This report describes case studies of source reduction process changes undertaken in four Massachusetts firms in order to reduce hazards associated with exposure to methylene chloride. Source reduction strategies aim to intervene in the industrial process itself to eliminate or reduce hazards through the use of chemical substitution, process modification, and/or substitute technologies. While common in environmental protection, source reduction strategies have not had broad acceptance in the industrial hygiene field and industrial hygienists have relied upon local exhaust ventilation and other control strategies that specifically do not change industrial processes. Such "interference" in industrial processes may have been deemed "infeasible," thus this study sought to report on the feasibility and effectiveness of source reduction strategies for the purposes of prevention of worker health hazards. The four firms profiled here had used methylene chloride, a high-volume chlorinated aliphatic hydrocarbon solvent, suspect occupational carcinogen and hazardous air pollutant, for cleaning and adhesive thinning operations. Three of the firms, a rubber products maker, an electrical equipment manufacturer, and an industrial vessel cleaning service, had eliminated use of methylene chloride at the time of the study. The fourth, a metal finishing company, was assisted by the investigator in reducing methylene chloride use. The case studies document the industrial process prior to and after the source reduction process, the steps each company took to accomplish the change, the company's motivations for the change, how the company evaluated the project, assessments of worker exposures before and after the change, costs, benefits and problems resulting from the change, and key lessons from each case. Data for the cases were collected via in-depth interviews, site visits including industrial hygiene walk-throughs, and document review. The key findings of this study include that 1) companies will undertake source reduction as a preferred strategy for regulatory compliance; 2) technical performance is companies' principal evaluation criterion; 3) source reduction efforts, while motivated by environmental and occupational health concerns, often have the benefit of improving production processes and saving companies money; 4) because exposure to methylene chloride is a significant worker health hazard, the elimination and reduction of its use resulted in improvement in the work environment. However, company review of the potential health and safety and environmental impact of "un-listed" or chemical supplier-recommended alternatives was limited and some new hazards, including ergonomic and noise, were introduced. Recommendations of this report include a new focus on technical assistance that can help companies identify optimal source reduction strategies and anticipate and minimize new occupational and environmental health and safety hazards is necessary to maximize the benefits of this approach.
Department of Work Environment, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854