Glass D C, Adams G G, Manuell R W, Bisby J A
Occupational Hygiene Unit, Faculty of Science and Technology, Deakin University, Victoria 3217, Geelong, Australia.
Ann Occup Hyg. 2000 Jun;44(4):301-20.
An excess of lympho-haematopoietic (LH) cancers has been identified in the Australian petroleum industry through the Health Watch surveillance programme. A nested case-control study is being conducted to investigate this excess. This paper describes the methods used to provide quantitative estimates of benzene exposure for each of the subjects in the case-control study. Job histories were compiled for each subject from interviews and company employment records. Site visits and telephone interviews were used to identify the tasks included in each job title. Details about the tasks such as their frequency, the technology in use and about changes that had taken place over the years were also gathered. Exposure dated back to the late 1940s for a few subjects. Collaborating petroleum companies provided recent benzene exposure monitoring data. These were used to generate Base Estimates of exposure for each task, augmented with data from the literature where necessary. Past exposures were estimated from the Base Estimates by means of an exposure algorithm. The modifying effects of technological changes and changes to the product were used in the algorithm. The algorithm was then computed to give, for each job, for each subject, an estimate of average benzene exposure in ppm in the workplace atmosphere (Workplace Estimate). This value was multiplied by the years for which the job was held and these values summed to give an estimate of Cumulative Estimate of benzene in ppm-years. The occupational hygienists performing the exposure assessment did so without knowledge of the case or control status of subjects. Overall exposures to benzene in the Australian petroleum industry were low, and virtually all activities and jobs were below a time-weighted average of 5 ppm. Exposures in terminals were generally higher than at refineries. Exposures in upstream areas were extremely low. Estimates of Cumulative Estimate to benzene ranged from 0.005 to 50.9 ppm-years.
通过“健康观察”监测项目，在澳大利亚石油行业发现了过多的淋巴造血（LH）癌症病例。目前正在进行一项巢式病例对照研究以调查这一异常情况。本文描述了在病例对照研究中用于对每位受试者的苯暴露进行定量估计的方法。通过访谈和公司就业记录为每位受试者编制工作经历。通过实地考察和电话访谈来确定每个职位所包含的任务。还收集了有关任务的详细信息，如任务频率、使用的技术以及多年来发生的变化。少数受试者的暴露可追溯到20世纪40年代末。合作的石油公司提供了近期的苯暴露监测数据。这些数据用于生成每项任务的暴露基础估计值，并在必要时用文献数据进行补充。过去的暴露情况通过暴露算法从基础估计值中估算得出。该算法考虑了技术变化和产品变化的修正作用。然后计算该算法，为每个职位的每位受试者给出工作场所空气中苯的平均暴露量估计值（工作场所估计值），单位为ppm。将该值乘以从事该工作的年数，然后将这些值相加，得出以ppm - 年为单位的苯累积估计值。进行暴露评估的职业卫生学家在不知道受试者的病例或对照状态的情况下开展工作。澳大利亚石油行业的苯总体暴露水平较低，几乎所有活动和工作的时间加权平均暴露量都低于5 ppm。码头的暴露通常高于炼油厂。上游地区的暴露极低。苯的累积估计值范围为0.005至50.9 ppm - 年。
