Advancing Lead Exposure Studies in Remote Settings: Method Development and Application of Lead Stable Isotope
Manasi Simhan1,2, Sean R Scott2, Martin M Shafer2
1Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI 53707, USA.
Abstract:
Background: Lead (Pb) exposure remains a major global health issue, and Pb stable isotope ratio analysis is a powerful tool for identifying potential exposure sources. However, traditional whole blood collection is difficult to implement in remote or resource-limited settings. We developed and validated a novel method for measuring Pb isotopic composition in dried blood spots (DBS) using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) and applied it in a pilot study of DBS collected from children in Suriname, South America. Methods: Method accuracy was evaluated by comparing isotopic ratios (208Pb/206Pb and 207Pb/206Pb) measured in laboratory-spiked DBS (15 µL of blood per DBS) with those from matched whole blood samples (1 mL) across a range of Pb concentrations (2.1-28.9 µg/dL). The method was then applied to DBS collected from 18 children, ages 6 months to 5 years, in Suriname. Potential local exposure sources, including soil, shotgun pellets, and cooking utensils, were also analyzed for lead isotopic composition and compared with DBS isotope ratios to assess source concordance. Results: DBS isotopic ratios accurately reflected whole blood values when Pb concentrations exceeded ~315 pg/punch (~2.1 µg/dL), with greater accuracy observed above 5 µg/dL. In the Suriname DBSs, blank-corrected 208Pb/206Pb ratios were consistent across regions (mean 2.12 ± 0.018; n = 15) and showed no significant geographic stratification (p = 0.11). DBS signatures (isotope ratios) most closely aligned with shotgun pellets and soil samples, whereas those from cooking utensils did not match DBS signatures. A positive correlation was observed between estimated blood total Pb and soil Pb concentrations (ρ = 0.60, p = 0.20). Conclusions: Overall, DBS provided reliable Pb isotopic ratio measurements above ~2-5 µg/dL, spanning the current CDC reference value of 3.5 µg/dL at which children's exposures warrant investigation. These findings support DBS as a minimally invasive, scalable tool for exposure source identification in environmental epidemiology, particularly in remote settings where traditional venipuncture is impractical. What this study adds: This study establishes the first validated method for high-precision lead (Pb) stable isotopic ratio analysis using dried blood spots (DBS). By implementing a sample blank correction, we demonstrate that DBS can accurately resolve isotopic signatures even at low blood lead concentrations. Applied in DBS collected in Suriname, the method successfully linked DBS signatures to local shotgun pellets and soils, illustrating a common exposure profile across diverse regions. This work expands the utility of DBS beyond simple screening, offering a minimally invasive, scalable tool for source attribution in global health research and environmental epidemiology in remote regions.
