Carcinogenic Risk of Benzene Derived from Animal and Human Data

Benzene is widely considered to be an animal and human carcinogen but there are wide-ranging estimates of its potency. Risk assessments of benzene and human leukemia have primarily focused on exposure by inhalation over an occupational lifetime. The Food and Drug Administration (FDA) regulates benzene as a contaminant in food additives and thus is interested in the risk from lifetime exposure by the oral route. The risk from lifetime ingestion of benzene is assessed using the NTP animal gavage studies and the National Institute of Occupational Safety and Health (NIOSH) epidemiology studies, and the results are compared. The unit risks derived from the human epidemiology data for leukemia are similar to those derived from the rodent data when the animal risks are summed over all organ sites in each sex grouping. The collective unit risk values calculated from the animal data were.038 and.039 per mg/kg body weight/day exposure for male and female mice, respectively. The unit risks calculated from the human epidemiology data were.043 and.024 per mg/kg body weight/day exposure using the relative and absolute risk models, respectively.