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Questions persist regarding assessment of workers' exposures to products containing low levels of benzene, such as mineral spirit solvent (MSS). This study summarizes previously unpublished data for parts-washing activities, and evaluates potential daily and lifetime cumulative benzene exposures incurred by workers who used historical and current formulations of a recycled mineral spirits solvent in manual parts washers. Measured benzene concentrations in historical samples from parts-washing operations were frequently below analytical detection limits. To better assess benzene exposure among these workers, air-to-solvent concentration ratios measured for toluene, ethylbenzene, and xylenes (TEX) were used to predict those for benzene based on a statistical model, conditional on physical-chemical theory supported by new thermodynamic calculations of TEX and benzene activity coefficients in a modeled MSS-type solvent. Using probabilistic methods, the distributions of benzene concentrations were then combined with distributions of other exposure parameters to estimate eight-hour time-weighted average (TWA) exposure concentration distributions and corresponding daily respiratory dose distributions for workers using these solvents in parts washers. The estimated 50th (95th) percentile of the daily respiratory dose and corresponding eight-hour TWA air concentration for workers performing parts washing are 0.079 (0.77) mg and 0.0030 (0.028) parts per million by volume (ppm) for historical solvent, and 0.020 (0.20) mg and 0.00078 (0.0075) ppm for current solvent, respectively. Both 95th percentile eight-hour TWA respiratory exposure estimates for solvent formulations are less than 10% of the current Occupational Safety and Health Administration permissible exposure limit of 1.0 ppm for benzene.

We reanalyzed the Libby vermiculite miners' cohort assembled by Sullivan to estimate potency factors for lung cancer, mesothelioma, nonmalignant respiratory disease (NMRD), and all-cause mortality associated with exposure to Libby fibers. Our principal statistical tool for analyses of lung cancer, NMRD, and total mortality in the cohort was the time-dependent proportional hazards model. For mesothelioma, we used an extension of the Peto formula. For a cumulative exposure to Libby fiber of 100 f/mL-yr, our estimates of relative risk (RR) are as follows: lung cancer, RR = 1.12, 95% confidence interval (CI) =[1.06, 1.17]; NMRD, RR = 1.14, 95% CI =[1.09, 1.18]; total mortality, RR = 1.06, 95% CI =[1.04, 1.08]. These estimates were virtually identical when analyses were restricted to the subcohort of workers who were employed for at least one year. For mesothelioma, our estimate of potency is K(M) = 0.5 x 10(-8), 95% CI =[0.3 x 10(-8), 0.8 x 10(-8)]. Finally, we estimated the mortality ratios standardized against the U.S. population for lung cancer, NMRD, and total mortality and obtained estimates that were in good agreement with those reported by Sullivan. The estimated potency factors form the basis for a quantitative risk assessment at Libby.

Background: Prior studies of cardiac rhythm management devices (pacemakers [PM] and implantable cardioverter defibrillators [ICD]) utilization in the United States have been limited to the Medicare population. We evaluated the national trends for the implantation of PMs and ICDs including the burden of device replacement. Methods: The Nationwide Inpatient Sample was queried to identify PM and ICD patients between 1993 and 2006 using ICD-9-CM codes, including demographics, health profile, and economic data. The Charlson Comorbidity Index (CCI) and replacement burden were calculated, and changes over time studied. Results: From 1993 to 2006, 2.4 million patients received a primary PM and 0.8 million received an ICD, while there were 369,000 PM replacements and 74,000 ICD replacements. Women comprised 49% of PM and 24% of ICD patients. The mean ICD replacement burden was 8.4% (range 5–22%) and decreased significantly over time (P < 0.0001) while the replacement burden for PMs was constant (mean = 13.4%, range 11–16%). ICD patients had more comorbidities than PM patients (CCI: 0.8 vs 1.1, P < 0.0001). Conclusions: The replacement burden for PMs has remained constant, while the replacement burden for ICDs has decreased. This is likely due to the stability of the patient population receiving PMs and technology maturity. Alternatively, the indications for ICD implantation have broadened, resulting in an increased number of primary ICD implantations. The age and comorbidities are increasing in those patients receiving ICDs while the PM population is stable. These data suggest that monitoring of replacement burden is warranted, given the changing populations, their disparate clinical outcomes, and economic implications to the health care system. (PACE 2010; 33:705–711)

