Retrospective cohort study protocol to determine prenatal and infant lead exposure using novel dentition analysis in Flint, Michigan: Flint Tooth FAIRY (Flint assessment of in-utero and at-risk young).

Abstract

The Flint water crisis (FWC) exposed thousands of in-utero fetuses and infants to lead-contaminated drinking water, yet the full extent of exposure remains unknown due to limitations in traditional biomonitoring methods. While blood lead levels provide momentary snapshots of exposure, novel dentition analysis using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) enables detailed reconstruction of prenatal and early-life exposure through deciduous teeth ("baby" teeth). This protocol describes a retrospective study investigating prenatal and early life exposure to lead during the FWC using shed deciduous teeth. The Flint Tooth Flint assessment of in-utero and at-risk young study aims to recruit approximately 364 children born in Flint, Michigan, between 1 January 2011 and 31 December 2015, through the Flint Registry. Recruitment began in July 2021 and the expected study period is through December 2026. Caregivers will complete questionnaires detailing residential history and infant feeding practices. Naturally shed deciduous teeth will be analysed via LA-ICP-MS to measure lead and other plumbing-related metal concentrations. Using dental growth patterns, measurements will be assigned temporal points to construct weekly exposure profiles. Statistical analyses will assess associations between tooth metal concentrations and potential risk factors, including residential water service line material, household water consumption patterns, infant feeding practices and residential history. This study focuses on exposure reconstruction only and does not include child health outcome assessment. This study was approved by the Biomedical and Health Institutional Review Board (study ID STUDY00003045). Results will be disseminated through peer-reviewed publications and presentations to stakeholders. Individual exposure profiles will be shared with families using the Tooth Lead Report-Back Toolkit, created by researchers at The Institute for Climate Change, Environmental Health and Exposomic Research at the Icahn School of Medicine at Mount Sinai.