National Institute for Occupational Safety and Health, Industrywide Studies Branch, Division of Surveillance, Hazard Evaluations and Field Studies, Cincinnati, Ohio, USA.
J Occup Environ Hyg. 2012;9(8):478-90. doi: 10.1080/15459624.2012.693836.
The National Institute for Occupational Safety and Health previously conducted a retrospective cancer incidence and mortality study of workers employed at a rubber chemical manufacturing plant. Compared with New York State incidence, the bladder cancer risk was 6.5 times higher for workers considered to have definite exposure to ortho-toluidine and aniline, and 4 times higher for workers with possible exposure. Exposure characterization in the original study utilized a surrogate measure based only on departments in which each worker was ever employed. As part of an update of that study, some departments in the three original exposure groups were reclassified based on a follow-up site visit; interviews with employees, management, and union representatives; and review of records including exposure data. An additional evaluation of department-job combinations, rather than only departments, was used to stratify exposure into four categories. An approximate rank of "relative" exposure level for each department-job-year combination was also assigned using a ranking scale of 0 to 10. The ranks were supported by quantitative exposure levels and by professional judgment. The numerical ranking scale was applied to each worker by multiplying the exposure rank by duration for each job held based on comprehensive individual work histories. The cumulative rank scores for this cohort ranged from 0 to 300 unit-years. The medians of the cumulative rank scores for the exposure categories showed very good agreement with increasing exposure classifications (e.g., 0.72, 4.6, 11, 14 unit-years for the four exposure categories). Workers' breathing zone air sampling data collected at this plant from 1976-2004 were well below published occupational exposure limits for these chemicals, but additional cases of bladder cancer have been reported. The exposure assessment revisions and rank estimates will be used to analyze the updated bladder cancer incidence data.
美国国家职业安全与健康研究所曾对一家橡胶化学品制造厂的工人进行过一项癌症发病率和死亡率的回顾性研究。与纽约州的发病率相比，被认为有明确邻甲苯胺和苯胺接触史的工人膀胱癌风险高出 6.5 倍，可能接触过的工人膀胱癌风险高出 4 倍。在最初的研究中，暴露特征的描述仅基于每个工人曾经工作过的部门，使用了一种替代测量方法。作为该研究更新的一部分，根据后续现场访问、与员工、管理层和工会代表的访谈，以及对包括暴露数据在内的记录的审查，对三个原始暴露组中的一些部门进行了重新分类。使用了一种额外的部门-工作组合评估方法，而不仅仅是部门，将暴露分为四个类别。还使用了一种从 0 到 10 的排名量表，为每个部门-工作年组合分配了近似的“相对”暴露水平排名。排名得到了定量暴露水平和专业判断的支持。使用排名量表将每个工人的暴露排名乘以每个工作的持续时间，每个工作的持续时间都基于综合的个人工作历史。该队列的累积排名分数范围从 0 到 300 个单位年。暴露类别的累积排名分数中位数与暴露分类呈很好的一致性（例如，四个暴露类别中的累积排名分数中位数分别为 0.72、4.6、11 和 14 个单位年）。该工厂从 1976 年至 2004 年收集的工人呼吸区空气采样数据远低于这些化学物质的公布职业接触限值，但仍有额外的膀胱癌病例报告。暴露评估修订和排名估计将用于分析更新的膀胱癌发病率数据。
