New Analytical Framework for Verification of Biomarkers of Exposure to Chemicals Combining Human Biomonitoring and...

Molecular epidemiology approaches in human biomonitoring are powerful tools that allow for verification of public exposure to chemical substances. Unfortunately, due to logistical difficulties and high cost, they tend to evaluate small study groups and as a result might not provide comprehensive large scale community-wide exposure data. Urban water fingerprinting provides a timely alternative to traditional approaches. It can revolutionize the human exposure studies as urban water represents collective community-wide exposure. Knowledge of characteristic biomarkers of exposure to specific chemicals is key to the successful application of water fingerprinting. This study aims to introduce a novel conceptual analytical framework for identification of biomarkers of public exposure to chemicals via combined human metabolism and urban water fingerprinting assay. This framework consists of the following steps: (1) in vitro HLM/S9 assay, (2) in vivo pooled urine assay, (3) in vivo wastewater fingerprinting assay, (4) analysis with HR-MSMS, (5) data processing, and (6) selection of biomarkers. The framework was applied and validated for PCMC (4-chloro-m-cresol), household derived antimicrobial agent with no known exposure and human metabolism data. Four new metabolites of PCMC (hydroxylated, sulfated/hydroxylated, sulfated PCMC, and glucuronidated PCMC) were identified using the in vitro HLM/S9 assay. But only one metabolite, sulfated PCMC, was confirmed in wastewater and in urine. Therefore, our study confirms that water fingerprinting is a promising tool for biomarker selection and that in vitro HLM/S9 studies alone, although informative, do not provide high accuracy results. Our work also confirms, for the first time, human internal exposure to PCMC.