National Institute of Occupational Health, Oslo, Norway.
J Occup Environ Hyg. 2012;9(4):230-41. doi: 10.1080/15459624.2012.666189.
The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silicon carbide industry. More than 3300 historical total dust measurements were available (1967-2005); however, there were few measurements of other agents. Total dust measurements were therefore used as the basis for the JEM, and a novel method was developed to estimate exposure to other agents. Multiple linear regression models were developed to describe historical exposure to total dust. Exposure estimates were extrapolated backward to periods without exposure data by adjustments for process and work-hour related changes. An exposure assessment study was performed where total dust was sampled in parallel with fibers or respirable dust. The respirable dust was analyzed for the content of quartz, cristobalite, and silicon carbide. Mixed-effect models were developed to estimate the exposure to these agents from total dust exposure, plant, and job group. Exposure to asbestos and polycyclic aromatic hydrocarbons was assigned qualitatively. Multiple linear regression models of total dust described historical exposure best in the furnace department (R(2) (adj) = 0.49-0.74). Models in the other departments explained less variance (R(2) (adj) = 0.12-0.32). Exposure determinants and total dust explained a substantial proportion of the between- (70-100%) and within-worker (8.0-54%) variance in the mixed-effect models. The relative bias between available historical measurements and the estimated exposure to dust components varied between -39% (fiber) and 40% (quartz). However, corrections were not considered necessary due to limitations in the historical data. The component-specific metrices were sufficiently different from each other (r(Pearson) < 0.7), with the exception of total and respirable dust (r(Pearson) = 0.84) and total dust and cristobalite (r(Pearson) = 0.72), and will enable component-specific epidemiologic analyses in the future. Improved and less correlated estimates of exposure levels for the different components in the dust were obtained with the updated exposure assessment. Due to limitations in the measurement data, assumptions had to be made, especially in the period before 1967. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing tables outlining multiple linear regression models for prediction of total dust exposure in the processing departments of Norwegian SiC producing plants, evaluation of the predictive abilities of the reduced total dust models, and mixed models for pedicting exposure to fibers and respirable quartz, cristobalite, non-fibrous silicon carbide and respirable dust from total dust exposure.].
目的是为挪威碳化硅行业构建一个回溯性职业暴露矩阵（JEM）。有超过 3300 份历史总粉尘测量数据（1967-2005 年）；然而，其他物质的测量数据很少。因此，总粉尘测量数据被用作 JEM 的基础，并开发了一种新的方法来估计其他物质的暴露情况。建立了多个线性回归模型来描述历史上总粉尘的暴露情况。通过调整与工艺和工作时间相关的变化，将暴露估计值外推到没有暴露数据的时期。进行了一项暴露评估研究，在该研究中，同时对总粉尘、纤维或可吸入粉尘进行采样。对可吸入粉尘进行了分析，以测定石英、方石英和碳化硅的含量。建立了混合效应模型，以从总粉尘暴露、工厂和作业组估计这些物质的暴露情况。石棉和多环芳烃的暴露情况定性分配。炉膛部门的总粉尘多元线性回归模型（调整后 R^2(adj) = 0.49-0.74）对历史暴露情况的描述最佳。其他部门的模型解释的方差较小（调整后 R^2(adj) = 0.12-0.32）。暴露决定因素和总粉尘解释了混合效应模型中工人之间（70-100%）和工人内（8.0-54%）方差的很大一部分。可用历史测量值与估计的粉尘成分暴露之间的相对偏差在-39%（纤维）至 40%（石英）之间。然而，由于历史数据的限制，认为不需要进行修正。各成分的特定指标彼此之间差异较大（皮尔逊相关系数（r）<0.7），除了总粉尘和可吸入粉尘（r = 0.84）以及总粉尘和方石英（r = 0.72）之外，这将使未来能够进行各成分的特定流行病学分析。使用更新的暴露评估方法，获得了粉尘中不同成分的暴露水平的改进和相关性更低的估计值。由于测量数据的限制，特别是在 1967 年之前，必须做出假设。[本文提供了补充材料。请访问职业与环境卫生杂志的出版商在线版本，获取以下免费补充资源：一份包含表格的文件，列出了预测挪威碳化硅生产厂加工部门总粉尘暴露的多元线性回归模型，评估简化后的总粉尘模型的预测能力，以及预测纤维和可吸入石英、方石英、非纤维状碳化硅和总粉尘暴露的可吸入粉尘的混合模型。]
