Lead (Pb) contamination in low- and middle-income countries: exposures, outcomes and mitigation

Human lead exposure contributes to a number of adverse health and social outcomes. The most significant historical source of exposure was the addition to tetraethyl lead (TEL) to petrol throughout the 20th century, which resulted in widespread contamination of human and natural environments. By the early 21st century nearly all countries had taken steps to phase out the use of TEL. Subsequent biological assessments of humans have universally shown significant and rapid declines in lead concentrations, typically measured in blood. In high income countries, the declines were particularly substantial. In the United States, for example, mean blood lead levels (BLLs) are currently < 1 μg/dL compared to > 15 μg/dL before the 1976 phase out. In contrast BLLs in low- and middle-income countries (LMICs )have remained elevated, with national mean BLLs above 5 μg/dL in multiple locations. Despite this, little is known about the continued nature and extent of lead exposure in LMICs. This thesis sought to characterize sources of human lead exposure in LMICs, quantify their impact, and propose methods of mitigation. It is comprised of 12 studies arranged in three chapters along these themes. In the first chapter, sources of human lead exposure in LMICs were evaluated through a systematic literature review and in situ assessment. In the second chapter, the attributable disease burden of some of those sources was quantified using common public health metrics, primarily Disability Adjusted Life Years (DALYs). Finally, in the third chapter, mitigation case studies were executed in three different countries and evaluated for their efficacy. The thesis contends that lead exposure in LMICs is primarily industrial in nature and results in a larger disease burden than is currently estimated. In addition it argues that cost effective measures exist to mitigate some of the more significant sources of exposure.