In order to investigate a possible occupational etiology of chronic disorders of the haematopoietic system in line with the German occupational diseases regulation, No. 1303 of appendix 1 (diseases caused by benzene, its homologues, or by styrene), individual assessment of the internal benzene exposure is necessary. Especially the retrospective estimation of percutaneous benzene absorption has caused problems in this context. The present paper evaluates scientific data from in vitro and in vivo studies of dermal penetration of benzene. On the basis of medical and toxicological considerations, pragmatic proposals are derived for a simplified calculation method for assessing the internal load resulting from percutaneous benzene uptake. It seems to be adequate in most cases to assume a dermal benzene penetration rate of 1 mg/cm²/h for exposed workers.
