News Coverage
U.S. increases 'safe' standard for perchlorate
New rules will affect military base cleanup and may apply to drinking water.
Published February 19, 2005
Federal environmental regulators on Friday established a safe dose for perchlorate at more than 20 times the level they originally had calculated for the chemical, an ingredient of solid rocket fuel that has tainted drinking water and food supplies nationwide.
The Environmental Protection Agency's new limit will guide regulators in setting levels of cleanup at military installations and other sites where the chemical has seeped into groundwater.
The number also will be used in calculating the amount of perchlorate allowable in drinking water, should the federal agency go further and regulate the chemical as a drinking-water contaminant.
Large doses of the chemical, in widespread use by the military since the 1950s, have been shown to interfere with the thyroid gland, which plays a major role in children's brain development.
The EPA safety standard matches the dose recommended last month by an expert panel with the National Academy of Sciences.
Several environmental groups said Friday that the EPA limit fails to protect infants and fetuses but makes it easier for the Defense Department and its contractors to oppose stricter cleanup rules.
"Are they going to protect children or are they going to protect polluters?" asked Richard Wiles, senior vice president of Environmental Working Group, which along with the Natural Resources Defense Council has engaged its own set of scientists to assess the health risks of the chemical.
But EPA officials said they incorporated a 10-fold uncertainty margin in the safety limit to protect babies and fetuses of pregnant women who might have hypothyroidism, or iodine deficiency.
After months of reviewing available scientific evidence, a 15-member panel of the academy concluded that humans could safely ingests levels up to 0.0007 milligrams per kilogram of body weight per day, which is more than 20 times the 0.00003 mg/kg daily dose that the EPA had proposed in January 2002.
The safety dose is a scientific estimate of a daily exposure level that is not expected to harm humans.
Perchlorate contamination has been found in at least 35 states, and more than 20 million people have some levels in their drinking water.
The Food and Drug Administration also recently found the chemical in milk and lettuce.
In California, perchlorate has leaked into aquifers from chemical factories and aerospace plants in at least 10 counties, most notably in Sacramento, Santa Clara, Los Angeles, Orange, Riverside and San Diego.
GenCorp's Aerojet in Rancho Cordova has spent millions of dollars in perchlorate monitoring and cleanup.
Linda Cutler, spokeswoman for GenCorp, said the EPA decision will not affect its decontamination operation.
The company intends to continue cleaning up perchlorate-contaminated groundwater to 4 parts per billion, substantially less than the EPA's new safety standard.