Abstract:
Occupational exposure to multiple volatile organic compounds (VOCs) from the use of spray guns is widespread in the wood-finishing industry. VOCs in exhaled breath used as abiological sample for exposure have been shown to correlate with ambient air concentrations. Comparing a worker’s exposure by environmental monitoring and biomonitoring using exhaled breath would determine the actual dose the worker is receiving and whether the worker is properly protected. In this study 20 workers at two wood-finishing plans were sampled for workday breathing zone exposure to VOCs. Exhaled breath was also collected from each worker over a 24-hour period and analyzed for VOCs. Observations of work environment, tasks, ventilation and PPE were recorded for each worker. Individual characteristics among workers including weight, body fat, and heart rate were measured and used to test a physiologically based toxicokinetic (PBTK) model. All breathing zone sampling showed VOC concentrations below regulatory standards. For the majority of workers, exhaled breath VOC concentrations were low before the start of the work shift, gradually increased throughout the workday, and then returned to the baseline concentration 24 hours later. Correlation between breathing zone and exhaled breath concentration of the toluene, acetone, and xylenes were good. The prediction model shows inter-individual variability also plays a role in interpreting biomonitoring data and breathing zone exposure alone cannot always predict inhaled dose. The five compartment PBTK model overall underestimated measured exhaled breath concentration of toluene the day after exposure.