LC-HRMS metabolomics for chemical exposome analysis

The term exposome describes the totality of all chemical exposures of an individual in a lifetime. Measuring the chemical exposome is complex, diverge and dynamic in nature. Therefore, novel analytical approaches based on metabolomics technology and using liquid chromatography high-resolution mass spectrometry (LC-HRMS) has been gaining attention for analyzing foreign chemical substances in human samples such as urine and blood. Metabolomics is the large-scale study of small molecules (metabolites) in a biological system. Pesticides, veterinary drugs and mycotoxins are molecules foreign to the human body that frequently enter the food chain and exert potential short-and long-term toxic effects to human health including cancer, reproductivedisorders, endocrine disruptors, antimicrobial resistance and immunodeficiency disease. We are typically exposed to cocktails of these potentially toxic molecules at low levels through our food and environment. Therefore, evaluating their exposure to understand the human chemical exposome is extremely important, yet often unexplored. There is no comprehensive analytical workflow for chemical exposome analysis including the classes pesticides, veterinary drugs and mycotoxins in human samples. The aim of the project is to establish an advanced assay using mass spectrometry to investigate these chemicals in human bio-fluids (plasma, urine and breast milk) with the help of computational tools. The established tool will be applied to explore a potential association of the assessed xenobiotic exposures with liver cancer risk using samples from Bangladesh. The project will produce new research findings and knowledge that can be useful in the areas of analytical chemistry, food safety and environmental health. The project will further show future research directions for other, less investigated but potentially toxic chemicals, within the exposome framework and produce more comprehensive knowledge on how external chemical exposures can be linked to biomarkers discovery and human diseases. The project will be coordinated by Lise Meitner-Fellow Md Zakir Hossain under the supervision of Prof. Benedikt Warth at the Global Exposomics and Biomonitoring Laboratory, Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Austria and in collaboration with two partner institutions in Bangladesh.

Humans are exposed to a cocktail of environmental exposures throughout their lifetime. The chemical exposome encompasses the totality of all these chemical exposures but characterizing the chemical exposome is a challenging task and requires sensitive human biomonitoring methods using advanced mass spectrometry and data analysis tools to investigate wide coverage of potential chemical exposures in human biofluids. Evaluating chemical exposures is extremely important to understand potential exposures and health impacts, yet often unexplored. In the research project "LC-MS metabolomics for chemical exposome analysis", we developed and established multi-analyte human biomonitoring methods for 13 diverse chemical xenobiotic classes incorporating more than 40 veterinary drugs (VDs) and pesticides. This expanded human biomonitoring (HBM) analytical method/workflow utilizes a liquid chromatography (LC) system coupled with a mass spectrometer (MS/MS) and a reverse-phase column from efficient chromatographic separation. Mass spectrometric parameters such as precursor ion (Q1), product ion (Q3), DP (declustering potential), CE (collision energy) were optimized and successfully detect more than 120 analyzed chemical xenobiotics in urine in a single analytical run. The method's specificity, matrix effects, linearity, and sensitivity (limit of quantification and detection) were estimated. The established workflow was then successfully applied to analyze 445 urine samples from a cohort of pregnant Bangladeshi women to explore real-life chemical exposome patterns. We observed that 50% of the screened analytes were detected in at least one urine sample with a median detection frequency of 17%. This cohort has a large population size and the potential to assess the exposure risk and additionally explain regional chemical exposome. The project resulted in a) a reliable, scalable, and sensitive HBM workflow to simultaneously detect over 120 diverse exposure chemicals including veterinary drugs, pesticides and mycotoxins in urine and b) the application of established HBM workflow to exposure chemical diversity in large-scale population cohort from Bangladesh through collaboration with international research partners to explore the potential association between studies chemical classes and associated chronic causes of disease. As a long-term perspective, new insights gained through this project will contribute to analytical chemistry, food safety, and environmental/occupational health as well as show the future directions for exploring less-studied but potentially toxic chemicals within the exposome framework and their association with biomarker discovery and chronic human diseases.