Maternal blood lead levels and proximity to legacy mining contamination in Kabwe, Zambia: socioeconomic disparities and potential implications on fetal health

Abstract

Legacy lead (Pb) contamination from a century-long Pb-Zn mining operation (1906-1994) continues to pose severe environmental health threats in Kabwe, Zambia, one of the world's most polluted sites. While elevated blood lead levels (BLLs) in children are well-documented, maternal exposure remains understudied despite its critical implications for fetal development. We conducted a cross-sectional biomonitoring study among 510 pregnant women across four townships in Kabwe (Makululu, Kasanda, Katondo, and Mahatma Gandhi), stratified by proximity to the former mine (1.5-4.5 km). Sociodemographic and clinical data were collected utilizing a structured questionnaire. Venous blood samples were analyzed for Pb using graphite furnace atomic absorption spectrophotometry (GFAAS), with rigorous quality control (recovery: 92.3-95.1%; MDL: 0.012 µg/dL). Maternal BLLs varied significantly by township (p < 0.001): median BLLs were highest in Makululu (6.5 µg/dL; 84.4% elevated), followed by Kasanda (3.4 µg/dL; 48.1%), and lowest in Katondo (1.8 µg/dL; 10.0%) and Mahatma Gandhi (1.6 µg/dL; 8.8%). Overall, 43.7% of women exceeded the reference level of 3.5 µg/dL, disproportionately affecting those in the informal settlements near the mine waste. Elevated BLLs were significantly associated with longer years of stay in the area (p = 0.007), unemployment (p < 0.001), smoking (p = 0.021), lower BMI (p = 0.023), and higher gravidity (p < 0.001), reflecting intersecting environmental, biological and socioeconomic vulnerabilities. Maternal Pb exposure in Kabwe remains alarmingly high, especially in mining-proximal, low-resource communities, underscoring a critical environmental injustice. Given potential for Pb to cross the placenta and documented links to negative birth outcomes, urgent interventions, including regular maternal screening and policy reform, are needed to potentially protect the health of the unborn baby and break cycles of intergenerational toxicity.