the nail as a biomonitor of trace element status in golestan cohort study

background in the golestan cohort study that was launched to investigate the causes of esophageal cancer, a complete biospecimen bank was established for storage of collected blood, urine, hair, and nail samples. the objective of this study was to evaluate the feasibility of nail samples as a biomarker of selected trace elements status. methods thirty toenail samples were selected randomly from the participants of golestan cohort study (gcs). the samples were cleaned and analyzed for selenium, mercury, chromium, iron, zinc, and scandium by instrumental neutron activation analysis at the university of missouri research reactor center. pearson correlation coefficients were computed for selected trace elements concentration versus scandium concentration to assess terrestrial contamination. results the selenium, zinc, and mercury were not correlated with scandium, suggesting they were free from substantial contamination.  the high correlations of scandium with iron and chromium suggest that the iron and chromium levels may be compromised by terrestrial contamination.  the coefficients of variation for duplicate samples for selenium and zinc were 2.6% and 7.2%, respectively. conclusion the nail samples from golestan cohort study appears to be useable as a biomarker of selenium, zinc, and mercury and could be considered for use in future studies.