WASHINGTON, DC, April 12, 2007 (ENS) – The U.S. Environmental Protection Agency has decided to investigate the impacts of two water contaminants ”“ perchlorate and MTBE ”“ on human health.

Most of the perchlorate manufactured in the United States is used as the primary ingredient of solid rocket propellant. Wastes from the manufacture and improper disposal of perchlorate-containing chemicals are increasingly being discovered in soil and water.

MTBE is a fuel oxygenate, added to gasoline to make it burn more cleanly. Releases of MTBE to ground and surface water can occur through leaking underground storage tanks and pipelines, spills, emissions from marine engines into lakes and reservoirs.

For those two contaminants, the EPA is providing a summary of current health, occurrence, and exposure information. The agency is seeking comment and additional information from the public to determine if regulation of these chemicals in drinking water would reduce risks to human health.

At the same time, the agency today announced its “preliminary determination” not to regulate 11 contaminants on the second drinking water contaminant candidate list, CCL.

The Safe Drinking Water Act requires that the agency issue a CCL every five years for at least five contaminants from the most recent CCL. In 2005, the agency published the second CCL of 51 contaminants.

Based on a review of health effects and occurrence data, the EPA concluded that 11 specific contaminants do not occur at levels of public health concern in public water systems.

The 11 contaminants include naturally occurring substances, pesticides, herbicides and chemicals used in manufacturing now or in the past. They are:

    * Boron – a naturally occurring metal-like element used in industrial production

    * Dacthal mono- and

    * Di-acid degradates ”“ herbicides that should not be directly applied or discharged to surface waters

    * 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE) ”“ a degradate of the pesticide DDT, which was banned in 1973

    * 1,3-dichloropropene (Telone) ”“ a soil fumigant used to control nematodes which has labeling requirements to protect sources of drinking water

    * 2,4-dinitrotoluene, and

    * 2,6-dinitrotoluene ”“ chemicals found in ammunition, explosives, dyes, polyurethane foams and automobile air bags

    * s-ethyl propyl thiocarbamate (EPTC) ”“ an herbicide used on various food crops

    * Fonofos ”“ a soil insecticide which was discontinued by the manufacturer in 1999

    * Terbacil ”“ an herbicide used to control broadleaf weeds

    * 1,1,2,2-tetrachloroethane ”“ a volatile organic chemical once used for a variety of industrial uses

While none of the contaminants were found nationally at levels of public health concern, EPA is recommending that health advisories for seven of the contaminants be updated to provide local officials with current health information for situations where the contaminants may occur.

Learn more about the contaminant candidate list: http://epa.gov/safewater/ccl/reg_determine2.html

EPA will take comments for 60 days following publication of a notice in the Federal Register.