Monitoring of Environmental Metals in Human Blood: The Need for Data Validation

Human biomonitoring results can be used to evaluate prior metals' exposures but the data production must adhere to rigorous scientific standards including validation of the analytical method and calculation of the method's uncertainty. The whole procedure is often perceived as a difficult and time-consuming task. The aim of this paper was to in house validate a sector field inductively coupled plasma mass spectrometry-based method and to speed up the calculation of measurement's uncertainty in the monitoring of As, Be, Cd, Co, Cr, Hg, Ir, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Sb, Sn, Tl, U, V and W in human blood. The laboratory validation was organized so as to vary the most representative factors (operators, time, materials, instrumental settings, calibrations) that could affect the analytical data. Then, only those sources that significantly affected the final result were considered in the uncertainty estimate, simplifying so the process. Validation data in blood were: linearity, R2 > 0.9992 over two orders of concentration; detection limits between 0.0015 μg L-1 - 1.03 μg L-1; mean trueness on certified reference materials between 91.2%-109.6%; mean recovery on spikes ranging 92%-105%; repeatability from 3.0% to 6.3% and reproducibility from 3.8% to 9.2%. The expanded uncertainty budget derived from two sources (reproducibility and trueness/recovery) was between 11% and 26%. Applying the proposed procedure in future biomonitoring studies for metals' exposure will allow the production of analytical data of high quality and reliability. This is also crucial to correctly interpret the biomonitoring data with respect to statutory limits, reference limits and measures produced by other laboratories.