Lead intoxicated children in Kabwe, Zambia
Introduction
Kabwe is the fourth biggest town and capital of the central province of Zambia. The town has a long history of mining, which operated for more than 90 years and produced large quantities of lead (Pb) and zinc (Zn) until closure in 1994.
Lead is a toxic substance and chronic exposure causes serious adverse health effects. The pathways of exposure are mainly ingestion of Pb contaminated soil and dust, but inhalation as a route of entry can also be significant. Pb can cause acute and chronic intoxication. High exposure can cause severe colic-like abdominal pains, neurological symptoms, seizures, encephalopathy and finally death (World Health Organization, 2010).
Infants are at higher risk due to specific risk behaviors such as playing on bare soil, relevant hand to mouth activity and thus their oral uptake is greater compared with adults (World Health Organization, 2010). While high blood Pb levels (BLLs) have been associated with extensive adverse effects, evidence of low BLLs causing serious negative health effects is extensive and conclusive. The negative effect of Pb exposure during pregnancy to the fetus and during early childhood on the regular development of the brain has enormous adverse implications (Advisory Committee on Childhood Lead Poisoning Prevention, 2016, Needleman et al., 1990).
The CDC Reference Level for Pb is 5 µg Pb/dL blood (https://www.cdc.gov/nceh/lead/acclpp/blood_lead_levels.htm). Between 5 and 44 µg Pb/dL, actions to lower the body burden are recommended In the former “Kabwe lead poisoning management protocol” a Pb level of 20 µg Pb/dL was considered as minimum level for individual follow up (Project Technical Committee - Zambia Consolidated Copper Mines Investments Holdings, 2006). The medical intervention level for children is 45 µg Pb/dL. Children with confirmed Pb encephalopathy need to be hospitalized and treated individually (Advisory Committee on Childhood Lead Poisoning Prevention, 2016, Thurtle et al., 2014). Data from a large treatment survey in Nigeria indicates that oral chelation treatment with Chemet® (succimer, DMSA) is both safe and effective (Thurtle et al., 2014). However, chelation therapy without environmental intervention may prove futile since re-exposure will likely occur.
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Environmental assessments
Lead contaminated soils in Kabwe pose a serious environmental hazard. In 2003–2006, the “Copperbelt Environment Project” analyzed over 1000 soil samples for Pb in various townships. The results showed, that the soil “over a substantial area is highly contaminated with the metal”. “Median Pb concentrations of soil in townships in the vicinity of the mine inducing Kasanda (3008 mg/kg), Makandanyama (1613 mg/kg), Chowa (1233 mg/kg), Mutwe Wansofu (1148 mg/kg), Makululu (870 mg/kg) and Luangwa (507
Health assessments
Presently, there are three information sources on childhood BLLs in Kabwe; (1) data from the Copperbelt Environment Project; (2) data from projects of Pure Earth and (3) data from a University of Zambia with collaborators from Hokkaido University, Japan. A summary of BLL data is provided below.
Discussion
The existing data clearly establishes the severity of Pb exposure in Kabwe. Environmental data also support the observation that in certain housing areas of Kabwe, the recommended tolerable soil Pb level of 400 mg/kg is clearly exceeded (see Fig. 1 and Fig. 2). The soil levels measured by Pure Earth 2014 are in general higher compared to those reported by KSDS in 2006. We suspect this results from enhanced granularity now available with a portable XRF (rather than an actual increase in
Acknowledgement
Funding by Pure Earth is gratefully acknowledged (JC). Funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 603946 (Health and Environment-wide Associations based on Large population Surveys, HEALS) is acknowledged (SB).
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Social cost of mining-related lead (Pb) pollution in Kabwe, Zambia, and potential remediation measures
2023, Science of the Total EnvironmentA review on Pb-bearing nanoparticles, particulate matter and colloids released from mining and smelting activities
2022, Gondwana ResearchCitation Excerpt :The deposited PM and its alteration phases can cause adverse health effects to humans especially in highly contaminated areas or areas of low vegetation density such as in dry and semidry areas) (Pelfrene et al., 2011, Ettler et al., 2012c, 2019, Entwistle et al., 2019, Yabe et al., 2015, 2018, 2020). A soil highly contaminated with Pb has commonly Pb concentrations in the thousands to ten thousand mgkg−1 range such as in Trail, BC, Canada with a maximum of 17,000 mgKg−1 Pb (Schindler and Hochella, 2017) and Kabwe, Zambia with a maximum of 62,000 mgKg−1 Pb (Bose-O’Reilly et al., 2018). As the chemical and mineralogical composition as well as shape, and surface area (size) of altered and unaltered Pb-bearing PM derived from smelter and mining operations commonly differ, bioaccessibility of Pb from these different types of PM differs as well (see below; Ettler et al., 2012b, 2019; Boisa et al., 2014).