Genotoxicity in vinyl chloride-exposed workers and its implication for occupational exposure limit.

Background: Vinyl chloride monomer (VCM) is a colorless gas under room temperature and has been mostly used to produce polyvinyl chloride (PVC) since the 1970s. It is classified by the International Agency of Research on Cancer (IARC) as a known human carcinogen (Group 1). In this study, genetic damage in VCM workers was evaluated in relation to their occupational cumulative exposure to VCM.
Methods: Cytokinesis-block micronucleus assay was conducted in 229 VCM workers and 138 controls to detect chromosome damage in peripheral blood lymphocytes. The cumulative exposure dose (CED) of VCM was calculated based on the job type and duration of each worker and the workplace VCM concentration. Dose-response relationships between VCM CED and micronucleus frequency or chromosomal damage were evaluated, and benchmark doses (BMDs) estimated.
Results: Dose-response relationships between VCM CED and chromosomal damage were obtained. The 95% lower confidence bound of BMD of VCM CED was 2.86 mg/m(3) -year for both genders combined, leading to an estimated exposure limit of 0.072 mg/m(3) assuming a work life of 40 years.
Conclusions: VCM exposure may induce chromosomal damage at occupational exposure levels below the Chinese national occupational health standard. Further research is needed to better understand micronuclei as biomarker of VCM genotoxicity. Better dose-response assessment and BMD estimation are desirable in order to improve the quantification of occupational exposure limits for VCM with respect to non-cancer risk.
(Copyright © 2011 Wiley-Liss, Inc.)