Trichloroethylene (TCE) Health Risk Assessment Overview

TCE, a chlorinated solvent, was widely used for metal degreasing and is now a common contaminant at hazard waste sites and many federal facilities. TCE has been identified in at least 1500 hazardous waste sites regulated under Superfund or the Resource Conservation and Recovery Act. Besides being used for degreasing, TCE has been used as an extractant and as a chemical intermediate. Most of the TCE used in the United States is released into the atmosphere from vapor degreasing operations. TCE can enter surface waters via direct discharges and groundwater through leaching from disposal operations and Superfund sites; the maximum contaminant level for TCE in drinking water is 5 ppb. TCE can be released to indoor air from use of consumer products that contain it, vapor intrusion through underground walls and floors and volatilization from the water supply.

The next meetings of the NAS expert panel are scheduled for April 20-21, 2005 in Washington DC and June 9-10, 2005 in Irvine, California. A report from the NAS is expected in 2006. EPA will incorporate the advice from the NAS, along with comments from the EPA Science Advisory Board and the public, as well as recently published scientific literature, into a revised TCE health risk assessment. This revised assessment will then undergo both external peer review and public comment prior to being completed.