The testimony reviewed the history of benzene (71432) exposure and the development of recommended exposure limits. Data were reviewed on pharmacokinetics, cytotoxicity, long and short term exposures, and skin absorption of benzene. Benzene or its metabolites have been shown to remain in the body for a long period of time following inhalation exposure. Studies in mice revealed exposure related increases in the frequency of sister chromatid exchanges and micronuclei at all exposure concentrations. Some epidemiological standards relating to the benzene standard were cited, including data from the Goodyear rubber hydrochloride cohort which implied a relation between 1 part per million (ppm) benzene exposure for 40 years and incidence of leukemia. Other studies linked benzene to multiple myeloma and myelofibrosis. NIOSH recommended that the Permissible Exposure Limit for benzene be reduced to 0.1ppm as an 8 hour time weighted average and that there be a limit on short term exposures of 1.0ppm for any 15 minute period. These recommendations were made to protect against inhalation of benzene and did not relate to skin absorption. Reports indicated that significant benzene absorption can result among workers exposed to solvents containing about 0.5 percent benzene. It was recommended that steps be taken to eliminate this route of exposure. The use of pressure demand supplied air respirators with an auxiliary self contained breathing apparatus or a pressure demand apparatus was recommended.