The EPA recently released a revised draft risk assessment of ammonium perchlorate, a component of solid rocket fuel. The EPA recommended limiting perchlorate in drinking water to nearly undetectable levels earlier this year, determining the contaminant is more harmful than previously thought. The recommendation calls for lowering the perchlorate level in drinking water from 32 parts per billion (ppb) to 1 ppb. For children, the level should be no higher than 0.3 ppb, compared with the standard of 10 ppb set in 1998.

The draft risk estimate level is not a drinking water standard, but it is the first step in a lengthy process to determine if the agency should set a federal drinking water standard for this contaminant.

The efforts to characterize potential risks from perchlorate contamination and development of this revised external review draft have followed an open public process, highlighted by the working partnerhsip of the Interagency Perchlorate Steering Committee, which is co-chaired by the EPA and the U.S. Department of Defense, and which currently comprises representatives from more than 23 state, federal and tribal agencies.

After comments derived from the current public comment period are addressed, the final assessment document will undergo the agency's consensus clearance for inclusion on the EPA's Integrat-ed Risk Information System.

The draft assessment is available at the EPA's Internet site ( under "What's New."