Kromhout H, Symanski E, Rappaport S M
Department of Air Quality, Wageningen Agricultural University, The Netherlands.
Ann Occup Hyg. 1993 Jun;37(3):253-70. doi: 10.1093/annhyg/37.3.253.
A database of approximately 20,000 chemical exposures has been constructed in close co-operation between the School of Public Health of the University of North Carolina at Chapel Hill and the Department of Air Pollution of the Wageningen Agricultural University. A special feature of this database is that only multiple measurements of exposure from the same workers were included. This enabled estimation of within- and between-worker variance components of occupational exposure to chemical agents throughout industry. Most of the groups were not uniformly exposed as is generally assumed by occupational hygienists. In fact only 42 out of a total of 165 groups (25%), based on job title and factory, had 95% of individual mean exposures within a two-fold range. On the contrary, about 30% of the groups had 95% of individual mean exposures in a range which was greater than 10-fold. Environmental and production factors were shown to have distinct influences on the within-worker (day-to-day) variability, but not on the between-worker variability. Groups working outdoors and those working without local exhaust ventilation showed more day-to-day variability than groups working indoors and those working with local exhaust ventilation. Groups consisting of mobile workers, those working with an intermittent process and those where the source of contamination was either local or mobile also showed great day-to-day variability. In a multivariate regression model, environment (indoors-outdoors) and type of process (continuous-intermittent) explained 41% of the variability in the within-worker component of variance. Another model, in which only type of process (continuous-intermittent) had a significant effect, explained only 13% of the variability in the between-worker component of variance.
北卡罗来纳大学教堂山分校公共卫生学院与瓦赫宁根农业大学空气污染系密切合作，构建了一个约有20000种化学暴露情况的数据库。该数据库的一个特点是，只纳入了同一工人的多次暴露测量数据。这使得能够估计整个行业内化学制剂职业暴露的工人内部和工人之间的方差成分。大多数组并非如职业卫生学家通常所假设的那样均匀暴露。事实上，在总共165个基于工作头衔和工厂划分的组中，只有42个组（25%）的个体平均暴露量在两倍范围内。相反，约30%的组其个体平均暴露量的95%范围超过10倍。环境和生产因素对工人内部（每日）变异性有明显影响，但对工人之间的变异性没有影响。在户外工作的组以及没有局部排风通风设备的组，其每日变异性比在室内工作的组以及有局部排风通风设备的组更大。由流动工人组成的组、从事间歇式作业的组以及污染源为局部或流动的组，其每日变异性也很大。在一个多元回归模型中，环境（室内 - 室外）和作业类型（连续 - 间歇）解释了方差中工人内部成分变异性的41%。另一个模型中，只有作业类型（连续 - 间歇）有显著影响，该模型仅解释了方差中工人之间成分变异性的13%。
