Evaluation of dried blood spots approach to measure blood lead concentrations in low-level exposure scenarios

Abstract

Exposure to lead (Pb) is typically measured in whole venous blood, which is costly, invasive, and requires rapid transport of fragile samples for testing—all significant challenges for population-level testing. The dried blood spot (DBS) method offers the promise of a more sustainable, environmentally friendly method to measure Pb exposures. This study compares low-level blood Pb concentrations (BLLs) obtained from HemaSpot™ HF devices to those from whole venous blood. DBS shows promise as a lower-cost, minimally invasive, and easily transported method. As opposed to the temperature-controlled storage and transportation requirements associated with liquid blood samples, DBS method uses 2 drops of whole blood (approximately 100 µL) deposited on an absorbent paper in the device for subsequent digestion and analysis by inductively coupled plasma mass spectrometry. Blood spots were collected from 130 children aged 6–8 years participating in the Salud Ambiental Montevideo research cohort in Montevideo, Uruguay. A method limit of detection of 0.0050 µg/dL and a method limit of quantification of 0.020 µg/dL was achieved. The BLLs determined using the DBS method ranged from 0.020 to 1.5 µg/dL; by comparison, the BLLs determined via a conventional method ranged from 0.060 to 0.88 µg/dL. The Pearson correlation between the DBS and conventional methods indicated weak concordance (r = 0.103, p = 0.245). Moreover, low kappa statistics further indicated limited agreement between the two methods. These results suggest that, despite sustainability advantages for collection and storage, DBS analysis in scenarios of low-level Pb exposure will not yield valid results without further methodological improvements.