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Trichloroethylene Health Risk Assessment

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Information about this document as published in the Federal Register.

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Environmental Protection Agency.


Notice of Availability and Public Comment Period.


The U.S. Environmental Protection Agency (EPA) announces the availability of a report titled, “Trichloroethylene Health Risk Assessment: Synthesis and Characterization,” External Review Draft, (EPA/600/P-01/002A). The draft assessment was prepared by EPA's National Center for Environmental Assessment (NCEA), a part of the Office of Research and Development. This report is a draft for review purposes only and does not constitute Agency policy.

EPA is also announcing a 60-day public comment period on the draft assessment.

EPA's Science Advisory Board (SAB) will convene an external peer-review panel to review the draft assessment in the Fall. The SAB will publish a subsequent Federal Register notice to announce the time and place of the peer-review meeting, including information on how the public can participate. After the peer-review meeting, NCEA will address the panel's comments and the public's comments and issue a final assessment. At that time, a summary of the final assessment will be included on EPA's Integrated Risk Information System (IRIS).


Comments should be in writing and must be postmarked by November 19, 2001.


The draft assessment will be available on the Internet at​ncea. A limited number of paper copies are available from NCEA's Technical Information Staff, telephone: 202-564-3261; facsimile: Start Printed Page 48258202-565-0050. If you request a paper copy, please provide your name, mailing address, and the report title, Trichloroethylene Health Risk Assessment.

Comments may be mailed to NCEA's Technical Information Staff at the mailroom address: Technical Information Staff (8623-D), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue NW., Washington, DC 20460. Comments may also be delivered to the NCEA's Technical Information Staff at the office address: 808 17th Street NW., 5th Floor, Washington, DC 20006; telephone: 202-564-3261; facsimile: 202-565-0050. Electronic comments may be e-mailed to:

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Dr. Jim Cogliano, National Center for Environmental Assessment, telephone: 202-564-3288; facsimile: 202-565-0079; e-mail:

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This assessment presents EPA's most current evaluation of the potential health risks from exposure to trichloroethylene (TCE). TCE exposure is associated with several adverse health effects, including neurotoxicity, immunotoxicity, developmental toxicity, liver toxicity, kidney toxicity, endocrine effects, and several forms of cancer. Mechanistic research indicates that TCE-induced carcinogenesis is complex, involving multiple carcinogenic metabolites acting through multiple modes of action. Under EPA's proposed (1996, 1999) cancer guidelines, TCE can be characterized as “highly likely to produce cancer in humans.”

For effects other than cancer, an oral reference dose (RfD) of 3×10−4 mg/kg-d was based on critical effects in the liver, kidney, and developing fetus. An inhalation reference concentration (RfC) of 4×10−2 mg/m\3\ was based on critical effects in the central nervous system, liver, and endocrine system. Several cancer slope factors were developed, with most between 2×10−2 and 4×10−1 per mg/kg-d. Several sources of uncertainty have been identified and quantified.

The mechanistic information suggests some risk factors that may make some populations more sensitive. There are suggestions that TCE could affect children and adults differently. In addition, several chemicals have the potential to alter TCE's metabolism and clearance and subsequent toxicity, conversely, TCE exposure can augment the toxicity of other chemicals. Widespread environmental exposure to some of TCE's metabolites makes it important to consider the cumulative effect of TCE along with other environmental contaminants.

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Dated: August 31, 2001.

Art Payne,

Acting Director, National Center for Environmental Assessment.

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[FR Doc. 01-23310 Filed 9-18-01; 8:45 am]