Design and evaluation of a breath-analysis system for biological monitoring of volatile compounds

To ensure the health and safety of workers, integrated industrial hygiene m ethodologies often include biological monitoring of the workers to help und erstand their exposure to chemicals. To this end, a field-portable breath-a nalysis system was developed and tested to measure selected solvents in exh aled air. The exhaled breath data were evaluated using a physiologically ba sed pharmacokinetic (PBPK) model to relate exposure to tissue dose. The sys tem was designed to monitor workers every time they entered or left a work environment-a vast improvement over current 8-hour integrated monitoring st rategies. The system combines (1) chemical dosimeters to measure airborne c ontaminant levels (analyzed in the field/ workplace); (2) real-time breath analysis to quantitate exposure; and 3) PBPK models to estimate internal ta rget tissue dose. To evaluate the system, field tests were conducted at two locations: (1) at an incinerator in Tennessee monitoring benzene and tolue ne exposures; and (2) a waste repackaging facility in Washington State wher e hexane, trimethylbenzene, and methylene chloride was monitored. Exhaled b reath was sampled and analyzed before and after each specific job task, whi ch ranged from 15 min to 8 hours in duration. In both field studies several volunteers had posttask breath levels higher than pretask levels. The grea test increase corresponded to 573 ppb for methylene chloride and 60 ppb for toluene. Compared with breath analysis, the chemical dosimeters underpredi cted the dosimetry, particularly for longer sampling intervals when the vol ume of air sampled may have diluted exposures. The results of the field stu dies illustrate the utility of monitoring workers for exposures throughout the day, particularly when job-specific tasks may indicate a potential for exposure.