Liver Fibrosis Associated with Potential Vinyl Chloride and Ethylene Dichloride Exposure from the Petrochemical Industry

Abstract

Background & Aims: The understanding of the relationship between exposure to carcinogenic vinyl chloride (VCM) and ethylene dichloride (EDC) and liver fibrosis is limited. This study aimed to investigate the associations between the urinary metabolite levels of VCM and EDC and the risk of fibrosis in residents living near a petrochemical complex. Approach & Results: Our study comprised 447 adult residents of two townships with questionnaire survey and health examination near the largest petrochemical complex in Taiwan. The urinary levels of thiodiglycolic acid (TdGA), the metabolite of VCM and EDC, were detected in study subjects. We utilized fibrosis-4 (FIB-4) as the liver fibrosis index. Adjusted generalized linear and logistic regression models were applied to evaluate the associations between those exposure and the risk of fibrosis. The subjects living in the closer township had significantly higher TdGA levels than those living in the more distant (269.6 ±200.7 vs. 199.2±164.7 μg/g creatinine). It showed that TdGA levels were 6.51 μg/g creatinine lower 1 km away from the emission source of the complex after adjusting for confounding factors. It demonstrated that the subjects with the highest TdGA levels (>343.3 μg/g creatinine) had a significantly higher risk of abnormal FIB-4 (OR=2.09; 95% CI: 1.17, 3.77), and those with higher TdGA levels (232.7 to 343.3 μg/g creatinine) had a marginally higher risk of abnormal FIB-4 (OR=1.65; 95% CI: 0.94, 2.90). Conclusion: The residents living closer to the VCM/PVC plant in the complex had higher urinary TdGA levels, which were significantly associated with the risk of fibrosis. This confirmed that the EDC and VCM potentially emitted from the petrochemical industry may have an impact on the liver health of nearby residents. Funding Statement: This research was funded by a grant from the Changhua County Public Health Bureau in Taiwan (grant number 1040723). The study was also funded by the Ministry of Science and Technology in Taiwan (grant number MOST 107-3017-F-002-003, MOST 108-3017-F-002-001) and Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education in Taiwan (grant numbers NTU-107L9003, NTU380 108L9003). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This study was approved by the Research Ethics Committee of the National Health Research Institutes in Taiwan, and written informed consent forms were signed by each subject.