**5. Why and how lead poisoning occurs in Zamfara state**

Zamfara State, Nigeria has since at least early 2010 begun to witness serious cases of heavy metals poisoning, which translated into a huge number of deaths in human populations particularly children aged 0 to 5 years. There is also the fear that tones of heavy metals (mostly lead) released due to unsafe gold mining practices in many parts of the State (Zamfara) may have the tendency to accumulate and concentrate along the food chain as they (heavy metals) move from one trophic level to the next. This would in turn affect not only the physical or abiotic component of the environment (comprising of soil, water and air) but also the biological or biotic component (comprising of humans, other animals and plants). Consequently, the consumption of crops grown on lead-contaminated fields and animals fed on pasture from these mining areas will constitute a potential risk for ailments associated with heavy metals poisoning. In addition, the chronic effects of poisoning from the metal pollutants on the apparently healthy surviving populations can translate into serious clinical problems that are never imagined [2, 10, 12–14].

Lead is a naturally occurring metal in soil [15]. It was however unusual to find such high levels of lead in these communities [5]. Apart from the seven villages in Zamfara State that have undergone environmental remediation from June 2010 to March 2011, at least 43 additional villages in the State were reported to have confirmed cases of lead poisoning with the affected children having blood lead concentration greater than 45 μg/dL and therefore require chelating therapy [2]. In Bagega town (Anka LGA), the level of pollution was very alarming. Many family compounds and community areas in the town had soil lead concentrations above 1000 ppm (in the USA, 400 ppm is the blood lead concentration limit, where there are children), and an estimated number of 1500 children were reported to have been poisoned with lead in Bagega alone [7].

Mining had become an important source of income for the villagers in the area. It had become almost impossible for the villagers to stop mining completely [6]. Having realized a lead poisoning outbreak of huge magnitude among children in Zamfara State, the Nigerian authorities requested the World Health Organization (WHO) to provide further technical and financial assistance to resolve the problem and prevent future reoccurrences. A team of experts comprising three epidemiologists, a chemical toxicologist, a pediatrician, an environmental health expert and a laboratory specialist arrived in Zamfara State in June 2010 to investigate the lead poisoning situation [7]. While the

## *Lead Poisoning in Zamfara State Nigeria: Effects on Environmental Health DOI: http://dx.doi.org/10.5772/intechopen.112909*

response team was busy investigating the lead poisoning outbreak, Blacksmith Institute (BI) sent a team from TerraGraphics Engineering Incorporated (TG) to conduct an environmental assessment (physical) of the situation. The two teams worked together with officials of the Federal Government of Nigeria and Zamfara State authorities, WHO country office in Nigeria and MSF. In their report dated 7th July, 2010, members of both teams have confirmed a high degree of environmental lead contamination from gold mining activities in five additional villages in the state namely Tungar–daji, Abare, Duza, Sunke (Anka LGA) and Tungar–guru (Bukkuyum LGA) [8].

High lead concentrations from unsafe artisanal gold mining and processing practices continued to cause lead poisoning mortality in younger children and morbidity in older populations [8]. The primary pathway of exposure for young children is through soil ingestion. Consequently, even if the exposure to lead had to stop now, the children already having lead poisoning would require years of expensive medical treatment [9]. Investigation reports on groundwater pollution in the area have shown that lead pollution remained confined to areas (wells and ponds) where mining and processing of gold from lead ore had taken place and had not spread through the ground water aquifer [2]. In some drinking wells, concentrations of lead 10 to 15 times greater than the WHO recommended limit of 10 μg/L have been found. Also, reports on surface water sources (ponds, rivers and lakes) in the mining areas showed higher concentrations of lead up to more than 10,000 μg/dl, which is 10 times greater than the exposure limit recommended by the Food and Agricultural Organization (FAO) of the United Nations (UN) for livestock [10].

Investigations on soil generally showed concentrations up to 8 percent higher in locations closer to drinking water wells and other surface water sources. This was suspected to have been caused by lead dust deposition and soil run-off from sites where lead-contaminated ore was being processed. Gold processing was done by repeated washing of the lead ore using metal head pans by decantation process to extract gold. The contaminated water and soil containing the lead ore were continuously spread all over surfaces within the residential compounds and surrounding areas [5]. At ore processing locations, incidental inhalation and ingestion of soil are a common source of exposure particularly for infants and toddlers, ingestion commonly occurs via hand-to-mouth behavior and eating food with contaminated hands [2]. Reports indicated that lead poisoning incidence from illegal mining activities in Zamfara State from 2010 to 2011 had led to the death of at least 735 children, mostly aged 0 to 5 years, and has left thousands of others ill with the lead poisoning [11, 16].
