Quantitative determination of urinary metabolites of o-dichlorobenzene using a gas chromatograph

o-Dichlorobenzene (o-DCB) is used as an organic solvent, as a chemical intermediate, and as a heat transfer medium. In humans, o-DCB is metabolized to 2,3- and 3,4-dichlorophenols, and 3,4- and 4,5-dichlorocatechols, and these metabolites are eliminated via the kidneys. In this study, we tried to determine the concentrations of urinary 2,3- and 3,4-dichlorophenols using a gas chromatograph (GC). When control urine specimens were spiked at concentrations of 10, 20 and 40 mg/l, the mean recovery rates of 2,3- and 3,4-dichlorophenols were 98.3 to 101.9% (CV = 4.0 to 4.8%) and 100.6 to 105.4% (CV = 2.5 to 7.0%), respectively. Next, urine samples collected from ten male workers exposed to o-DCB were analyzed. The concentrations of urinary 2,3- and 3,4-dichlorophenols determined by the GC method closely agreed with those by the HPLC method, which we had developed in a previous study, and these metabolite concentrations were linearly correlated to the 8-h TWA values of o-DCB in the range of 0.1 to 2.3 ppm. Consequently, the GC method can be used for biological monitoring of o-DCB, though it is necessary that the linear relation is confirmed in a higher range of exposure.