Background Occupational sprain and strain injuries are one of the most common types of nonfatal occupational injuries and a significant source of lost workdays. This study examines factors associated with severe work-related sprain/strain injuries to the back, shoulder, and knees. Methods A synthetic case–control study was performed (controls were selected from the same pool of utility workers as cases). Cases included all electric utility workers who had experienced a severe work-related sprain/strain injury to the back, knee, or shoulder. Primary controls were selected from all workers who had sustained a minor injury. Secondary controls were selected from employees with a minor sprain/strain injury to the back, knee, or shoulder. Multivariate logistic regression models were used to estimate odds ratios and 95% confidence intervals. Results Workers 41 years and older were more likely to have experienced severe shoulder sprain/strain injuries [Age 41–50: OR = 3.62, 95% CI: 1.71–7.65; age 51 and older: OR = 4.49, 95% CI: 1.89–10.67] and severe back sprain/strain injuries [Age 41–50: OR = 1.70, 95% CI: 1.06–2.33; age 51 and older: OR = 1.5, 95% CI: 0.90–2.52]. Line workers and maintenance workers had an increased risk of serious sprain/strain injuries. Gender and day of week were not significantly associated with sprain/strain injuries. Discussion Though this study is limited by available data, future studies may benefit from this preliminary examination of occupational and demographic characteristics associated with serious sprain/strain injuries among electric utility workers. Am. J. Ind. Med. 52:210–220, 2009. © 2008 Wiley-Liss, Inc.

BACKGROUND Ionizing radiation has been used since the 1950s to treat a variety of cancers. Cancer patients who are treated with radiotherapy have shown increased risks for a variety of second malignancies, including mesothelioma, in several recent reports. The only existing study of Hodgkin lymphoma (HL) and subsequent mesothelioma had a short observation period. METHODS The authors used Surveillance, Epidemiology, and End Results data over a 30-year period to identify patients with HL and non-Hodgkin lymphoma (NHL) who also were diagnosed with mesothelioma. Standardized incidence ratios (SIR) and absolute excess risks were calculated by sex and treatment modality for both types of lymphoma. RESULTS Twenty-six patients were identified who had mesothelioma as second primaries based on 21,881 diagnoses of HL and 101,001 diagnoses of NHL. There was a statistically significant increase in mesothelioma (4 diagnoses; SIR, 6.59; 95% confidence interval [95% CI], 1.79–16.87) among men with HL who received radiation, but no women survivors were identified who had a diagnosis of mesothelioma. For NHL survivors, there was a nonsignificant excess of mesothelioma among men (SIR, 1.91; 95% CI, 0.77–3.93) and women (SIR, 3.75; 95% CI, 0.77–10.95) who had received radiation treatment. There were no increases among patients who were unirradiated. CONCLUSIONS Mesothelioma rates for patients who had received radiotherapy were increased for survivors of HL and NHL. No increases were observed among the unirradiated. These findings and the existing body of supporting studies confirmed that radiotherapy is a cause of mesothelioma. Cancer 2007. © 2007 American Cancer Society.

The U.S. Environmental Protection Agency has begun discussions to consider its assessment of asbestos toxicity related to mineral form and fiber size. Brake workers are typically exposed to short chrysotile fibers. To explore the mesothelioma risk among brake workers, considering other occupational exposures to asbestos, data from a study that was published previously were obtained and the analysis was extended. The National Cancer Institute provided data from a case-control study of mesothelioma. Because many participants with a history of brake work also had employment in other asbestos-related occupations, mesothelioma cases and controls were compared for a history of brake work, controlling for employment in eight occupations with potential asbestos exposure. A stratified analysis was also performed excluding those with any of the eight occupations. Possible interactions between brake work and other occupational exposures related to risk of mesothelioma were also examined. The odds ratio (OR) for employment in brake installation or repair was 0.71 (95% CI: 0.30-1.60) when controlled for insulation or shipbuilding. When a history of employment in any of the eight occupations with potential asbestos exposure was controlled, the OR was 0.82 (95% CI: 0.36-1.80). ORs did not increase with increasing duration of brake work. Exclusion of those with any of the eight exposures resulted in an OR of 0.62 (95% CI: 0.01-4.71) for occupational brake work. There was no evidence of an interaction between brake work and other occupational exposures. These latter analyses were based on small numbers of exposed cases. The results are consistent with the existing literature indicating that brake work does not increase the risk of mesothelioma and adds to the evidence that fiber type and size are important determinants of mesothelioma risk.