Perchlorate Workshop

Background

The processes involved in standard setting are often difficult, requiring the weighing of health concerns against cost of treatment and availability of water. The contaminant, perchlorate raises many difficult issues that must be resolved in order to set an appropriate standard. The State Department of Health Services is poised to produce a drinking water maximum contaminant level (MCL) for perchlorate in June of 2004.

The Office of Environmental Health Hazard Assessment (OEHHA) has developed a risk assessment level for the compound. Monitoring for perchlorate has shown that many surface and groundwater supplies, upon which California is dependent, are contaminated. The action level for California is currently 4μ g/L (ppb) and rumors abound on the level at which the MCL could be set.

Perchlorate typifies a contaminant for which there is conflicting information on health effects and where the health effects goal has been set at 2-6 μ g/L. The high solubility of perchlorate aids its spread in groundwater and makes it difficult to remove by conventional technologies. Removal by ion exchange resins presents additional problems, because other constituents such arsenic or radon may also be accumulated, resulting in a spent resin that might be considered a hazardous waste.

The Urban Water Research Center convened a committee of experts in consultation with SDHS, OEHHA, environmental health scientists, toxicologists, engineers and economists to determine the nature and the effect of different standard levels on human health, California's water supplies, the types of treatment available, and the cost of compliance. The charge to the committee was to examine the information available on all aspects of the contaminant and determine what is in the best interests of the state, its people and its water supply. The Scholar's Committee on Perchlorate Review held three meetings from October 2003 through February 2004.

The final report, Perchlorate in Drinking Water: A Science and Policy Review, represents the committee's views regarding the perchlorate issue. The document includes the background information leading to their conclusions and recommendations. After a period of public comment and inclusion of those comments, the report, currently underway, was submitted to the State Department of Health Services in June, 2004 to help advance their important decision-making process.