Spatial Variation in Residential Soil Lead Contamination and Associated Exposure Risks for Pregnant Women in Kabwe, Zambia

Abstract

Kabwe, Zambia, has experienced persistent environmental lead (Pb) contamination following decades of lead-Zinc mining and smelting activities. Although spatial variation in Pb distribution has been documented, limited data exist on how these patterns translate into exposure risks for pregnant women, a highly vulnerable population. Studies have revealed that once absorbed, Pb accumulates in bones for decades where it becomes a source of endogenous exposure for pregnant women through bone resorption, resulting in potential irreversible health effects on the unborn baby. The present study was conducted to determine Pb levels in soils from homes of pregnant women living in selected townships of Kabwe District, Zambia. A comparative Cross Sectional study was conducted where sampling of study population involved three stages involving Health facilities, pregnant women and households for soil sampling. Health facilities were purposively sampled based on their provision of maternity services and location in proximity to and away from the Pb mine. Pregnant women were sampled using Simple Random Sampling based on antenatal attendance registers. Then households where the women resided were purposively selected for soil sampling. A total of 510 households were included in the study, with township-specific sample sizes proportionally allocated based on population served by the Health Facilities: Makululu (179), Kasanda (106), Katondo (100), and Mahatma Gandhi (125).. Lead levels were analysed using a Microwave Plasma Atomic Emission Spectrometer. Data were analysed in R version 4.5.1 and summarised using frequency tables, scatterplots, and bar charts. The median soil Pb concentration was 389.8 mg/kg (IQR: 53.4, 2,044.6), with 48.8% of households exceeding the maximum limit of 400 mg/kg. The highest concentrations were found in Makululu (2,044.6 mg/kg) and Kasanda (916.7 mg/kg) townships, while Katondo (44.3 mg/kg) and Mahatma Gandhi (47.9 mg/kg) townships recorded significantly lower levels (p<0.001). Residential proximity to the historical mining site remains a major determinant of soil Pb contamination and exposure risk among pregnant women in Kabwe. In order to reduce exposure, a coordinated, multisectoral action is required. The Kabwe Municipal Council should prioritize soil remediation and dust control in high-risk areas, while the Ministry of Infrastructure, Housing and Urban Development should improve housing units and paving of Makululu to reduce dust exposure. The Ministry of Health must integrate routine Pb screening and management into antenatal and child health services alongside lead prevention awareness and education programs for communities. The Zambia Environmental Management Agency should enforce environmental regulations to prevent further contamination.