Comparison and Agreement of Toxic and Essential Elements Between Venous and Capillary Whole Blood

For practical and ethical reasons, there is an interest in the use of capillary blood as an alternative to classical human biomonitoring methods that use venipuncture. However, with the exception of Pb, few elements have been studied in detail to understand potential differences in measures between capillary and venous blood. To increase our understanding of the agreement in concentrations of select toxic metal(loid)s and essential minerals in venous and capillary whole blood. Concentrations of As, Pb, Cd, Mn, Cu, Fe, and Se were measured with Inductively Coupled Plasma-Mass Spectrometry in venous and capillary whole blood samples obtained from 49 healthy adult members of the McGill University community in 2016. Measured concentrations of all elements were similar to values reported in background populations. There were strong correlations (i.e., p < 0.001) in measures taken for all these elements between capillary and venous blood. Using Bland-Altman, a deeper investigation of the agreement between the measures found relatively good agreement for blood As, Pb, Cu, and Fe. For blood Cd, Mn, and Se, the agreement between the measures taken in capillary and venous blood was less consistent, though more research is needed to determine if the method can be improved and/or if there are real differences. For the seven elements under investigation, there was relatively good correlation and agreement in measures taken between capillary and venous blood from the same individual. Further research is needed to confirm these findings (particularly from more diverse population groups), expand the number of elements analyzed, and explore the utility of capillary sampling in biomonitoring programs that take samples using traditional venipuncture methods.