Relationship between exposure to metalworking fluids and nonalcoholic fatty liver disease

Objective The relationship between metalworking fluids (MWFs) and nonalcoholic fatty liver disease (NAFLD) has not been previously explored. We aim to investigate the relationship between occupational exposure to MWFs and the prevalence of NAFLD and to determine the cumulative exposure threshold per day. Methods In 2020, 2079 employees were selected randomly from one computer numerical control machining factory in Wuxi for a questionnaire survey, and occupational health examinations were conducted at the affiliated branch of Wuxi Eighth People's Hospital. MWF samples were collected within the factory using the National Institute for Occupational Safety and Health (NIOSH) 5524 method. NAFLD was defined as having a hepatic steatosis index (HSI) ≥ 36 without significant alcohol consumption. The relationship between NAFLD and MWFs was analyzed using logistic regression, and the daily exposure threshold was calculated using R software. Results MWF exposure was found to be a risk factor for NAFLD in exposed workers compared to the non-exposed group. The OR for NAFLD in workers exposed to MWFs compared to controls was 1.42 (95% CI: 1.04–1.95). An increased risk of NAFLD was shown to be associated with an increasing dose. The daily exposure dose threshold to MWFs was found to be 6.54 mg/m 3 (OR = 2.09, 95% CI: 1.24–3.52). Conclusion An association between occupational exposure to MWFs and NAFLD was found. As the concentration of exposure rose, the prevalence of NAFLD was also escalated.