Collecting well water samples for testing.

The U.S. Environmental Protection Agency (EPA) has issued new protective guidance for cleaning up perchlorate contamination situations, recommending a preliminary clean-up goal for perchlorate of 24.5 parts per billion in water. EPA's guidance is derived from the agency's reference dose for perchlorate, which is based on the 2005 recommendations and conclusions of the National Academy of Sciences.

This preliminary goal is a starting point for an evaluation of site-specific conditions. Consistent with current practice, final clean-up determinations should take site-specific information into consideration. This latest action offers clear guidance to site managers to help ensure national consistency in evaluating perchlorate in light of widely varying state guidance. This decision was based on the best available science and will be updated as new information becomes available.

Perchlorate has been detected in ground water or drinking water at approximately 45 of the 1,500 sites on EPA's National Priorities List. Perchlorate salts were first produced in the United States in the mid-1940s, primarily for use by the military for explosives and rocket propellants. Perchlorate salts also have been used in other applications, including pyrotechnics and fireworks, blasting agents, matches, lubricating oils, air bags and certain types of fertilizers.