title: Variation in exposure levels for high hazard frequently monitored agents.
abstract: Assumptions about the underlying distribution of occupational exposures are important to the practice of industrial hygiene. They affect decisions on exposure monitoring strategies, the interpretation of monitoring results, and the degree of protection provided by occupational exposure limits and action levels. However, there is little published data validating these assumptions. Strict exposure limits for three highly hazardous agents, asbestos, beryllium, and ionizing radiation, led to frequent monitoring of occupational exposure levels. Consequently, sets of hundreds to thousands of exposure measurements are available for analysis. Statistical analysis of these data sets indicates that within-worker variation, as measured by geometric standard deviation (GSD), tend to be higher than is generally assumed for occupational exposures. The success of health protection programs in identifying and controlling predictable sources of exposure through frequent monitoring is offered as a possible explanation for the relatively high variation observed in these data sets. Despite the high exposure variation, arithmetic mean levels and the percentage of measurements exceeding exposure limits were low, indicating that a large GSD does not imply that working conditions are unacceptable. However, more frequent monitoring is required to assure exposures are acceptable. This article also presents an adaptation of graphical methods, using probability plotting and linear regression, to estimate the distribution parameters of a data set that contains a high percentage of nondetected results.
authors.affiliation: U.S. Department of Energy, EH-6, 270 CC, 199901 Germantown Road, Germantown, MD 20874, USA.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Wambach
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000704:Analysis of Variance; D001194:Asbestos / Q000032:analysis; D001608:Beryllium / Q000032:analysis; D004784:Environmental Monitoring / Q000592:standards*; D006801:Humans; D008452:Maximum Allowable Concentration; D016273:Occupational Exposure / Q000032:analysis*; D011829:Radiation Dosage; D012308:Risk Management
chemical_list: D000393:Air Pollutants; D001194:Asbestos; D001608:Beryllium