Speciation of arsenic in human nail and hair from arsenic-affected area by HPLC-inductively coupled argon plasma mass spectrometry.

Nail and hair are rich in fibrous proteins, i.e., alpha-keratins that contain abundant cysteine residues (up to 22% in nail and 10-14% in hair). Although they are metabolically dead materials in the epidermis, the roots are highly influenced by the health status of the living beings and their analyses are used as a tool to monitor occupational and environmental exposure to toxic elements. The aims of the present study are to speciate arsenicals in human nail and hair and also to judge whether they should be used as a biomarker to arsenic (As) exposure and/or toxicity. All human fingernail and hair samples (n = 47) were collected from the As-affected area of West Bengal, India. Speciation of arsenicals in water extracts of fingernails and hair at 90 degrees C was carried out by HPLC-inductively coupled argon plasma mass spectrometer (ICP MS). Fingernails contained iAs(III) (58.6%), iAs(V) (21.5), MMA(V) (7.7), DMA(III) (9.2), and DMA(V) (3.0), and hair contained iAs(III) (60.9%), iAs(V) (33.2), MMA(V) (2.2), and DMA(V) (3.6). Fingernails contained DMA(III), but hair did not. The higher percentage of iAs(III) both in fingernails and hair than that of iAs(V) suggests more affinity of iAs(III) to keratin. Although all arsenicals in fingernails and hair correlate to As exposure positively, As speciation in fingernails seems to be more correlated with arsenism than that in hair. Exogenous contamination is a confounding factor for hair to consider it as a biomarker, whereas this is mostly absent in fingernails, which recommends it to be a better biomarker to arsenic exposure. DMA(III) content in fingernails and DMA(V) contents in both fingernails and hair could be the biomarker to As exposure.