Human Hair as Indicator for Mercury Exposure Evaluated by Cold Vapor Atomic Absorption Spectrometry

In this work, the determination of mercury (Hg) in human hair by cold vapor atomic absorption spectrometry (CVAAS) following acid mineralization using microwave digestion is presented. This work highlights the importance of human hair as an ideal indicator for the evaluation of mercury exposure. Human hair samples were obtained from 51 individuals: 19 individuals professionally exposed to Hg at odontological areas and 32 controls. Test samples were mineralized in high-pressure vessels inside the microwave oven, irradiated at 100% power during a 70-second heating cycle. Accuracy of the CVAAS method was tested by analyzing two reference materials, obtaining a mean relative error of 3.2% between the certified and experimental values. Recoveries for the test samples ranged from 100 to 104%. An average RSD of 1.70% was found for both the within- and between-run precision. Characteristic mass for Hg was determined to be 4.4 ng. The detection (3 sigma) and the quantification (10 sigma) limits were 0.07 and 0.24 mu g/L, respectively. The proposed method was used to establish the Hg levels in the hair of the population under study, finding mean concentrations (+/- 1 SD) of 2.05 +/- 2.12 and 1.86 +/- 1.90 mu g/g for exposed and control individuals, respectively. These values were not significantly different (p > 0.05). Human hair is a useful biological sample to determine the environmental contamination by Hg at odontological work areas. The CVAAS method for Hg was free from interferences, reliable and reproducible, constituting an excellent analytical tool for the evaluation of Hg levels in human hair.