Rhinoceros Horn Mineral and Metal Concentrations Vary by Sample Location, Depth, and Color

Overview

Journal Sci Rep

Specialty Science

Date 2024 Jun 14

PMID 38877154

Authors

Terri L Roth

Sarah L Rebolloso

Elizabeth M Donelan

Louisa A Rispoli

John P Buchweitz

Affiliations

Soon will be listed here.

Abstract

Poaching is again driving rhinos to the brink of extinction due to the demand for rhino horn products consumed for cultural, medicinal, and social purposes. Paradoxically, the same horn for which rhinos are killed may contain valuable clues about the species' health. Analyses of horn composition could reveal such useful bioindicators while elucidating what people actually ingest when they consume horn derivatives. Our goals were to quantify minerals (including metals) in rhino horn and investigate sampling factors potentially impacting results. Horns (n = 22) obtained during necropsies of white (n = 3) and black (n = 13) zoo rhinos were sampled in several locations yielding 182 specimens for analysis. Initial data exposed environmental (soil) contamination in the horn's exterior layer, but also confirmed that deep (≥ 1 cm), contaminant-free samples contained measurable concentrations of numerous minerals (n = 18). Of the factors examined in deep samples, color-associated mineral differences were the most profound with dark samples higher in zinc, copper, lead, and barium (p < 0.05). Our data demonstrate that rhino horns contain both essential and potentially toxic minerals that could be relevant to rhino health status, but low concentrations make their human health benefits or risks unlikely following consumption.

References

Blacket M, Robin C, Good R, Lee S, Miller A . Universal primers for fluorescent labelling of PCR fragments--an efficient and cost-effective approach to genotyping by fluorescence. Mol Ecol Resour. 2012; 12(3):456-63. DOI: 10.1111/j.1755-0998.2011.03104.x. View

Schook M, Wildt D, Raghanti M, Wolfe B, Dennis P . Increased inflammation and decreased insulin sensitivity indicate metabolic disturbances in zoo-managed compared to free-ranging black rhinoceros (Diceros bicornis). Gen Comp Endocrinol. 2015; 217-218:10-9. DOI: 10.1016/j.ygcen.2015.05.003. View

Hieronymus T, Witmer L, Ridgely R . Structure of white rhinoceros (Ceratotherium simum) horn investigated by X-ray computed tomography and histology with implications for growth and external form. J Morphol. 2006; 267(10):1172-6. DOI: 10.1002/jmor.10465. View

But P, Lung L, Tam Y . Ethnopharmacology of rhinoceros horn. I: Antipyretic effects of rhinoceros horn and other animal horns. J Ethnopharmacol. 1990; 30(2):157-68. DOI: 10.1016/0378-8741(90)90005-e. View

Laburn H, Mitchell D . Extracts of rhinoceros horn are not antipyretic in rabbits. J Basic Clin Physiol Pharmacol. 1997; 8(1-2):1-11. DOI: 10.1515/jbcpp.1997.8.1-2.1. View

Wolowiec P, Michalak I, Chojnacka K, Mikulewicz M . Hair analysis in health assessment. Clin Chim Acta. 2013; 419:139-71. DOI: 10.1016/j.cca.2013.02.001. View

Sahin C, Pala C, Kaynar L, Torun Y, Cetin A, Kurnaz F . Measurement of hair iron concentration as a marker of body iron content. Biomed Rep. 2015; 3(3):383-387. PMC: 4467289. DOI: 10.3892/br.2015.419. View

Paglia D, Tsu I . Review of laboratory and necropsy evidence for iron storage disease acquired by browser rhinoceroses. J Zoo Wildl Med. 2012; 43(3 Suppl):S92-104. DOI: 10.1638/2011-0177.1. View

But P, Tam Y, Lung L . Ethnopharmacology of rhinoceros horn. II: Antipyretic effects of prescriptions containing rhinoceros horn or water buffalo horn. J Ethnopharmacol. 1991; 33(1-2):45-50. DOI: 10.1016/0378-8741(91)90159-b. View

10.

Jaramillo Ortiz S, Howsam M, van Aken E, Delanghe J, Boulanger E, Tessier F . Biomarkers of disease in human nails: a comprehensive review. Crit Rev Clin Lab Sci. 2021; 59(2):125-141. DOI: 10.1080/10408363.2021.1991882. View

11.

Wickre J, Folt C, Sturup S, Karagas M . Environmental exposure and fingernail analysis of arsenic and mercury in children and adults in a Nicaraguan gold mining community. Arch Environ Health. 2005; 59(8):400-9. DOI: 10.3200/AEOH.59.8.400-409. View

12.

Mehra R, Juneja M . Fingernails as biological indices of metal exposure. J Biosci. 2005; 30(2):253-7. DOI: 10.1007/BF02703706. View

13.

Pouillevet H, Soetart N, Boucher D, Wedlarski R, Jaillardon L . Inflammatory and oxidative status in European captive black rhinoceroses: A link with Iron Overload Disorder?. PLoS One. 2020; 15(8):e0231514. PMC: 7423059. DOI: 10.1371/journal.pone.0231514. View

14.

Goulle J, Saussereau E, Mahieu L, Bouige D, Groenwont S, Guerbet M . Application of inductively coupled plasma mass spectrometry multielement analysis in fingernail and toenail as a biomarker of metal exposure. J Anal Toxicol. 2009; 33(2):92-8. DOI: 10.1093/jat/33.2.92. View

15.

Roth T, Reinhart P, Kroll J . SERUM FERRITIN CONCENTRATION IS NOT A RELIABLE BIOMARKER OF IRON OVERLOAD DISORDER PROGRESSION OR HEMOCHROMATOSIS IN THE SUMATRAN RHINOCEROS (DICERORHINUS SUMATRENSIS). J Zoo Wildl Med. 2017; 48(3):645-658. DOI: 10.1638/2017-0010.1. View

16.

Olias P, Mundhenk L, Bothe M, Ochs A, Gruber A, Klopfleisch R . Iron overload syndrome in the black rhinoceros (Diceros bicornis): microscopical lesions and comparison with other rhinoceros species. J Comp Pathol. 2012; 147(4):542-9. DOI: 10.1016/j.jcpa.2012.07.005. View

17.

Miniaci M, Irace C, Capuozzo A, Piccolo M, Di Pascale A, Russo A . Cysteine Prevents the Reduction in Keratin Synthesis Induced by Iron Deficiency in Human Keratinocytes. J Cell Biochem. 2015; 117(2):402-12. DOI: 10.1002/jcb.25286. View

18.

Chaturvedi R, Banerjee S, Chattopadhyay P, Bhattacharjee C, Raul P, Borah K . High iron accumulation in hair and nail of people living in iron affected areas of Assam, India. Ecotoxicol Environ Saf. 2014; 110:216-20. DOI: 10.1016/j.ecoenv.2014.08.028. View

19.

Harper C, Ludwig A, Clarke A, Makgopela K, Yurchenko A, Guthrie A . Robust forensic matching of confiscated horns to individual poached African rhinoceros. Curr Biol. 2018; 28(1):R13-R14. DOI: 10.1016/j.cub.2017.11.005. View

20.

Liu R, Duan J, Wang M, Shang E, Guo J, Tang Y . Analysis of active components of rhinoceros, water buffalo and yak horns using two-dimensional electrophoresis and ethnopharmacological evaluation. J Sep Sci. 2011; 34(3):354-62. DOI: 10.1002/jssc.201000617. View