SUMMARY Non-alcohol fatty liver disease (NAFLD) is characterized by an accumulation of fat (steatosis) in the liver in the absence of significant alcohol consumption. It represents a leading cause of chronic liver disease in the U.S. and is believed to play a key role in metabolic disorders. Recent evidence suggests that exposure to environmental pollutants including metals and metalloids may play a role in the development of NAFLD and other metabolic outcomes. However, studies examining the association between metal exposures and liver injury in a general population are scant and most evidence is cross-sectional. In this diversity supplement, we will leverage data from two existing cohorts: the VapeScan cohort (parent R01) and the Multi-Ethnic Study of Atherosclerosis and Arsenic study (R01ES028758) to examine associations of metal exposure with metabolic profiles and hepatic steatosis in young adults (VapeScan) and adult (MESA) populations. We hypothesize that metal exposures (e.g., arsenic, cadmium, manganese), including mixtures, are associated with 1) higher levels of metabolic markers and 2) higher hepatic fat. Our specific aims are: (1) Determine the association of metals (alone and as a mixture) with metabolic factors in diverse young adults from New York City. We will use data from the Vape Scan cohort to examine the associations of metals with measures of metabolic outcomes that are risk factors of NAFLD measured in fasting serum samples (lipids, glucose) and during the examination (systolic and diastolic blood pressure and body mass index) at the baseline visit and two follow-visits over a 1.5 year period. (2) Determine the association of metal mixtures with subclinical measures of liver disease. We will use data from 6,618 participants in the MESA, a cohort study of White, Black, Hispanic, and Chinese American adults recruited from 6 U.S. cities to examine the association of metal exposure with hepatic steatosis measured by computed tomography (CT) as part of the MESA examination. This project will provide novel evidence on the role of toxic metals and the mixtures on metabolic outcomes, including liver disease, which can contribute to target modifiable disease factors of these conditions. Moreover, by providing advanced skills, training and research opportunities to an MPH student (4+1 program) with focus in Environmental and Molecular Epidemiology, this project will enhance diversity in our research team at Columbia University and down the road in the field of environmental health sciences.