Use of natural history museum ungulate specimen hair as biomarkers for environmental trace element contamination

This study reports the first use of natural history museum ungulate specimens' (common fallow deer, bontebok, Arabian oryx, impala, Dall's sheep, water buffalo, and yak) hair as biomarkers for the determination of environmental trace element contamination and public exposure risk factor assessment. Morphological characteristics of the hair, like diameter and protein structure, were determined using optical microscopy and FTIR spectroscopy, respectively. The levels of thirty-nine (39) elements, sixteen (16) rare earth elements (REEs), and selected isotope ratios (⁵²Cr/⁵³Cr, ¹⁴⁴Nd/¹⁴⁶Nd, ¹⁴⁷Sm/¹⁴⁹Sm, ¹⁷³Yb/¹⁷²Yb, ²⁰⁶Pb/²⁰⁷Pb, and ²⁰⁶Pb/²⁰⁸Pb) in the hair samples were determined by ICP-MS analysis. A NIST 1643e standard reference material was analyzed for method validation to determine the accuracy of the developed elemental analysis method. The average hair diameter found in samples obtained from common fallow deer (193 ± 72 µm), bontebok (148 ± 48 µm), Arabian oryx (194 ± 40 µm), impala (88 ± 20 µm), Dall's sheep (240 ± 68 µm), water buffalo (139 ± 17 µm), and yak (139 ± 16 µm) were recorded. ²⁷Al (1642 ± 1551 mg·kg^-1), ⁴⁴Ca (506 ± 272 mg·kg^-1), ⁵⁶Fe (730 ± 1391 mg·kg^-1), ²⁴ Mg (108 ± 57 mg·kg^-1), ³⁹ K (720 ± 1591 mg·kg^-1), ²⁸Si (1125 ± 1163 mg·kg^-1), ²³Na (10,223 ± 9824 mg·kg^-1), and ⁶⁶Zn (33 ± 25 mg·kg^-1) have the highest concentrations detected in the hair samples. Potentially toxic elements and REEs have the lowest concentration in the hair samples. The detection of low concentrations of ⁷⁵As, ¹¹¹Cd, ⁵⁹Co, ⁵²Cr, ⁵³Cr, ⁶⁰Ni, Pb isotopes, and REEs in all hair samples suggests heavy metal contamination. The plausible sources of the detected elements in ungulate animal hair are likely due to dietary intake, anthropogenic activities, environmental contamination, specimens' preservation practices, or a combination of those sources. The figures of merit highlighted by a high correlation coefficient (R² ≥ 0.9990), low limit of detection (as low as 1.00 × 10^-7 mg·kg^-1 for ¹⁴⁰Ce), and high average percent recoveries (97.0 ± 11.5) of the NIST 1643e standard reference material analyses demonstrate the linearity, high sensitivity, and accuracy of the ICP-MS technique for elemental and isotopic analysis of hair samples.