Breath concentration as an index of the health risk from benzene. Studies on the accumulation and clearance of inhaled benzene.

Abstract

Human subjects were exposed to known concentrations of benzene [a carcinogen] in air for single and repeated daily periods. The breath concentrations measured during repeated exposures approached a maximum after 3 days, and this phenomenon indicated that the tissues were approaching saturation under the experimental conditions. The breath concentrations measured after exposure indicated an initial rapid clearance of benzene with a half-time of 2.6 h, followed by a slower phase with a half-time of 24 h. The decay in breath concentration after prolonged occupational exposure was slower; the difference between the laboratory and industrial studies was not significant. The hygienic significance of these results is discussed, and it is recommended that control measures be employed when a morning breath concentration exceeds 10 ppb.