Poster Presentation Abstract

Title: Using a Physical-Chemical Mathematical Exposure Model for Determination of Occupational Exposure

Authors: Marc J. Plisko, John W. Spencer

Presented at: AIHce 2004, Atlanta, GA

Measurement and monitoring of occupational exposure have traditionally been performed using validated air sampling and analytical methods. Physical-chemical mathematical models have also been used for occupational exposure assessment, most often in circumstances where air monitoring is either not possible or would only provide limited data due to minimal available resources.

Mechanics commonly use petroleum distillate-based solvents to penetrate and dislodge rusty bolts, nuts and other metal parts during maintenance activities. Commercial preparations of a commonly used petroleum-distillate product have been reported to contain varying quantities of benzene. The purpose of this study was to use predictive modeling in conjunction with traditional air monitoring to predict and determine the exposure of a mechanic and his helper to benzene vapors when using a benzene-containing petroleum solvent.

The benzene exposure to the mechanic and his helper was evaluated using traditional breathing zone air monitoring. The Near-Field Far-Field (two-compartment) physical-chemical mathematical model was used to predict the exposure concentration. Such methods were used in tandem since only one exposure period was monitored and the potential variability of the exposure data was unknown. Furthermore, variables such as quantity of solvent being used and air flow through the near-field may be described when modeling the work practices but are not necessarily accounted for when evaluating the results of air sampling.

The results of the predictive modeling were within a factor of four, and less than one order of magnitude, of the actual measured results. For the purposes of this evaluation, neither the breathing zone determination nor the mathematical model was considered to be more appropriate than the other. Each of these methods was considered an important tool for characterizing or predicting the potential and measured exposure.

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