Estimation of a safe level for occupational exposure to vinyl chloride using a benchmark dose method in central China.
OBJECTIVE
The aim of this study was to estimate a benchmark dose (BMD) for chromosome damage induced by vinyl chloride monomer (VCM) in VCM-exposed workers in central China and validate the published results in Shanghai.


METHODS
VCM-exposed workers who had been exposed to VCM for at least one year (n=463) and matched subjects not exposed to VCM or other toxins (n=273) were asked to participate in this study. Micronucleus (MN) frequency based on the cytokinesis-block micronucleus assay (CBMN) was used as a biomarker for chromosome damage induced by VCM exposure.


RESULTS
The MN frequency in the VCM-exposed workers was significantly higher than that in the control group, and multivariate Poisson regression suggested that gender, smoking status and VCM exposure were the significant factors influencing the risk of increased MN frequency. When subjects were further stratified according to gender and smoking status, the results showed that female VCM-exposed workers were more susceptible than the males to the risk of increased MN frequency. The MN frequency of smokers was significantly higher than that of nonsmokers in the control group. Our study also suggested that there was a strong dose-response relationship between VCM CED and the increased risk of MN frequency in the total group, males and females. The BMDL(10) was found to be 630.6, 670.2 and 273.7 mg-year for all VCM-exposed workers, males and females, respectively.


CONCLUSIONS
These results invite further scrutiny of the current VCM occupational exposure limits and warrant further study of the risk of VCM genotoxicity and carcinogenicity.
Department of Occupational Health and Toxicology, School of Public Health, Fudan University, China.
Jie
J
Jiao
Nan-nan
NN
Feng
Yong
Y
Li
Yuan
Y
Sun
Wu
W
Yao
Wei
W
Wang
Guang-hui
GH
Zhang
Shi-yi
SY
Sun
Hong-shan
HS
Tan
Qi
Q
Wang
Yiliang
Y
Zhu
Yongliang
Y
Li
Paul W
PW
Brandt-Rauf
Zhao-lin
ZL
Xia
D000328:Adult; D000367:Age Factors; D000395:Air Pollutants, Occupational / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D000428:Alcohol Drinking / Q000453:epidemiology; D015415:Biomarkers; D002681:China; D004249:DNA Damage / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D015162:Micronucleus Tests; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis* / Q000592:standards / Q000706:statistics & numerical data; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D014752:Vinyl Chloride / Q000032:analysis* / Q000592:standards / Q000633:toxicity
D000395:Air Pollutants, Occupational; D015415:Biomarkers; D014752:Vinyl Chloride