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Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth

Lookup NU author(s): Dr Thomas Shepherd, Dr Wendy Dirks, Professor Tanja Pless-Mulloli, Pamela Walton

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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 Pb-208/Pb-206, Pb-207/Pb-206 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 (<0.2 mu g Pb/g) with Pb-208/Pb-206 (mean +/- 2 sigma: 2.126-2.079) Pb-208/Pb-206 (mean +/- 2 sigma: 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 (>0.4 mu gPb/g) with Pb-208/Pb-206 (mean +/- 2 sigma: 2.145-2.117) Pb-208/Pb-206 (mean +/- 2 sigma: 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. (C) 2015 Elsevier Inc. All rights reserved.


Publication metadata

Author(s): Shepherd TJ, Dirks W, Roberts NMW, Patel JG, Hodgson S, Pless-Mulloli T, Walton P, Parrish RR

Publication type: Article

Publication status: Published

Journal: Environmental Research

Year: 2016

Volume: 146

Pages: 145-153

Print publication date: 01/04/2016

Online publication date: 02/01/2016

Acceptance date: 15/12/2015

ISSN (print): 0013-9351

ISSN (electronic): 1096-0953

Publisher: Elsevier

URL: http://dx.doi.org/10.1016/j.envres.2015.12.017

DOI: 10.1016/j.envres.2015.12.017


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