Urinary bisphenol A exposure in relation to liver function abnormalities among U.S. adults: results from the National Health and Nutrition Examination Survey, 2003-2016

Background Bisphenol A (BPA) is an endocrine-disrupting chemical that has been linked with various health outcomes. However, few studies using nationally representative data have assessed the association between BPA exposure with liver function. In addition, whether behavior characteristics of smoking and alcohol use modify such association has been underexplored. Methods Using data from seven cycles of the National Health and Nutrition Examination Surveys (NHANES) among 11,750 adults from 2003 to 2016, we investigated the relationship between urinary BPA with liver function indicators. BPA concentration in urine was measured by using high performance liquid chromatography with atmospheric pressure chemical ionization–mass spectrometry. We estimated BPA concentration after controlling for creatinine and normalized the asymmetrical distribution using natural logarithmic transformation (ln-BPA/Cr). Eight liver function indicators in serum were examined. Multivariate linear regression models were performed to explore the association between urinary BPA with changes in liver indicators. Stratified analyses examined whether these associations varied by sex, age, smoking, or drinking. Findings Of the 11,750 participants (49.5% men), the mean age was 43.9 years. Per unit increment in ln-BPA/Cr was positively related to alkaline phosphotase (ALP) and total bilirubin (TBIL), while inversely with albumin (ALB). In quartile analysis, the highest BPA exposure was associated with higher aspartate aminotransferase (AST), ALP, and TBIL, while with decreased ALB (all Ptrend < 0.01). These associations for specific liver indicators (i.e., ALT, AST, Gamma-glutamyl transferase [GGT], and TBIL) were stronger in smokers and alcohol drinkers. Moreover, we found that BPA exposure with higher ALP in older adults (≥ 60 years) but no sex difference. Interpretation This nationally representative study suggested that urinary BPA was associated with elevated AST, ALP, TBIL, and inversely with ALB among U.S. adults. The associations were more evident in smokers and drinkers but no sex difference. Better understanding of the mechanisms is needed for improving liver and planetary health. Funding National Natural Science Foundation of China. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the National Natural Science Foundation of China (72204048). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the ethical review committee of the National Center for Health Statistics. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced are available online at NHANES website.