PNNL

Abstract

To ensure the health and safety of workers, integrated industrial hygiene methodologies often include biological monitoring of the workers to better understand their exposure to chemicals. To this end, a field-portable breath-analysis system was developed and tested to measure selected solvents in exhaled air. The exhaled breath data was evaluated using a physiologically based pharmacokinetic (PBPK) model to relate exposure to tissue dose. The system was designed to monitor workers every time they enter and leave a work environment - a vast improvement over current 8-hr integrated monitoring strategies. The system combines 1) chemical dosimeters to measure airborne contaminant levels; these dosimeters are analyzed in the field/workplace; 2) real-time breath analysis to quantitate exposure; and 3) PBPK models to estimate internal target tissue dose. To evaluate the system, field tests were conducted at two locations: 1) at an incinerator in Tennessee monitoring benzene and toluene exposures; and 2) hexane, trimethylbenzene, and methylene chloride monitoring at a waste repackaging facility in Washington. Exhaled breath was sampled and analyzed before and after each specific job task, which ranged from 15 minutes to 8 hours in duration. In both field studies, several volunteers had post-task breath levels higher than pre-task levels. The greatest increase corresponded to 573 ppb for methylene chloride and 60 ppb for toluene. Compared to breath analysis, the chemical dosimeters underpredicted the dosimetry, particularly for longer sampling intervals where the volume of air sampled may have diluted exposures. The results of the field studies illustrate the utility of monitoring workers for exposures throughout the day, particularly when job-specific tasks may indicate a potential for exposure.