EPA revises perchlorate evaluation

Suzanne Struglinski

Monday, Feb. 21, 2005 | 9:19 a.m.

WASHINGTON -- The Environmental Protection Agency on Friday declared that the amount of perchlorate that is safe is much greater than the agency had previously recommended.

The EPA says up to 24.5 parts of perchlorate per billion parts of water are safe for consumption. That matches what the National Academy of Sciences recommended last month, but it is higher than what the agency suggested earlier. The EPA had recommended a 1 part per billion protection standard two years ago.

The EPA's ruling will factor into guidelines for clean-ups of the chemical and will be used to determine whether the agency will regulate perchlorate in drinking water.

EPA spokeswoman Cynthia Bergman called the ruling, known as a reference dose, "a first step" for the agency as it begins to regulate perchlorate, a toxic chemical used in rocket fuel and explosives. If ingested in high doses, perchlorate can decrease the thyroid gland's functions, which can lead to health problems.

The chemical leaked into the Las Vegas Valley's water supply from two Henderson chemical plants, one owned by Kerr-McGee, a Defense Department contractor. Perchlorate was first detected in Lake Mead in 1997. Kerr McGee stopped making perchlorate in 1998 and a cleanup project began in 1999. The other plant, owned by American Pacific, moved to Utah in 1989.

J.C. Davis, spokesman for the Southern Nevada Water Authority, said the new EPA rule will not change anything for or impact the valley's water supply. He said the perchlorate levels in Lake Mead have dropped by about 85 percent.

"It should encourage people who live here that our standards are one-fifth of it," Davis said. "We don't have to do any better. Nevada was very proactive on this."

Davis said the authority will continue to try to remove as much as the chemical as possible from drinking water.

Before the EPA can set a drinking water limit for the chemical, Bergman said the agency needs to consider whether the source of people ingesting it comes from food or water. The chemical can get into water supplies, but it can also be in lettuce and milk, according to studies by the Food and Drug administration.

In the next month, Bergman said the agency is likely to issue new clean-up rules for contaminated sites using the new level. This is higher than the 4 parts per billion to 18 parts per billion recommended cleanup level the agency has now.