is not supported by the underlying science and can result in exposures that pose neurodevelopmental risks in early life," wrote Melanie Marty of California's Office of Environmental Health Hazard Assessment, who chairs the EPA's Children's Health Protection Advisory Committee.
The letter from the committee of 26 scientists, sent to EPA Administrator Stephen L. Johnson on March 8, warned the agency that it is putting babies at unnecessary risk of neurological damage. The EPA's interim goal for perchlorate, announced in January, "does not protect infants and should be lowered," the scientists said in their letter.
It is the second time in less than two months that an EPA scientific advisory panel has criticized the Bush administration for proposing a standard or guideline for a pollutant that would not adequately protect public health.
Most perchlorate contamination comes from military bases and aerospace plants. In California, at least 350 water wells have been contaminated by perchlorate, largely in the Los Angeles Basin, according to the Department of Health Services, and it has also tainted supplies in about 40 other states.
There is no current enforceable national standard for perchlorate in drinking water. But six weeks ago, the EPA set an interim goal of 24.5 parts per billion. The idea was to guide cleanup of industrial and Pentagon waste sites and contaminated drinking water until the federal agency decides on a standard that drinking water must meet.
California recently proposed a much tighter goal of 6 ppb, and on Monday, Massachusetts proposed a standard of 2 ppb. California's goal, set by Marty's agency, is not enforceable because the state Department of Health Services has not yet set a drinking water standard.
In animal studies, perchlorate has been shown to disrupt thyroid hormones. Low thyroid hormone levels can obstruct the brain development of fetuses and young children, causing subtle reductions in their intelligence and other mental abilities.
EPA officials were unavailable Wednesday for comment on the letter.
The EPA has said its decision was based on a 2005 recommendation of a "safe" dose from a committee from the National Academy of Sciences.
Some scientists have questioned the findings of that committee, saying that the dose was set too high, and also suggested that the EPA is misconstruing some of its advice.
The scientists on the children's health panel said they were troubled that the EPA's goal assumes that exposure comes only from drinking water, not from food. Perchlorate has been widely found in milk, cheese, lettuce and other crops, which are tainted by irrigation water, as well as in human breast milk and baby formula.
Out of 33 samples of milk purchased in Los Angeles and Orange counties in 2004, perchlorate was found in all but one, according to tests by the Environmental Working Group, an environmental health advocacy group.
The scientists on the committee wrote that food tainted by perchlorate-contaminated irrigation water "is an obvious concern given the widespread detection of perchlorate in lettuce and milk."
They advised the EPA to set an enforceable standard for drinking water, and to pay special attention to protecting fetuses from perchlorate exposure in the womb and babies from contamination from breast milk or formula.
"Perchlorate is an important ... toxicant because of widespread exposure and the potential for impairment of the thyroid during critical stages of brain development," Marty wrote. "The risk posed by this environmental agent is preventable by appropriate agency action."
"It's time for the EPA to wake up and listen to what the states and its own advisors are saying: Perchlorate is a threat to children at very small doses," said Renee Sharp, an Environmental Working Group scientist who obtained the scientists' letter Tuesday. "The Bush administration has given no sign that it's going to set a national drinking water standard, and the EPA's recommendations leave children at risk."
The Environmental Working Group, which has advocated a perchlorate standard of 1 ppb or 2 ppb, , said that an average 1-year-old, weighing about 25 pounds, would exceed the EPA's safe dose for perchlorate after drinking just one cup of milk per day.
Perchlorate is widely used by the U.S. military and defense contractors as the explosive component of rocket propellants, and also is used in fireworks and other explosives. It has been found at 45 of the nation's 1,500 Superfund sites, which are the nation's worst hazardous waste sites, and the EPA's goal would affect the extent of cleanup there and at other sites.
Sources of the contaminant include the now-closed Kerr-McGee chemical plant near Las Vegas, which contaminated the Colorado River, which provides drinking and irrigation water in Southern California.
That contamination has been reduced by a company-sponsored cleanup.
In February, the EPA's clean-air scientific review committee challenged the agency's proposed health standards governing particulates, tiny pieces of soot that are considered the nation's deadliest air pollutant.
The scientists said the agency ignored most of their recommendations to curb particulates, which could lead to additional heart attacks and deaths from asthma and other respiratory ailments.