Symanski E, Kupper L L, Rappaport S M
University of Texas Health Science Center, Houston, School of Public Health 77030, USA.
Occup Environ Med. 1998 May;55(5):300-9. doi: 10.1136/oem.55.5.300.
To conduct a comprehensive evaluation of long term changes in occupational exposure among a broad cross section of industries worldwide.
A review of the scientific literature identified studies that reported historical changes in exposure. About 700 sets of data from 119 published and several unpublished sources were compiled. Data were published over a 30 year period in 25 journals that spanned a range of disciplines. For each data set, the average exposure level was compiled for each period and details on the contaminant, the industry and location, changes in the threshold limit value (TLV), as well as the type of sampling method were recorded. Spearman rank correlation coefficients were used to identify monotonic changes in exposure over time and simple linear regression analyses were used to characterise trends in exposure.
About 78% of the natural log transformed data showed linear trends towards lower exposure levels whereas 22% indicated increasing trends. (The Spearman rank correlation analyses produced a similar breakdown between exposures monotonically increasing or decreasing over time.) Although the rates of reduction for the data showing downward trends ranged from -1% to -62% per year, most exposures declined at rates between -4% and -14% per year (the interquartile range), with a median value of -8% per year. Exposures seemed to increase at rates that were slightly lower than those of exposures which have declined over time. Data sets that showed downward (versus upward) trends were influenced by several factors including type and carcinogenicity of the contaminant, type of monitoring, historical changes in the threshold limit values (TLVs), and period of sampling.
This review supports the notion that occupational exposures are generally lower today than they were years or decades ago. However, such trends seem to have been affected by factors related to the contaminant, as well as to the period and type of sampling.
对全球广泛行业的职业暴露长期变化进行全面评估。
对科学文献进行综述，找出报告暴露历史变化的研究。汇编了来自119篇已发表和若干未发表来源的约700组数据。数据在30年期间发表于涵盖一系列学科的25种期刊上。对于每个数据集，汇总每个时期的平均暴露水平，并记录污染物、行业和地点的详细信息、阈限值（TLV）的变化以及采样方法的类型。使用斯皮尔曼等级相关系数来识别暴露随时间的单调变化，并使用简单线性回归分析来表征暴露趋势。
约78%经自然对数转换的数据显示出暴露水平呈下降的线性趋势，而22%显示出上升趋势。（斯皮尔曼等级相关分析在随时间单调增加或减少的暴露之间产生了类似的分类。）尽管显示下降趋势的数据的下降速率为每年-1%至-62%，但大多数暴露以每年-4%至-14%的速率下降（四分位间距），中位数为每年-8%。暴露似乎以略低于随时间下降的暴露速率增加。显示下降（与上升）趋势的数据集受到多种因素的影响，包括污染物的类型和致癌性、监测类型、阈限值（TLV）的历史变化以及采样时期。
本综述支持以下观点，即如今的职业暴露总体上低于数年或数十年前。然而，这种趋势似乎受到与污染物以及采样时期和类型相关的因素的影响。
