Source reduction for prevention of methylene chloride hazards: cases from four industrial sectors

BACKGROUND: Source reduction, defined as chemical, equipment and process changes that intervene in an industrial process to eliminate or reduce hazards, has not figured as a front-line strategy for the protection of workers' health. Such initiatives are popular for environmental protection, but their feasibility and effectiveness as an industrial hygiene approach have not been well described. METHODS: We investigated four cases of source reduction as a hazard prevention strategy in Massachusetts companies that had used methylene chloride, an occupational carcinogen, for cleaning and adhesive thinning. Three cases were retrospective and one was prospective, where the researchers assisted with the source reduction process change. Data were collected using qualitative research methods, including in-depth interviews and site visits. RESULTS: Motivated by environmental restrictions, a new worker health standard, and opportunity for productivity improvements, three companies eliminated their use of methylene chloride by utilizing available technologies and drop-in substitutes. Aided by technical assistance from the investigators, a fourth case dramatically reduced its use of methylene chloride via process and chemistry changes. While the companies' evaluations of potential work environment impacts of substitutes were not extensive, and in two cases new potential hazards were introduced, the overall impact of the source reduction strategy was deemed beneficial, both from a worker health and a production standpoint. CONCLUSION: The findings from these four cases suggest that source reduction should be considered potentially feasible and effective for reducing or eliminating the potential hazards of methylene chloride exposure. Especially when faced with a hazard that is both an environmental and worker health concern, companies may chose to change their processes rather than rely on local exhaust ventilation equipment or personal protective equipment that might not be as effective, might transfer risk and/or not be integrated with financial goals. However, technical assistance sensitive to environmental and health and safety impacts as well as production issues should be provided to guide companies' source reduction efforts

Hazard Rating of Substances Systems Developed by Niosh’s Rtecs-Nohs and Usepa

This research study attempts to evaluate the hazard rating of substances systems developed by NIOSH’s (National Institute for Occupational Safety and Health) RTECS-NOHS (Registry of Toxic Effects of Chemical Substances – National Occupational Hazards Survey) and USEPA (United States Environmental Protection Agency). Evaluation on rating methodologies and parameters used by both NIOSH and USEPA’s systems reviewed that both systems aim at ranking common industrial organic compounds used or released into the atmosphere with special focus on chemical toxicological health effects. The NIOSH’s RTECS-NOHS system solely emphasizes on health risks depending on chemical toxicological effects pertaining to eight health effect endpoints, whilst USEPA’s system considers toxicological effects, occupational standards, chemical production rate, fraction of production loss and chemical’s volatility characteristics. It is also found that NIOSH’s system allows users great flexibility in defining toxicological priorities by assigning a multiplier or/and adding in the constants. The scoring system developed by USEPA for the individual parameters considered in the priority ranking range from zero to five without providing flexibility for users in defining toxicological priorities or assigning multipliers. It is also found that certain modifications must be made to account for fundamental differences between worker and population exposures for application purposes

The difficulties in establishing an occupational exposure limit for carbon nanotubes

Concern over the health effects from the inhalation of carbon nanotubes (CNTs) has been building for some time, and adverse health effects found in animal studies include acute and chronic respiratory damage, cardiac inflammation, and cancer including mesothelioma, heretofore only associated with asbestos exposure. The strong animal evidence of toxicity requires that the occupational hygiene community develops strategies for reducing or eliminating worker exposures to CNTs; part of this strategy involves the setting of occupational exposure limits (OELs) for CNTs. A number of government agencies and private entities have established OELs for CNTs; some are mass-based, while others rely on number concentration. We review these various proposed standards and discuss the pros and cons of each approach. We recommend that specific action be taken, including intensified outreach to employers and employees concerning the potential adverse health effects from CNT inhalation, the development of more nuanced OELs that reflect the complex nature of CNT exposure, a broader discussion of these issues among all interested parties, and further research into important unanswered questions including optimum methods to evaluate CNT exposures. We conclude that current animal toxicity evidence suggests that strong action needs to be taken to minimize exposures to CNTs, and that any CNT OEL should be consistent with the need to minimize exposures