Abstract  In Canada, approximately 13.2 kilotonnes of dichloromethane are used annually, in such applications as paint removal, as a blowing agent in foam production, and as a component in aerosols. Due to its volatility and the dispersive nature of its uses, the majority of dichloromethane used may be released into the environment, primarily the atmosphere. Dichloromethane has been measured in indoor air, outdoor air, and surface waters across Canada. Based on these considerations, it has been concluded that dichloromethane occurs at concentrations that may be harmful to the environment, and that may constitute a danger in Canada to human life or health. It has been concluded that dichloromethane occurs at concentrations that do not constitute a danger to the environment on which human life depends. (Copyright (c) Minister of Supply and Services Canada 1993.)

Abstract  This document provides occurrence-related background information on 22 regulated drinking water contaminants in support of the Environmental Protection Agency’s (EPA’s) second Six-Year Review of National Primary Drinking Water Regulations (the “second Six-Year Review”). These 22 contaminants are referred to as “Category 1 contaminants” based on their: relatively high rates of occurrence at or near concentration thresholds of concern; new or ongoing health effects assessments; and potential new laboratory analytical capabilities. The 22 Category 1 contaminants are: benzene, carbofuran, carbon tetrachloride, chlordane, 1,2-dibromo­3-chloropropane, 1,2-dichloroethane, dichloromethane, 2,4-dichlorophenoxyacetic acid, 1,2­dichloropropane, endothall, heptachlor, heptachlor epoxide, hexachlorobenzene, hexachlorocyclopentadiene, oxamyl, tetrachloroethylene, toluene, toxaphene, 1,1,2­trichloroethane, trichloroethylene, vinyl chloride, and xylenes (total). This support document is divided into contaminant-specific chapters. The individual contaminant chapters include background information (regulatory history, general chemical information, and environmental fate and behavior), use and environmental release information, an overview of occurrence in ambient water, and national estimates of contaminant occurrence in public drinking water systems. The national drinking water occurrence estimates presented here are based on the data contained in the National Compliance Monitoring Information Collection Request Dataset for the Second Six-Year Review (the “Six Year Review-ICR Dataset”), which includes data collected from 1998 to 2005. This is the largest and most comprehensive drinking water contaminant dataset ever compiled by EPA’s Drinking Water Program and includes 15 million records for 69 regulated contaminants submitted by 47 states/primacy agencies (45 states plus Region 8 and Region 9 tribes). Using this dataset, a variety of occurrence estimates were generated to characterize the national occurrence of regulated contaminants in public water systems (PWSs).