United States EPA Document# 740-R1-4003 Environmental Protection Agency August 2014 Office of Chemical Safety and Pollution Prevention TSCA Work Plan Chemical Risk Assessment Methylene Chloride: Paint Stripping Use CASRN: 75-09-2 H Cl H Cl August 2014 TABLE OF CONTENTS LIST OF TABLES .............................................................................................................................................................. 6 LIST OF FIGURES ............................................................................................................................................................ 10 AUTHORS/CONTRIBUTORS/ACKNOWLEDGEMENTS/REVIEWERS ................................................................................. 12 GLOSSARY OF TERMS AND ABBREVIATIONS ................................................................................................................. 14 EXECUTIVE SUMMARY .................................................................................................................................................. 19 1 BACKGROUND AND SCOPE .................................................................................................................................. 27 1.1 INTRODUCTION ........................................................................................................................................27 1.2 BACKGROUND ..........................................................................................................................................28 1.2.1 Rationale for Selecting DCM for Risk Assessment ....................................................................................28 1.2.2 Overview of DCM Uses and Production Volume ......................................................................................28 1.2.3 Overview of !ssessments of DCM’s Human Health Hazards ...................................................................28 1.2.4 Overview EP!’s Regulatory History of DCM .............................................................................................29 1.3 SCOPE OF THE ASSESSMENT.....................................................................................................................30 1.3.1 Selection of DCM Uses..............................................................................................................................30 1.3.2 Selection of Exposure Pathway ................................................................................................................30 1.3.3 Identification of Human Populations Exposed During the Use of DCM-Based Paint Strippers ................30 1.3.4 Why Environmental Risks Were Not Evaluated For DCM-Based Paint Strippers .....................................32 2 SOURCES AND FATE ............................................................................................................................................. 33 2.1 PHYSICAL AND CHEMICAL PROPERTIES ....................................................................................................33 2.2 DCM PRODUCTION AND USES ..................................................................................................................34 2.2.1 Market Trends and Uses ..........................................................................................................................34 2.2.1.1 Consumer Uses.......................................................................................................................................................... 37 2.2.1.2 Paint Stripping Applications ...................................................................................................................................... 38 2.3 SUMMARY OF ENVIRONMENTAL FATE ....................................................................................................38 3 HUMAN HEALTH RISK ASSESSMENT .................................................................................................................... 39 3.1 OCCUPATIONAL EXPOSURE ASSESSMENT FOR THE USE OF DCM IN PAINT STRIPPING ............................39 3.1.1 Approach and Methodology for Estimating Occupational Exposures ......................................................39 3.1.1.1 Identification of Relevant Industries ......................................................................................................................... 39 3.1.1.2 Estimation of Potential Workplace Exposures for Paint Stripping Facilities .............................................................. 40 3.1.1.3 Summary of Occupational DCM Exposure Estimates ................................................................................................ 46 3.1.1.4 Worker Exposure Limits for DCM .............................................................................................................................. 49 3.2 CONSUMER EXPOSURE ASSESSMENT FOR THE USE OF DCM IN PAINT STRIPPING ..................................50 3.2.1 Approach and Methodology for Estimating Consumer Exposures ...........................................................50 3.2.2 Overview of the MCCEM ..........................................................................................................................50 3.2.3 MCCEM Input Parameters and Assumptions ...........................................................................................52 3.2.3.1 Estimation of Emission Profiles for Paint Removers/Strippers .................................................................................. 52 3.2.3.2 Method of Application .............................................................................................................................................. 53 3.2.3.3 Amount Applied to the Surface (Product Mass) ........................................................................................................ 53 3.2.3.4 Stripping Sequence ................................................................................................................................................... 54 3.2.3.5 Amount of Chemical Released .................................................................................................................................. 55 3.2.3.6 Airflow Rates and Volumes ....................................................................................................................................... 55 3.2.3.7 Locations of Exposed Individuals ............................................................................................................................... 56 3.2.4 MCCEM Modeling Scenarios ....................................................................................................................56 3.2.4.1 Sensitivity Analysis .................................................................................................................................................... 57 3.2.4.2 Exposure Scenarios for the DCM Inhalation Exposure Assessment .......................................................................... 60 3.2.5 Consumer Model Results ..........................................................................................................................65 3.3 HAZARD/DOSE-RESPONSE ASSESSMENT .................................................................................................67 Page 2 of 279 3.3.1 Approach and Methodology ....................................................................................................................67 3.3.1.1 Selection of Peer-Reviewed Hazard/Dose-Response Assessments as the Source Documents for the DCM TSCA Assessment ............................................................................................................................................................... 67 3.3.1.2 Chronic Hazard and Dose-Response Assessment: EPA IRIS Toxicological Review of Methylene Chloride ................ 68 3.3.1.2.1 Carcinogenic Effects Following Chronic Exposure to DCM................................................................................ 68 3.3.1.2.2 Non-Cancer Effects Following Chronic Exposure to DCM ................................................................................. 69 3.3.1.3 Acute Hazard and Dose-Response Assessment ......................................................................................................... 72 3.3.1.3.1 SMACs ............................................................................................................................................................... 73 3.3.1.3.2 California’s !cute REL ....................................................................................................................................... 74 3.3.1.3.3 AEGLs ................................................................................................................................................................ 75 3.3.2 Human Health Hazard Summary .............................................................................................................78 3.3.2.1 Absorption, Distribution, Metabolism and Excretion ................................................................................................ 78 3.3.2.2 Human and Animal Toxicity Following Acute Exposure to DCM ............................................................................... 79 3.3.2.3 Human and Animal Toxicity Following Repeated Exposures to DCM ........................................................................ 80 3.3.2.3.1 Non-Cancer Effects 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