Occupational Exposure Assessment Of Vinyl Chloride Monomer Exposed Workers

Vinyl chloride monomer(VCM) is an important raw chemical material,mainly used to polymerize to polyvinyl chloride.Long term and higher concentration exposure to VCM can result in typical syndrome known as 'vinyl chloride disease'. VCM has been proved to be a multi-organ and multi-system carcinogen in human, and VCM occupational poisoning is one of the legal occupational disease in China. Chinese government attaches great importance to control the concentrations of VCM in workplace and to reduce the occupational hazard of VCM.Current occupational VCM exposure limit of China is Permissible Concentration-Time Weighted Average (PC-TWA) 10mg/m³.Monitoring and testing methods of VCM in occupational health standards of China recommend the "Direct Injection-Gas Chromatography" and "thermal desorption-gas chromatography," to measure the VCM concentration in workplace. Because of the shortage of sample storage time or equipment limitations,the two methods make a number of application difficulties in some research.VCM collected by active charcoal was desorbed by carbon disulfide,then the VCM in CS₂ was analyzed by gas chromatography.Limit of detection,relative standard deviation and average desorption efficiency of carbon disulfide of this method were all accordant to the Chinese guideline of the method for determination of toxic substances in workplace air.This study compartmentalized the exposure groups according to the concept of Similar Exposure Group(SEG) and classification of methods,after field investigation in a VCM production plant in Shanghai and analyzed its historical monitoring data. Personal sampling results showed that average VCM daily cumulative exposure to different SEG is between 0.724mg to 6.238mg(to male workers).The calculated VCM exposure Time Weighted Average(TWA) concentration on personal sampling data and area sampling data are inconsistent,the latter is higher. Although area sampling data may make some systematic errors by using to estimate individual exposure level of workers,it is a good interpretation and complement to personal sampling.Exposure assessment should adopt personal sampling,and area sampling at the same time as a comparison.Historical monitoring data can also provide valuable reference.Classification of exposure groups,the choice of sampling method,sample size and calculation method may affect the quality of exposure assessment.