Longitudinal isotope ratio variations in human hair and nails

Katerina Rodiouchkina; Ilia Rodushkin; Steven Goderis; Frank Vanhaecke

doi:10.1016/j.scitotenv.2021.152059

Longitudinal isotope ratio variations in human hair and nails

Sci Total Environ. 2022 Feb 20:808:152059. doi: 10.1016/j.scitotenv.2021.152059. Epub 2021 Dec 1.

Authors

Katerina Rodiouchkina¹, Ilia Rodushkin², Steven Goderis³, Frank Vanhaecke⁴

Affiliations

¹ Ghent University, Department of Chemistry, Atomic and Mass Spectrometry (A&MS) research group, Campus Sterre, Krijgslaan 281 - S12, 9000 Ghent, Belgium.
² ALS Scandinavia AB, ALS Laboratory Group, Aurorum 10, S-977 75 Luleå, Sweden.
³ Vrije Universiteit Brussel, Department of Chemistry, Analytical, Environmental and Geo-Chemistry (AMGC) research group, Pleinlaan 2, 1050 Brussels, Belgium.
⁴ Ghent University, Department of Chemistry, Atomic and Mass Spectrometry (A&MS) research group, Campus Sterre, Krijgslaan 281 - S12, 9000 Ghent, Belgium. Electronic address: frank.vanhaecke@ugent.be.

PMID: 34863743
DOI: 10.1016/j.scitotenv.2021.152059

Abstract

Due to the straightforward and non-invasive sampling, ease of transport and long-term storage and access to time-resolved information, determination of element concentrations and isotope ratios in hair and nails finds increasing use. Multi-isotopic information preserved in keratinous tissues allows one to reveal dietary, physiological and environmental influences, but progress in this area is still limited by complicated and time-consuming analytical procedures and challenges in accuracy assessment. In this study, longitudinal distributions of δ³⁴S, ⁸⁷Sr/⁸⁶Sr, ^207,208Pb/²⁰⁶Pb, δ⁶⁶Zn, δ⁵⁶Fe, δ⁶⁵Cu, δ²⁶Mg, and δ¹¹⁴Cd were obtained for hair and nails collected from nine subjects with different age, biological sex, diet and/or place of residence. For S and Zn, the distribution along hair strands revealed a trend towards a heavier isotopic signature from the proximal to the distal end, with a maximum difference within the hair of a single subject of 1.2‰ (Δ³⁴S) and 0.4‰ (Δ⁶⁶Zn). For Fe, Cu, Mg and Cd, a shift towards either a lighter (Cu) or heavier (Fe, Mg and Cd) isotopic composition is accompanied by increasing concentration towards the distal hair end, indicating possible isotope fractionation during deposition or external contamination with a different isotopic composition. Pb and Sr isotope ratios are relatively stable throughout the hair strands despite notable concentration increases towards the distal end, likely reflecting external contamination. The isotopic composition of Sr points to tap water as a probable main source, explaining the relative stability of the ratio for individuals from the same geographical location. For Pb, isotopic compositions suggest tap water and/or indoor dust as possible sources. Similar δ³⁴S, ⁸⁷Sr/⁸⁶Sr, ^207,208Pb/²⁰⁶Pb, δ⁶⁶Zn, δ⁵⁶Fe, and δ⁶⁵Cu observed for hair, fingernails and toenails sampled from the same individual suggest that keratinous tissues are conservative receivers of internal and external inputs and can be used complementary. Seasonal variation in δ³⁴S, ^207,208Pb/²⁰⁶Pb, and δ⁶⁵Cu was observed for fingernails.

Keywords: Fractionation; Hair; Isotope ratio; Multi-collector ICP-Mass Spectrometry (MC-ICP-MS); Nails; Trace element concentration.

MeSH terms

Dust
Hair
Humans
Isotopes*
Keratins
Nails*

Substances

Dust
Isotopes
Keratins