title: Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth.
abstract: We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that laser ablation Pb isotope analysis of deciduous teeth, when carried out in conjunction with histological analysis, permits a reconstruction of the timing, duration and source of exposure to Pb during early childhood. With further development, this approach has the potential to study larger cohorts and appraise environments where the levels of exposure to Pb are much higher.
authors.affiliation: Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK; British Geological Survey, Keyworth, Nottingham, UK.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Shepherd
authors.affiliation: Department of Anthropology, Durham University, Durham, UK.
authors.forename: Wendy
authors.initials: W
authors.lastname: Dirks
authors.affiliation: NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham, UK.
authors.forename: Nick M W
authors.initials: NM
authors.lastname: Roberts
authors.affiliation: Leeds Dental Institute, University Leeds, Leeds, UK.
authors.forename: Jaiminkumar G
authors.initials: JG
authors.lastname: Patel
authors.affiliation: MRC-PHE Centre for Environment and Health, Department of Epidemiology and Biostatistics, Imperial College London, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Hodgson
authors.affiliation: Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Tanja
authors.initials: T
authors.lastname: Pless-Mulloli
authors.affiliation: Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Pamela
authors.initials: P
authors.lastname: Walton
authors.affiliation: British Geological Survey, Keyworth, Nottingham, UK.
authors.forename: Randall R
authors.initials: RR
authors.lastname: Parrish
mesh_terms: D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003743:Dental Enamel / Q000737:chemistry*; D003804:Dentin / Q000737:chemistry*; D004739:England; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005260:Female; D005333:Fetus / Q000378:metabolism; D006801:Humans; D007554:Isotopes / Q000378:metabolism; D007854:Lead / Q000378:metabolism*; D013058:Mass Spectrometry; D010865:Pilot Projects; D011247:Pregnancy; D014094:Tooth, Deciduous / Q000737:chemistry*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D007554:Isotopes; D007854:Lead
keywords: Biomarkers; Childhood exposure; Deciduous teeth; Laser ablation ICP-MS; Lead isotopes; Source apportionment