Dermal absorption of benzene: implications for work practices and regulations

Because the risk of leukemia for workers exposed to 1 ppm of benzene for 40 years is estimated to be 70% greater than the risk for unexposed persons, the National Institute for Occupational Safety and Health (NIOSH) and the American Conference of Governmental Industrial Hygienists (ACGIH) recommend that the allowable airborne exposure level be 0.1 ppm. Using an experimentally determined dermal flux (permeability) value for benzene through skin, the authors calculated the amount of benzene absorbed through a known surface area (e.g., hands) during exposures where solvents contaminated with benzene were used for cleaning. Even at current contamination levels, which are less than 0.1% in most products, the amount of benzene absorbed through the skin over a long period can be significant, depending on exposure time and exposed skin surface areas. In the example given, the risk for leukemia was increased by 42%. Therefore, the authors recommend that the liquid benzene concentration that triggers labeling, worker education, and protective measures to minimize skin exposure be reduced from 0.1% to 0.01%.