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OPPT Proposed Draft Charge to External Peer Reviewers for the review of 

the TSCA Workplan Chemical Risk Assessment of DCM

December, 2012

This assessment focused on the use of DCM in paint stripping. There are human health concerns 

for both cancer and non-cancer effects with DCM use-application. This assessment of DCM 

paint stripping uses focused only on inhalation exposure to workers, consumers, and bystanders. 

General question on the risk assessment

Issue 1. General Question on the Risk Assessment of DCM. The document describes the 

scope for the DCM human health risk assessment (Chapter 1); provides information on 

chemistry, environmental fate and transport, production, and uses (Chapter 2); and characterizes 

exposure, hazard, and risk (Chapter 3). Supporting information is provided in appendices. The 

risk assessment is intended to provide a clear and transparent summary of EPA’s analysis.

Question 1-1: Please comment on whether the assessment provides a clear and logical

summary of EPA’s analysis. Please provide specific suggestions for improving the 

document. 

Question 1-2: Please comment on whether appropriate background information is provided 

and accurately characterized. Please provide any other significant literature, reports, or data 

that would be useful to complete this assessment.

Questions on the exposure assessment of DCM

Issue 2. EPA found limited published data for DCM air concentrations in workplace 

settings during use of DCM-based paint strippers. These data were used for estimating 

occupational inhalation exposures.

Question 2-1: What other sources of data are available to estimate inhalation occupational 

exposures. Please provide specific citations.

Question 2-2: Please specify other data that could be used to estimate occupational dermal 

exposures during use of DCM-based paint strippers. Please specify sources of these data. 

Issue 3. Inhalation exposures for consumer uses of DCM in paint stripping were estimated 

using the EPA’s Multi-Chamber Concentrations and Exposure Model (MCCEM). EPA 

conducted a sensitivity analysis of model parameters to identify critical parameters 

essential to the modeling approach used to estimate inhalation exposures. This analysis 

guided the selection of exposure scenarios and provided the most sensitive input 

parameters for generating upper end concentrations.
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Question 3-1: Please comment on the strengths and weaknesses of model evaluation of

different exposure scenarios. 

Question 3-2: Please comment on the choice of assumptions/input parameters for generating 

upper end concentrations and provide specific suggestions for improving this approach. 

Please specify other sources of these data.

Questions for the assessment of human health and risks of DCM

Issue 4. EPA used information from the Cal EPA reference exposure level to develop an 

acute exposure hazard for inhalation uses of DCM in paint stripping. This was based upon 

deficits in cognitive and sensory performance in humans following short term acute 

exposures to DCM. In addition, for comparison, EPA also included information on 

endpoints from acute exposure guideline levels (AEGLs) to illustrate “context exposureresponse levels for endpoints across a range of adversity”. 

Question 4-1: Please comment on the assumptions and the strengths and weakness of this 

approach to provide “context exposure-response levels for endpoints across a range of 

adversity”. Provide feedback on other critical endpoints that could be considered further 

enhance the characterization of the hazard of acute inhalation exposures. Please provide data 

or documentation and rationale for including other studies and endpoints to be considered. 

Issue 5. The Chronic non-cancer risks were assessed using liver damage in rats as the 

Point of Departure (POD).

Question 5-1: What other critical endpoints could be considered to further enhance the 

characterization of the hazard of chronic inhalation exposures for DCM-paint stripping 

applications? Please provide data or documentation and rationale for including other studies 

and endpoints for consideration.