Prevalence and risk factors of chronic liver disease among oil refinery workers

Objectives: The objective of this study was to determine the prevalence and major risk factors of chronic liver diseases among workers in an oil refinery and research factory with ultrasonography as an assessment tool. Methods: After a walk-through survey in the factory, workers were classified into exposed and non-exposed groups. Regular health screening data for the past four years were collected and all 700 workers were asked to fill out a questionnaire about their life style. A total of 345 workers voluntarily participated in the study, and 326 of them had abdominal ultrasonography. Results: Fatty liver disease (FLD) was found to be the most common problem (27.9%), followed by hepatitis virus infection (HBsAg positive rate: 18.0%, anti-HCV positive rate: 2.6%). The major causes of persistent alanine aminotransferase (ALT) increase were FLD and hepatitis virus infection. Obesity was the most important determinant of FLD and hepatitis virus infection was that of parenchymal liver disease (PLD). Modeling by multiple logistic regression model demonstrated that exposure to petroleum distillates or other chemicals in this factory was not associated with FLD, PLD or persistent ALT increase even in workers employed for more than twenty years. Obesity and virus infection did not show a synergistic hepatotoxic effect on solvent exposure probably due to a low level of exposure. Conclusions: Fatty liver and chronic hepatitis 6 infection were the major chronic liver diseases in oil-refinery workers in Taiwan, where exposure to hepatotoxic solvents was low.