01-27285. EPA Science Advisory Board Environmental Health Committee Review of the Trichloroethylene (TCE) Health Risk Assessment Synthesis and Characterization Draft Document; Request for Nominations

ACTION:

Request for nominations to the Environmental Health Committee (EHC) of the Environmental Protection Agency's (EPA) Science Advisory Board (SAB) for its review of the Agency's draft Trichloroethylene (TCE) Health Risk Assessment.

SUMMARY:

The U.S. Environmental Protection Agency Science Advisory Board (SAB) is announcing the formation of a Panel to review the Agency's draft Trichloroethylene (TCE) Health Risk Assessment. The SAB is soliciting nominations to augment the existing EHC to form this Panel. The EPA Science Advisory Board was established to provide independent scientific and technical advice, consultation, and recommendations to the EPA Administrator on the technical bases for EPA regulations. In this sense, the Board functions as a technical peer review panel.

Any interested person or organization may nominate qualified individuals for membership on the panel. Individuals should have expertise in one or more of the following areas: risk assessment and the application of the Agency's risk assessment guidelines; toxicology including carcinogenicity, with a focus on mechanisms of action and pharmacokinetic models; and molecular genetics. Nominees should be identified by name, occupation, position, address and telephone number. To be considered, all nominations must include a current resume providing the nominee's background, experience and qualifications.

Background

EPA's Office of Research and Development (ORD) has completed an external review draft assessing the health risks of trichloroethylene. TCE is a major contaminant of concern in EPA's air, water, and waste programs. This draft was published for public comment on September 19, 2001 at 66 FR 48257-48258. EPA's regulatory program and regional offices have identified TCE as among the highest priorities for a new assessment.

This assessment was also shaped by several new developments in risk assessment. The practice of risk assessment is evolving from a focus on one toxic effect of one pollutant in one environmental medium toward integrated assessments covering multiple effects and multiple media and incorporating information about mode of action, uncertainty, human variation, and cumulative effects of multiple pollutants in different media. This evolution responds to recommendations of the National Research Council, which have been embraced in EPA's proposed cancer guidelines.

This draft assessment takes on the new directions in risk assessment that EPA and others have advocated. The assessment discusses the possibility that children, infants, and the developing fetus may differ from adults with respect to susceptibility to TCE's toxic effects. The assessment addresses cumulative risks by discussing the implications of other chlorinated solvents and agents that have metabolic pathways, potential modes of action, and toxic effects similar to TCE. The assessment implements principles of the proposed cancer guidelines by emphasizing characterization discussions, using mode-of-action information, and identifying susceptible populations.

The issues surrounding TCE are quite complex, with extensive information in some areas and relatively little information in others. The ORD initiated development of 16 peer-reviewed state-of-the-science papers that were published in Environmental Health Perspectives (vol. 108, suppl. 2, May 2000). These papers, which provide the primary scientific support for the assessment, were written by well-recognized scientists carrying out research on TCE or its metabolites.

To accomplish this review, the Science Advisory Board (SAB) will convene a Panel to address the following draft Charge:

(a) Does the assessment adequately discuss the likelihood that trichloroethylene (TCE) acts through multiple metabolites and multiple modes of action?

(b) Is the cancer weight-of-evidence characterization adequately supported?

(c) A new feature of the cancer database is molecular information on the von Hippel-Lindau tumor suppressor gene. Is this information adequately discussed and are the conclusions appropriate?

(d) Does the assessment adequately discuss the use of multiple critical effects in developing an oral reference dose (RfD) and inhalation reference concentration (RfC) for effects other than cancer? Are the uncertainty factors well discussed and well supported?

(e) Does the assessment adequately discuss the derivation of a range of estimates for the cancer risk? Are there any studies that should/should not have been included?

(f) Please comment on the use of calibrated models and uncertainty analysis to address the question of pharmacokinetic model uncertainty.

(g) Is it appropriate to consider background exposures and other characteristics of an exposed population as modulating the risk of TCE exposure in that population?

(h) Do the data support identifying risk factors that may be associated with increased risks from TCE exposure? Are there any risk factors that should/should not have been included?

(i) Do the data support the possibility that TCE can affect children and adults differently? Should this be reflected in the quantitative assessment?

The criteria for selecting Panel members are that these persons be recognized experts in their fields; that they be as impartial and objective as possible; that they represent an array of backgrounds and perspectives (within their disciplines); and that they be available to participate fully in the review, which will be conducted over a relatively short time frame (i.e., within approximately four months). Panel members will be asked to attend at least one public meeting followed by at least one public telephone conference meeting over the course of four months; they will be asked to participate in the discussion of key issues and assumptions at these meetings, and they will be asked to review and to help finalize the products and outputs of the panel. The panel will make recommendations to the Executive Committee (EC) of the SAB for approval of the Board's report and transmittal to the Administrator.

Nominations should be submitted to Mr. Samuel Rondberg, Designated Federal Officer, EPA Science Advisory Board via e-mail to [e-mail] followed by “hard copy” via U.S. mail addressed to Mr. Samuel Rondberg, Designated Federal Officer, EPA Science Advisory Board (1400A), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington, DC 20460, telephone [phone], no later than November 9, 2001. The Agency will not formally acknowledge or respond to nominations.

General Information

Additional information concerning the EPA Science Advisory Board, its structure, function, and composition, may be found on the SAB Web site (http://www.epa.gov/​sab) and in the Science Advisory Board FY2000 Annual Staff Report which is available from the SAB Publications Staff at [phone] or via fax at [phone].

Dated: October 22, 2001.

Donald G. Barnes,

Staff Director, Science Advisory Board.