Occupational exposure, retrospective

Respiratory Effects. No studies were located regarding respiratory effects in humans after inhalation exposure to 1,3,5-TNB. One retrospective study (Okubo and Shigeta 1982) of acute occupational exposure to 1,3-DNB dust particles was located. Six workers were removing crystallized 1,3-DNB from a tank and were protected with gauze masks and rubber gloves. Exposure occurred over a period of 6 days. By the end of the exposure period, some of the workers complained of slight dyspnea upon exertion. Inhalation was considered to be a primary route of exposure because a relatively small skin area (face and neck) was exposed. Limitations of this study include lack of information on the concentration of 1,3-DNB in the air, the amount of particulate 1,3-DNB deposited on workers skin, and the exact duration of exposure. 

A retrospective assessment of the potential antifertility influence of ethylene dibromide was conducted by studying the reproductive perfonnance of men exposed to ethylene dibromide in the workplace. Data were obtained from four chemical plants manufacturing ethylene dibromide located in the southern part of the United States (Arkansas and Texas). Exposures in the plants ranged from less than 0.5 ppm to 5 ppm [3.8-38 mg/m- ]. Evaluations were made exclusively on the basis of the men s reproductive histories of live births to their wives, subsequent to their occupational exposure. The mmiber of live births was compared with the expected mmiber derived from national fertility tables. One of the four plants studied showed a significant decrease in fertility however, when data from the four plants were combined, there was no significant effect of ethylene dibroniide exposure on reproductive performance (Wong et al., 1979). 

Occupational exposure to chromium(VI) compounds in a number of industries has been associated with increased risk of respiratory system cancers, primarily bronchogenic and nasal. Among the industries investigated in retrospective mortality studies are chromate production, chromate pigment production and use, chrome plating, stainless steel welding, ferrochromium alloy production, and leather tanning. 

Pastides H, Austin R, Lemeshow S, et al. 1994. A retrospective-cohort study of occupational exposure to hexavalent chromium. Am J Ind Med 25 663-675. 

McNamee, R. (1996). Retrospective assessment of occupational exposure to hydrocar-bons-job-exposure matrices versus expert evaluation of questionnaires, Occup. Hyg., 3, 137-143. 

Benke, G., Sim, M., Forbes, A., and Salzberg, M. (1997). Retrospective assessment of occupational exposure to chemicals in community-based studies Validity and repeatabiUty of industrial hygiene panel ratings. Int J Epidemiol 26, 635-642. 

Bouyer, J., and Hemon, D. (1993). Retrospective evaluation of occupational exposures in population-based case-control studies General overview with special attention to job exposure matrices. Int J Epidemiol 22(Suppl 2), S57-S64. 

Siemiatycki, J., Fritschi, L., Nadon, L., and Gerin, M. (1997). Reliability of an expert rating procedure for retrospective assessment of occupational exposures in community-based case—control studies. Am J Ind Med 31, 280-286. 

A retrospective cohort study of 14,457 aircraft maintenance woikers at Hill Air Force Base, Utah, was undertaken by Spirtas et al. (1991) to determine if occupational exposure to over 20 solvents, including trichloroethylene and tetrachloroethylene, posed an increased risk of mortality. Deaths due to multiple myeloma or non-Hodgkin s lymphoma were elevated in female woikers exposed to tetrachloroethylene for at least 1 year. However, confidenee in these data is low primarily beeause multiple and overlapping exposure to more than one chemieal was considerable. In addition, the levels of tetrachloroethylene to which the workers were exposed were not provided, and lifestyle factors such as smoking and alcohol consumption were not assessed. 

Retrospective mortality studies99 in 2,567 workers (> 3 months employment) from two capacitor manufacturing plants showed that mortality in both plants was lover than expected and there were no significant increases in either liver or rectal cancer. A study on 31 workers exposed to Aroclor 1254 and other chemicals vtiile employed in a New Jersey petrochemical plant 100 showed an increased incidence of malignant melanomas (0.04% expected 0.13% observed) however, due to the small populations involved in this survey, more comprehensive long term epidemiologic studies will be required to fully assess the carcinogenicity of PCBs. Hovever, it is apparent from most reports that occupational exposure to PCBs results in characteristic toxic symptoms vhich appear to be reversible. 

A retrospective case-control study conducted in humans compared spontaneous abortion rates among women who had been exposed occupationally or nonoccupationally to trichloroethylene and other solvents to rates among women without solvent exposure (Windham et al. 1991). The authors observed approximately three times the risk of spontaneous abortion with exposure to trichloroethylene. This risk increased further when women with less than a half hour of exposure to trichloroethylene each week were excluded from the analysis. However, a consistent dose-response relationship was not observed, and most of the women were exposed to a variety of solvents, not just trichloroethylene. 

Environmental Exposure. In addition to the occupational studies, a retrospective environmental epidemiology study was conducted of 810 lung cancer deaths in residents of a county in Sweden where two ferrochromium alloy industries are located. No indication was found that residence near these industries is associated with an increased risk of lung cancer (Axelsson and Rylander 1980). 

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