Linking Geological and Health Sciences to Assess Childhood Lead Poisoning from Artisanal Gold Mining in Nigeria

Background: In 2010, Médecins Sans Frontières discovered a lead poisoning outbreak linked to artisanal gold processing in northwestern Nigeria. The outbreak has killed approximately 400 young children and affected thousands more. Objectives: Our aim was to undertake an interdisciplinary geological- and health-science assessment to clarify lead sources and exposure pathways, identify additional toxicants of concern and populations at risk, and examine potential for similar lead poisoning globally. Methods: We applied diverse analytical methods to ore samples, soil and sweep samples from villages and family compounds, and plant foodstuff samples. Results: Natural weathering of lead-rich gold ores before mining formed abundant, highly gastric-bioaccessible lead carbonates. The same fingerprint of lead minerals found in all sample types confirms that ore processing caused extreme contamination, with up to 185,000 ppm lead in soils/sweep samples and up to 145 ppm lead in plant foodstuffs. Incidental ingestion of soils via hand-to-mouth transmission and of dusts cleared from the respiratory tract is the dominant exposure pathway. Consumption of water and foodstuffs contaminated by the processing is likely lesser, but these are still significant exposure pathways. Although young children suffered the most immediate and severe consequences, results indicate that older children, adult workers, pregnant women, and breastfed infants are also at risk for lead poisoning. Mercury, arsenic, manganese, antimony, and crystalline silica exposures pose additional health threats. Conclusions: Results inform ongoing efforts in Nigeria to assess lead contamination and poisoning, treat victims, mitigate exposures, and remediate contamination. Ore deposit geology, pre-mining weathering, and burgeoning artisanal mining may combine to cause similar lead poisoning disasters elsewhere globally.

[1]  L. de Ravello,et al.  Childhood Lead Poisoning Associated with Gold Ore Processing: a Village-Level Investigation—Zamfara State, Nigeria, October–November 2010 , 2012, Environmental health perspectives.

[2]  Nasir Sani-Gwarzo,et al.  Outbreak of Fatal Childhood Lead Poisoning Related to Artisanal Gold Mining in Northwestern Nigeria, 2010 , 2011, Environmental health perspectives.

[3]  Suzette A. Morman,et al.  Mine Wastes and Human Health , 2011 .

[4]  Joel Schwartz,et al.  Associations of Early Childhood Manganese and Lead Coexposure with Neurodevelopment , 2011, Environmental health perspectives.

[5]  A. Bieganowski,et al.  Methodological aspects of determining soil particle-size distribution using the laser diffraction method. , 2011 .

[6]  Kathleen S. Smith,et al.  Measurement of total Zn and Zn isotope ratios by quadrupole ICP-MS for evaluation of Zn uptake in gills of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). , 2009, Talanta.

[7]  David B. Smith,et al.  Application of in vitro extraction studies to evaluate element bioaccessibility in soils from a transect across the United States and Canada. , 2009 .

[8]  Sergio Piomelli,et al.  Childhood lead poisoning , 2009 .

[9]  W. Brattin,et al.  An In Vitro Procedure for Estimation of Lead Relative Bioavailability: With Validation , 2007 .

[10]  S. Casteel,et al.  Estimation of Relative Bioavailability of Lead in Soil and Soil-Like Materials Using Young Swine , 2006, Environmental health perspectives.

[11]  J. Gaffney,et al.  Urban aerosols and their impacts : lessons learned from the World Trade Center Tragedy , 2005 .

[12]  S. Wilbur,et al.  Using the ATSDR Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures. , 2004, Environmental toxicology and pharmacology.

[13]  I. Garba.  Geochemical characteristics of mesothermal gold mineralisation in the Pan-African (600 ± 150 Ma) basement of Nigeria , 2003 .

[14]  Gavin Hilson,et al.  The Environmental Impact of Small-Scale Gold Mining in Ghana: Identifying Problems and Possible Solutions , 2002 .

[15]  N. Skovgaard.  Safety evaluation of certain food additives and contaminants , 2000 .

[16]  Gregg Alan Swayze,et al.  Materials characterization of dusts generated by the collapse of the World Trade Center , 2009 .

[17]  P. Hageman.  Determination of Mercury in Aqueous and Geologic Materials by Continuous Flow-Cold Vapor-Atomic Fluorescence Spectrometry (CVAFS) , 2007 .

[18]  P. Hageman.  U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials , 2007 .

[19]  METHOD 6200 - FIELD PORTABLE X-RAY FLUORESCENCE SPECTROMETRY FOR THE DETERMINATION OF ELEMENTAL CONCENTRATIONS IN SOIL AND SEDI , 2003 .

[20]  J. E. Taggart,et al.  Analytical methods for chemical analysis of geologic and other materials, U.S. Geological Survey , 2002 .

[21]  United Nations.  OFFICE FOR THE COORDINATION OF HUMANITARIAN AFFAIRS , 2000 .

[22]  P. Briggs,et al.  The determination of forty two elements in geological materials by inductively coupled plasma-mass spectrometry , 1999 .

[23]  Ron Jenkins,et al.  Introduction to X-ray powder diffractometry , 1996 .

[24]  Y ACRÓNIMOS,et al.  ATSDR (Agency for Toxic Substances and Disease Registry) case studies in environmental medicine. Vinyl chloride toxicity. , 1990, Journal of toxicology. Clinical toxicology.