Mesothelioma and employment in massachusetts: analysis of cancer registry data 1988-2003.

BACKGROUND: Cancer registries can be used to monitor mesothelioma cases and to identify occupations and industries previously and newly associated with mesothelioma-causing asbestos exposure by using standard registry data on the "usual" occupation and industry of the case. METHODS: We used the National Institute for Occupational Safety and Health's Standardized Occupational Industry Coding Software to code 564 mesothelioma cases for occupation and 543 for industry of the 1,424 incident mesothelioma in the Massachusetts Cancer Registry from 1988 to 2003. Additionally, we coded the occupation and industry of 80,184 comparison cancer cases (35% of comparison cases in our database). These were used to compute Standardized Morbidity Odds Ratios (SMORs). RESULTS: Seventeen occupations and 11 industries had statistically significant elevated SMORs for mesothelioma. Occupations and industries historically associated with mesothelioma remained elevated in these results. However, we also found statistically significant elevated SMORs for several occupations and industries for which there was previously weak or no association such as chemical engineers, machine operators, and automobile mechanics and machine manufacturing, railroads, and the U.S. Postal Service. CONCLUSIONS: Incident cases of mesothelioma do not appear to be declining in Massachusetts, as legacy exposures to asbestos continue to produce cases in individuals involved in shipbuilding and construction. Exposures in occupations and industries not previously associated with mesothelioma also contribute cases. Cancer registries, with improved data collection, should continue to be monitored for mesothelioma cases and asbestos exposures.

Epigenetic profiles distinguish pleural mesothelioma from normal pleura and predict lung asbestos burden and clinical outcome.

Mechanisms of action of nonmutagenic carcinogens such as asbestos remain poorly characterized. As pleural mesothelioma is known to have limited numbers of genetic mutations, we aimed to characterize the relationships among gene-locus-specific methylation alterations, disease status, asbestos burden, and survival in this rapidly fatal asbestos-associated tumor. Methylation of 1505 CpG loci associated with 803 cancer-related genes were studied in 158 pleural mesotheliomas and 18 normal pleura. After false-discovery rate correction, 969 CpG loci were independently associated with disease status (Q < 0.05). Classifying samples based on CpG methylation profile with a mixture model approach, methylation classes discriminated tumor from normal pleura (permutation P < 0.0001). In a random forests classification, the overall misclassification error rate was 3.4%, with <1% (n = 1) of tumors misclassified as normal (P < 0.0001). Among tumors, methylation class membership was significantly associated with lung tissue asbestos body burden (P < 0.03), and significantly predicted survival (likelihood ratio P < 0.01). Consistent with prior work, asbestos burden was associated with an increased risk of death (hazard ratio, 1.4; 95% confidence interval, 1.1-1.8). Our results have shown that methylation profiles powerfully differentiate diseased pleura from nontumor pleura and that asbestos burden and methylation profiles are independent predictors of mesothelioma patient survival. We have added to the growing body of evidence that cellular epigenetic dysregulation is a critical mode of action for asbestos in the induction of pleural mesothelioma. Importantly, these findings hold great promise for using epigenetic profiling in the diagnosis and prognosis of human cancers.

Asbestos burden predicts survival in pleural mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rapidly fatal asbestos-associated malignancy with a median survival time of <1 year following diagnosis. Treatment strategy is determined in part using known prognostic factors. OBJECTIVE: The aim of this study was to examine the relationship between asbestos exposure and survival outcome in MPM in an effort to advance the understanding of the contribution of asbestos exposure to MPM prognosis. METHODS: We studied incident cases of MPM patients enrolled through the International Mesothelioma Program at Brigham and Women's Hospital in Boston, Massachusetts, using survival follow-up, self-reported asbestos exposure (n=128), and a subset of cases (n=80) with quantitative asbestos fiber burden measures. RESULTS: Consistent with the established literature, we found independent, significant associations between male sex and reduced survival (p<0.04), as well as between nonepithelioid tumor histology and reduced survival (p<0.02). Although self-reported exposure to asbestos was not predictive of survival among our cases, stratifying quantitative asbestos fiber burden [number of asbestos bodies per gram of lung (wet weight)] into groups of low (0-99 asbestos bodies), moderate (100-1,099), and high fiber burden (>1,099), suggested a survival duration association among these groups (p=0.06). After adjusting for covariates in a Cox model, we found that patients with a low asbestos burden had a 3-fold elevated risk of death compared to patients with a moderate fiber burden [95% confidence interval (CI), 0.95-9.5; p=0.06], and patients with a high asbestos burden had a 4.8-fold elevated risk of death (95% CI, 1.5-15.0; p<0.01) versus those with moderate exposure. CONCLUSION: Our data suggest that patient survival is associated with asbestos fiber burden in MPM and is perhaps modified by susceptibility.

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.

Prevention strategies in industrial hygiene: a critical literature review.

Little is known of the extent of use of industrial hygiene prevention and control strategies in actual workplaces. The recent occupational safety and health literature was identified as a potential source for identifying which strategies are being utilized and evaluated as a means of controlling or preventing chemical hazards. Using preestablished selection criteria, the peer-reviewed industrial hygiene literature 1994-1999 was searched for articles describing prevention and control strategies for chemical hazards in actual workplaces. Ninety-two articles were found and categorized by the type of strategy discussed, whether strategies were implemented and evaluated, and by several other categories. Almost three-quarters discussed engineering control strategies, mostly local exhaust ventilation. Administrative strategies, including housekeeping, personal hygiene, and medical surveillance, appeared in about half the articles. Personal protective equipment was considered in one-third of the articles, and primary prevention strategies, such as material substitution, were considered in one-quarter. Intervention effectiveness was not consistently evaluated in these articles. In response to these findings, recommendations are made to improve the evaluation and promotion of effective prevention and control strategies.

Results of the Massachusetts methylene chloride end-users survey.

A survey of Massachusetts companies reporting use of methylene chloride between 1995 and 1999 was conducted to assess the status of industrial use of the chemical in 2000. Methylene chloride has had wide use in industry although it has been identified as potentially hazardous to exposed workers and the environment. New and tightened occupational and environmental regulations taking effect in the 1990s were hypothesized to have reduced use of the chemical in Massachusetts. Substitute technologies, especially aqueous cleaning, were expected to have replaced methylene chloride in many industries. Seventeen of the 21 Massachusetts manufacturing companies reporting use of over 10,000 lb/y of methylene chloride between 1995 and 1999 were surveyed by telephone regarding their experiences of methylene chloride use and elimination and/or replacement. Fifteen of the 17 companies had either eliminated (10) or reduced to below 10,000 lbs/yr (5) their use of methylene chloride at the time of the survey in 2000. Many of the surveyed companies moved to aqueous cleaning from methylene chloride degreasing operations. Environmental concerns were the most popular reason given for eliminating or reducing use of methylene chloride. Worker health and safety concerns, especially concern about compliance with the 1997 Occupational Safety and Health Administration methylene chloride standard, were also a motivation. In general, the companies associated many benefits and few problems with eliminating or reducing use of methylene chloride. Exposure reduction strategies based on toxics use reduction techniques appear to be feasible for many manufacturing companies. However, research should be conducted to assess the introduction of new hazards as a result of tightened regulations on methylene chloride.