[Alveolar air analysis for benzene as a biomonitoring index]

To establish a well validated biological monitoring procedure for benzene exposure, the concentration of benzene in alveolar air and phenol in urine was studied in conjunction with personal monitoring data both in workers and volunteers. There existed good correlation between benzene concentration in alveolar air, phenol concentration in urine by the end of workshift and the benzene concentration in workplace when the exposure level was above 5 mg/m3. When the exposure level was below 5 mg/m3, the urinary phenol was no longer a valid indicator of uptake/exposure in volunteers. The determination of benzene concentration in expired air collected after the workshift was a potentially useful index. The relationship between benzene concentration in alveolar air collected after shift and environmental air declined when the exposure level was very high (TWA greater than 200mg/m3). In general, the alveolar air analysis was valid as a biomonitoring index of benzene exposure under the exposure concentration ranged 3-120 mg/m3. The lest sampling time of alveolar air appears to be 30 minutes after the cessation of exposure and before the next shift.