Monday 26 September 2022

Osun River Contamination: Can we learn from the 2011 Zamfara state lead poisoning?

On the eve of the celebration of Osun river deity by Osun Osogbo worshippers, the state government warned against the consumption of Osun water.

The state government through its commissioner for Health, Dr Rafiu Isamotu, says the water is not good for drinking because it contains lead and other dangerous elements hazardous to human health.

But with test conducted by a non-profit organisation, Urban Alert recently revealed the river to be heavily contaminated with lead, mercury, cyanide and other elements.

The contamination it was gathered, emanated from the intensive activities of artisanal miners along the river basin spanning scores of kilometres, especially along Ijesaland axis of the state.

According to an Iponda-Ijesa resident, Ademola Adeboyejo, what the miners do on a daily basis is to rinse the mud/clay/granite brought from the mining site with the water to extract gold and other mineral deposit, turning water that is naturally colourless to whitish.

 2011, in Zamfara state, Nigeria, investigations led by the US Centers for Disease Control and Prevention (CDC), in collaboration with Federal and Zamfara State authorities, MSF, Blacksmith Institute and the World Health Organization (WHO), revealed that an outbreak was caused by acute lead poisoning associated with artisanal gold ore processing. 

More than 400 children under the age of five died, and hundreds more were confirmed to be at risk of death or serious acute and long-term irreversible health effects due to extremely high levels of lead. Of the children tested in two villages, 100% exceeded 10 !g/dL (the international standard maximum for lead in blood), with some levels measuring as high as 700 !g/dL.

The source was massive environmental contamination from the informal processing of lead-rich ore to extract gold. Men brought rock ore to the villages, where the women ground it into fine particles. This process resulted in the extensive dispersal of lead-containing dust throughout the villages, including within family compounds.

Seven villages were initially identified for immediate remediation. Seven more villages were later identified for clean up, including Bagega, which alone was double the size of the first seven. In all villages, including in family homes and compounds, soil lead concentrations exceeded 100,000 ppm, far above the internationally accepted standard of 400 ppm for residential areas. Primary exposure routes for children and adults were:

1) Incidental ingestion of soil and dust

2) Consumption of food contaminated by soil and dust sources

3) Ingestion of contaminated water

4) Inhalation of contaminated dust. Consequently, an estimated 2500 children accumulated life-threatening levels of lead in their blood, with thousands more at risk of permanent brain damage.

Never before has there been a lead poisoning epidemic of this magnitude anywhere in the world. People were dying every day. On-going exposure and blood lead absorption were higher than any previously recorded in the international literature. There was a universal lack of international experience and cleanup models to address such an emergency. In a word, the situation was “unprecedented.”


In June 2010, Zamfara State and Nigerian Federal health authorities formally requested assistance from WHO, CDC, MSF and the Blacksmith Institute to address this problem. MSF offered chelation therapy, a treatment that removes lead from the body, to children with critical levels of lead. However, in order to prevent recontamination, it was required that treated children not return to a contaminated environment. Environmental assessments indicated that lead exposure could be eliminated by the removal and replacement of topsoil and by thorough cleaning/removal of dust from all interior spaces, homes and compounds.

From June 2010 to March 2011, Blacksmith Institute conducted environmental decontamination in seven villages in collaboration with Terragraphics and local authorities. Local villagers were trained to assist with the clean-up operations, including cleaning of homes. Contaminated soil was removed to secure landfills and replaced with clean soil. In total, seven villages were remediated, including 282 residential compounds, 107 exterior areas and 23 processing ponds, allowing for MSF to provide chelation treatment for more than 1000 children. The project also removed highly contaminated material from 7 ponds that were used to make bricks for compound repairs. In addition, UNICEF and project partners mobilized the communities and established male and female advocacy programs to raise awareness, facilitate remediation and support prevention of recontamination.
Furthermore, the project trained more than 200 Ministry, village and private personnel, building local capacity to conduct remediation activities, and provided guidance and assistance to the State in how to address mineral processing activities.

A total of 282 residential compounds, 107 exterior areas, and 23 processing ponds have been remediated in five villages. In Bagega, a large landfill has been constructed and prepared for contaminated soils and industrial waste; residential areas, village exteriors, brick-making ponds, and the Bagega industrial site have been assessed; and preliminary design and cost estimates prepared.

Highly contaminated materials from seven ponds in Yarlgama and Dareta–used to make bricks for compound repairs after a particularly damaging rainy season–have been removed.

Male and female advocacy programs have been established to facilitate remediation and support prevention of recontamination, among other community response activities. Villagers are increasingly aware of the dangers of artisanal mining and measures required to protect their families.

The capacity of Zamfara state and local level government to undertake future cleanup has been developed with over 200 ministry, local village, and private personnel trained in appropriate technology. And the international partnership has provided assistance. 

(Publication materials from Leadership NewspaBorders Médecins Sans Frontières MSF/Doctors Without Borders journal)

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