The U.S. Environmental Protection Agency has made a preliminary determination not to regulate 11 contaminants on the second drinking water contaminant candidate list. The agency's preliminary regulatory determination, based on a review of health effects and occurrence data, concludes that the specific contaminants do not occur at levels of public health concern in public water systems.

The U.S. Environmental Protection Agency (EPA) has made a preliminary determination not to regulate 11 contaminants on the second drinking water contaminant candidate list (CCL). The agency's "preliminary regulatory determination," based on an extensive review of health effects and occurrence data, concludes that the specific contaminants do not occur at levels of public health concern in public water systems.

Two other contaminants – perchlorate and MTBE – require additional investigation to ascertain total human exposure and health risks. For those contaminants, EPA is providing a summary of current health, occurrence and exposure information. The agency is seeking comment and additional information to help EPA's evaluations.

A regulatory determination is a formal decision on whether EPA should develop a national primary drinking water regulation for a specific contaminant. The Safe Drinking Water Act requires that EPA 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.

The 11 contaminants include naturally occurring substances, pesticides, herbicides and chemicals used (or once used) in manufacturing. EPA monitored eight of the contaminants during the first round of the unregulated contaminant monitoring program, and the remaining three during previous occurrence surveys. 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.

EPA will take comments for 60 days following publication of a notice in the Federal Register. The 11 contaminants 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 airbags
  
• 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

To learn more about the contaminant candidate list, visit epa.gov/safewater/ccl/reg_determine2.html