Human nails as a biomarker of arsenic exposure from well water in Inner Mongolia: comparing atomic fluorescence spectrometry and neutron activation analysis.

Arsenic (As) is found naturally in the geological strata within the Ba Men Region of Inner Mongolia, China. A study was conducted to compare the total As measurements from two analytical techniques: instrumental neutron activation analysis (INAA) and atomic fluorescence spectrometry (AFS), and to verify nails as an exposure biomarker in this population. In 1999, nail and water samples were collected in a pilot study. Fingernails and toenails were pooled from 32 participants and analysed for total As by both INAA and AFS. Mean nail As values were 14.8+/-2.4 and 19.4+/-2.8 microg g-1 (+/-SEM) for INAA and AFS, respectively. Results from these two methods were significantly correlated (r=0.93, p<0.0001). In 2000, a second study was conducted and INAA was used to measure total As in toenails from 314 Ba Men residents. Well water samples were collected from 121 households and analysed by AFS. A significant correlation was observed between toenail and well water As (r=0.84, p<0.0001). Based on the results, INAA was significantly correlated with AFS and proved to be a reliable measure of nail As levels. In this population, toenail samples are a useful internal As exposure biomarker from drinking water sources.