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Sci Total Environ. 2020 Jan 15;700:134519. doi: 10.1016/j.scitotenv.2019.134519. Epub 2019 Nov 4.

A comparison of blood and toenails as biomarkers of children's exposure to lead and their correlation with cognitive function.

Author information

1
Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA.
2
Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA; Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
3
Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA; Division of General and Community Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
4
Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Environmental Health Sciences, School of Public Health, The University of Albany, Rennselaer, NY, USA.
5
Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA; Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
6
Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA; Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, USA. Electronic address: jason.unrine@uky.edu.

Abstract

This study sought to compare lead (Pb) concentrations in toenails and blood and to investigate the association of each biomarker with children's cognitive function. Toenails and whole blood samples were collected from 224 twelve-year-old children, and their full-scale intelligence quotient (FSIQ) was assessed using the Wechsler Intelligence Scale for Children-4th edition. Inductively coupled plasma-mass spectrometry was used to determine blood (BPb) and toenail (TPb) Pb concentrations. Log BPb and Log TPb were significantly correlated (r2 = 0.49, p < 0.001). In unadjusted analyses, both log-transformed BPb and TPb were significantly associated with decreased FSIQ, but BPb accounted for approximately quadruple the FSIQ scores' variability than log-transformed TPb (model R2 = 0.12 and R2 = 0.03, respectively). After adjusting for neighborhood deprivation, caregiver intelligence (assessed with the Wechsler Abbreviated Scale of Intelligence-2nd edition), and child BMI, BPb remained significantly associated with decreased FSIQ, while TPb did not (p = 0.16). These results suggest that while concentrations of Pb in blood and toenails are correlated, TPb does not predict cognitive outcomes at these exposure levels. With caution and in conjunction with BPb, TPb may be used as a population-based biomarker of Pb exposure.

KEYWORDS:

Biomarker; Children’s exposure; Lead; Toenail

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