Methyl <i>tert</i>-Butyl Ether May Be a Potential Environmental Pathogenic Factor for Nonalcoholic Fatty Liver Disease: Results from NHANES 2017–2020

Previous studies have shown that methyl <i>tert</i>-butyl ether (MTBE) could interfere with lipid metabolism. However, there is still a lack of epidemiological reports on the association between MTBE exposure and the risk of nonalcoholic fatty liver disease (NAFLD). In this study, a cross-sectional study was performed with data from the 2017-2020 cycles of the National Health and Nutrition Examination Survey (NHANES). The target population consisted of adults with reliable vibration controlled Transient elastography (VCTE) and blood MTBE concentration results. The hepatic steatosis and fibrosis were assessed by the values of the controlled attenuation parameter (CAP) and liver stiffness measurement (LSM), respectively. Generalized linear mixed model analysis was performed to evaluate the association between MTBE exposure and both steatosis and early liver fibrosis after adjustment for potential confounders. A total of 1303 subjects were enrolled and divided into NAFLD groups (CAP ≥ 248) and non-NAFLD groups (CAP < 248) based on the values of CAP in this study. Generalized linear mixed analysis suggested that blood MTBE concentration was positively associated with NAFLD risk in whole populations (OR: 2.153, 95% confidence interval [CI], 1.176-3.940) and female populations (OR: 11.019, 95% CI: 2.069-58.676). Blood MTBE concentration still showed an obvious positive correlation with the NAFLD risk after excluding factors such as diet and exercise in whole populations. Similarly, a positive correlation between blood MTBE concentration and liver fibrosis was also observed, although the results did not show significant statistical differences. In conclusion, our results indicate that MTBE exposure might be a potential important environmental pathogenic factor for NAFLD.