Experimental evidence for the possible exposure of workers to hexachlorobenzene by skin contamination

The absorption of dermally applied 14C-hexachlorobenzene (14C-HCB; ranging from 2.5 to 2.6 mg/4 cm2) was investigated in the rat. The absorbed portion increased from 1% at six hours to 9.7% at 72 hours after dosing and blood concentrations of 14C increased linearly with time. The rate of absorption was 3.51 (SD 0.81) micrograms/h/4 cm2 and the absorption constant 1.40 (SD 0.33) x 10(-3)/h. Washing with soap at six hours after dosing removed 34% of the dose and decreased absorption by 50% in the next 66 hours. Finally, the compartment model, which incorporated the absorption constant, simulated the time profile of HCB kinetics in blood, and that of cumulative excretion in rats. The model with the absorption constant for the rat was then scaled up for a 70 kg worker, whose exposure was assumed to be exclusively dermal. A rough dermal contamination, which corresponds to the tentative HCB critical blood concentration of 200 ppb, was calculated for different simulated biological half lives. It was 18.2 mg for 100, 5.02 mg for 365, and 2.56 mg for 730 day half lives. The study indicates that dermal contamination can be a source of HCB body burden, and that personal hygiene, such as taking a shower and hand washing is likely to have a profound influence on the body burden of HCB.