Assessing exposure to dinitrotoluene using a biological monitor

Exposure of workers to dinitrotoluene (DNT) was evaluated at a DNT manufacturing plant. Urine was collected over 72 hours; work diaries were prepared dialy; breathing zone air was sampled; and skin and environmental surfaces were wiped. Chemical analysis was performed using gas chromatography or gas chromatography/mass spectrometry. Proportions of urinary DNT and metabolites deviated substantially from those reported in rats exposed to 2,4-DNT; but as with rats, females appeared to excrete considerably more dinitrobenzyl glucuronide. Between persons on any one day and within persons on different days, considerable variation existed in the proportions of metabolites excreted. The peak rate of excretion was likely to occur toward the end of a work shift or shortly afterward. Most urinary metabolites related to exposure during an eight-hour shift had been excreted by the start of work the following day. Estimates of the maximum one-day exposure incurred by a participant in this study ranged from 0.24 to 1.00 mg of technical-grade DNT per kilogram of body weight. A large proportion of the DNT absorbed by DNT operators and loaders, it is suggested, may have entered through the skin or the gastrointestinal tract.