[Establishment of biological limit value of urinary S-phenylmercapturic acid for occupational exposure to benzene].
OBJECTIVE
To establish the biological exposure limit values of urinary S-phenylmercapturic acid (SPMA) for assessing occupational exposure to benzene.


METHODS
Study participants were selected from 55 workers of benzene exposures below 32.5 mg/m(3). The concentration of personal exposure to benzene was measured by gas chromatography and sampled with personal sampler. The urine samples were collected at the end of work shift and individual internal exposure level was evaluated by determination of SPMA in urine by HPLC/MS method. Comparison of external and internal exposure was assessed by the relative internal exposure (RIE) index.


RESULTS
The benzene exposure level ranged from 0.71 to 32.17 mg/m(3) (geometric mean 6.98 mg/m(3), median 7.50 mg/m(3)). The urinary SPMA at the end of the work shift were significantly correlated with benzene exposure, (microg/g Cr) = -8.625 + 18.367X (mg/m(3)), r = 0.8035, (P < 0.01). According to the occupational exposure limit for benzene in China and calculation of regression equation, the expected value of urinary SPMA was 101.58 microg/g Cr. Mean level of biotransformation of per mg/m(3) benzene to urinary SPMA was 18.23 microg/g Cr and the metabolic efficiencies of benzene transformation to urinary SPMA decreased with benzene exposure increased.


CONCLUSIONS
Based on abroad documents and data, biological limit value for occupational exposure to benzene in China is recommended as follows: 100 microg/g Cr (47 micromol/mol Cr) for SPMA in the urine at the end of shift.
Mei
Yong
Y
Department of Occupational Health, College of Medicine, Wuhan University of Science and Technology, Wuhan 430065, China.
Song
Shi-Zhen
SZ
Chen
Si-Qi
SQ
Ye
Yu-Jie
YJ
Ye
Fang-Li
FL
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine; D000328:Adult; D001554:Benzene / Q000009:adverse effects* / Q000032:analysis; D001555:Benzene Derivatives / Q000652:urine*; D002681:China; D006801:Humans; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D020711:Threshold Limit Values; D055815:Young Adult
D001555:Benzene Derivatives; C053003:S-phenyl-N-acetylcysteine; D001554:Benzene; D000111:Acetylcysteine