Synchrotron X-ray absorption spectroscopy analysis of arsenic chemical speciation in human nail clippings

Abstract

Environmental context. Chronic ingestion of arsenic leads to its accumulation in keratinous tissues, which can represent a risk factor for developing cancer. We use synchrotron X-ray absorption spectroscopy to investigate chemical bonding of arsenic in the keratins from nail clippings of volunteers from areas in Atlantic Canada with low-to-moderate arsenic contamination of drinking water. The study helps our understanding of arsenic metabolism and its role in cancer development.Abstract. Drinking water aquifers in many areas of the world have naturally elevated levels of inorganic arsenic exceeding the World Health Organization limit. Arsenic concentrations in human nail clippings are commonly used as a biomarker of exposure to this toxic element. However, the chemical form of arsenic accumulated in nail tissues is not well determined. We employed synchrotron microprobe and bulk X-ray absorption spectroscopy techniques to analyse the concentration and chemical speciation of arsenic in the finger-and toenail clippings of volunteers living in the vicinity of Sackville, New Brunswick, Canada. This area is known to have low-to-moderately elevated levels of arsenic in ground water. Arsenic species in clippings were represented by three main groups, distinguished by the As-K near-edge X-ray absorption fine structure spectra: (1) As III type, which can be fitted as a mixture of As bound to thiols, and also to oxygen or methyl groups, with a small contribution from As V species, (2) As V type, best represented by fitting arsenate in aqueous solution and (3) The As III þ As V mixture type. The high proportion (%) of sulfur-bound arsenic species most likely corresponds to binding between arsenic (in its trivalent and, to a lesser extent, pentavalent forms) and cysteine residues in the sulfur-rich fraction of keratin and keratin-associated proteins. Further work is needed to explore whether these chemical species could be used as toxicity biomarkers of human exposure to elevated levels of As in drinking water.

Synchrotron radiation imaging analysis of neural damage in mouse soleus muscle

“…Therefore, the internal structure is freely analyzed in various axial directions. In addition, sample preparation can be simplified because the tissue-sectioning process is omitted 7,[25][26][27][28][29][30][31][32][33] . Because the superior spatial resolution facilitate 3D modeling and quantitative evaluation of microscale bio-samples, it can have shown enhanced identification of structures that are difficult to observe in conventional imaging or micro-CT imaging 33 .…”

“…Because the superior spatial resolution facilitate 3D modeling and quantitative evaluation of microscale bio-samples, it can have shown enhanced identification of structures that are difficult to observe in conventional imaging or micro-CT imaging 33 . Studies have been conducted using human breast tissue, nails, and hair, and rodent tissues, bones, blood vessels, and muscles using this technology 7,[25][26][27][28][29][30][31][32][33] .…”

Probing Trace Elements in Human Tissues with Synchrotron Radiation

“…Examples of XRF and XAS spectra are shown in the plots of Figure 3a,b, respectively. The spectra were taken from two different synchrotron-based studies: Gherase et al [30] and Ponomarenko et al [31] and targeted As microscopic distribution in human nails and the corresponding As speciation, respectively. Both studies used cross sections of human fingernail clippings from volunteers living in the vicinity of Sackville, New Brunswick, Canada.…”

“…Zn signal maps were also generated as part of the localization procedure for determining nail clipping boundaries. Some of these same nail clippings were used in a subsequent study to investigate As speciation [31]. XANES spectra from these clippings revealed As species to fall into three main groups: an As(III) type, fit as a mixture of As bound to thiols, and oxygen or methyl groups, with a small contribution from As(V) species; an As(V) type, best fit by arsenate in aqueous solution; and an As(III) plus As(V) mixture type.…”

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

“…The analysis of human ngernails and hair always reveals a wealth of information from their elemental composition. Although further work is needed, interesting results were collected by Ponomarenko et al, 364 who determined the concentration and chemical speciation of arsenic in the ngerand toenail clippings of volunteers living in the vicinity of Sackville, New Brunswick, Canada, as toxicity biomarkers of human exposure to elevated levels of As in drinking water. Arsenic species in clippings were represented by three main groups, distinguished by As-K NEXAFS spectra: (1) As III type, which could be tted as a mixture of As bound to thiols, and also to oxygen or methyl groups, with a small contribution from As V species, (2) As V type, best represented by tting arsenate in aqueous solution and (3) As III + As V mixture type.…”