The Use of Pb Isotope Ratios to Determine Environmental Sources of High Blood Pb Concentrations in Children: A Feasibility Study in Georgia

Abstract

The incidence of lead (Pb) poisoning in children in Georgia has been identified as a major health concern, with a recent national survey identifying that 41% of children aged 2-7 years had blood lead concentrations (BLCs) greater than the blood lead reference value (BLRV) of ≥5 µg dL^-1. This study collected samples of blood, spices, paint, soil, dust, flour, tea, toys, milk, and water from 36 households in Georgia where a child had previously been identified as having a BLC > BLRV. The Pb concentrations of these samples were determined and compared to Georgian reference values. Samples from 3 households were analysed for their Pb isotope composition. The Pb isotope composition of the environmental and blood samples were compared to identify the most likely source(s) of Pb exposure. This approach identified that some spice and dust samples were the likely sources of Pb in the blood in these cases. Importantly, some soil, paint, and dust sources with high Pb concentrations could be discounted as contributing to blood Pb based on their distinct isotope composition. The data presented demonstrate the significant contribution that Pb surveillance and Pb isotope ratio analyses can make to managing Pb exposure in regions where high BLCs are identified.

Keywords: Georgia; blood lead concentration; children; dust; environmental tracing; lead isotope ratio; lead surveillance; paint; soil; spices.

Figure 1

Map of Georgia showing its borders with neighbouring countries and the regions within Georgia.

Figure 2

Summary of the criteria used to identify potential candidates based on data from the MICS.

Figure 3

Box and whisker plot of the Pb concentrations for all samples. Where applicable, Georgian reference values are indicated by a horizontal red-dashed line.

Figure 4

Box and whisker plot of the Pb concentration for each spice category analysed in this study. The plot shows the mean, median, and interquartile range of the data, and any outlier samples. The Georgian reference value for Pb in spice (5 mg kg⁻¹) is indicated by the red-dashed line.

Figure 5

Lead isotope plots of the blood and environmental samples collected from each of the three households. Insets show a zoomed-in area of the plots focused around the corresponding blood data and are indicated by the rectangles outlined by a dashed line in the main plot. Scaled points are also included for the spice, dust, and soil samples to give an indication of the total Pb concentration for the corresponding sample. (A)—Isotope ratio data from Household A. (B)—Isotope ratio data from Household B. (C)—Isotope ratio data from Household C.