Urinary thiodiglycolic acid is associated with increased risk of non-alcoholic fatty liver disease in children living near a petrochemical complex.

Chih-Wen Wang, Hung-Yi Chuang, Kai-Wei Liao, Ming-Lung Yu, Chia-Yen Dai, Wan-Ting Chang, Cheng-Hsan Tsai, Hung-Che Chiang, Po-Chin Huang

Journal: Environment international 2020;131():104978

PMID: 31325714

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Abstract

BACKGROUND

Occupational and experimental studies have revealed that high vinyl chloride monomer (VCM) exposure is associated with non-alcoholic fatty liver disease (NAFLD). Epidemiological study reported that children living near a petrochemical complex have elevated exposure levels of urinary thiodiglycolic acid (TDGA), a potential VCM biomarker. However, no studies on the association of urinary TDGA exposure with NAFLD in children are available.

AIM

To assess the association of pediatric NAFLD with urinary TDGA exposure in school-aged children living near a petrochemical complex.

MATERIALS AND METHODS

In total, 261 school-aged children (aged 6-13 years) living near a petrochemical complex were recruited during October 2013 to September 2014. First morning spot urine was sampled for analyzing urinary TDGA through liquid chromatography-tandem mass spectrometry. Ultrasonography and serum alanine aminotransferase (ALT) were examined in each participant. NAFLD was diagnosed as recommended by the North American and European Society of Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN and ESPGHAN). Risk for NAFLD with urinary TDGA exposure in children was evaluated using a multivariate logistic regression model.

RESULTS

The percentage of children with NAFLD and NAFLD were 9.6% and 11.5%, respectively. Median levels (μg/g creatinine) of urinary TDGA of children with NAFLD (vs non-NAFLD) and NAFLD (vs non-NAFLD) were 118.0 (vs 96.6) and 113.1 (vs 96.5), respectively. Participants in the highest urinary TDGA quartile (Q4: ≥160.0 μg/g creatinine) had a significantly increased risk (odds ratio [OR] = 4.95; 95% confidence interval [CI] = 1.15-21.38; P = 0.032) and dose-response trend (P = 0.045) for NAFLD compared with those in the lowest urinary TDGA quartile (Q1: <35.4 μg/g creatinine) after adjustment for age, gender, BMI, triglycerides, HOMA-IR and distance of elementary schools from the petrochemical complex. Participants in the Q4 had borderline significantly increased risk (OR = 3.45; 95% CI = 0.89-13.42; P = 0.074) correlated with NAFLD compared with those in the Q1 after adjustment for confounders.

CONCLUSION

Our findings support the hypothesis that children exposed to higher urinary TDGA levels significantly increased pediatric NAFLD risk. Serum ALT levels can be a useful predictor for screening children's NAFLD in field studies. Large and longitudinal studies are warranted to elucidate the association.

Address: National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan; Hepatobiliary Division, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Ph.D. Program in Environmental and Occupational Medicine, Kaohsiung Medical University and National Health Research Institutes, Taiwan.; Department of Public Health, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Occupational and Environmental Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.; National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan.; Hepatobiliary Division, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.; Department of Pediatrics, National Taiwan University Hospital Yunlin Branch, Yunlin, Taiwan.; College of Medicine, China Medical University, Taichung, Taiwan.; National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Safety, Health and Environmental Engineering, National United University, Miaoli, Taiwan. Electronic address: [email protected].

DOI: 10.1016/j.envint.2019.104978

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MeSH Terms: Adolescent, Alanine Transaminase, Biomarkers, Child, Environmental Exposure, Female, Humans, Male, Non-alcoholic Fatty Liver Disease, Odds Ratio, Oil and Gas Industry, Risk Factors, Thioglycolates, Vinyl Chloride