Trichloroethylene (TCE) Health Risk Assessment: Overview

ORDs National Center for Environmental Assessment is preparing a human health risk assessment on trichloroethylene (TCE). TCE is a solvent that has been widely used for vapor degreasing of metal parts, as an ingredient in adhesives, paint removers, correction fluid and spot removers, and as an extractant and chemical intermediate. Subsequent to its release, EPA's 2001 draft health risk assessment of TCE underwent a peer review by a panel of independent scientists through EPA's Science Advisory Board (SAB), which provided a peer review report in December 2002. In addition, the public submitted more than 800 pages of comments to EPA during a 120-day public comment period. In February 2004, EPA held a public symposium on new TCE science in which a number of authors of recently published scientific research presented their findings. Due to continuing science issues as well as emerging significant new science, further revision and external review have been planned. EPA, along with the Department of Defense, Department of Energy, and the National Aeronautics and Space Administration, is cosponsoring a consultation on TCE science issues with an expert panel convened by the National Academy of Sciences (NAS) Board on Environmental Studies and Toxicology. EPA has developed four issue papers that highlight important scientific issues related to TCE. These papers were provided to the NAS on February 15, 2005. The NAS panel first met on March 23-24, 2005 in Washington DC. The White House Office of Science and Technology Policy as well as EPA made presentations to the panel at that time.

Background:

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.

History/Chronology:

• August 2001: External review draft Trichloroethylene Health Risk Assessment: Synthesis and Characterization released.
• December 2002: EPA Science Advisory Board independent peer review report Review of Draft Trichloroethylene Health Risk Assessment: Synthesis and Characterization: An EPA Science Advisory Board Report (PDF, 83 pp, 376 KB, about PDF) published.
• February 2004: Symposium on New Scientific Research Related to the Health Effects of Trichloroethylene held in Washington, DC.
• September 2004: National Academy of Science consultation Trichloroethylene Health Risks: Key Scientific Issues initiated under sponsorship of EPA and other federal agencies.
• February 2005: EPA submitted four issue papers on key scientific issues to the NAS.
• March 2005: NAS expert panel met in Washington DC.

Next Steps:

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.

Related Links:

Public Comments on 2001 TCE Health Risk Assessment External Review Draft

Review of Draft Trichloroethylene Health Risk Assessment: Synthesis and Characterization: An EPA Science Advisory Board Report (PDF, 83 pp, 376 KB, about PDF)

NAS TCE project page

Citation