Limits...
Linking geological and health sciences to assess childhood lead poisoning from artisanal gold mining in Nigeria.

Plumlee GS, Durant JT, Morman SA, Neri A, Wolf RE, Dooyema CA, Hageman PL, Lowers HA, Fernette GL, Meeker GP, Benzel WM, Driscoll RL, Berry CJ, Crock JG, Goldstein HL, Adams M, Bartrem CL, Tirima S, Behbod B, von Lindern I, Brown MJ - Environ. Health Perspect. (2013)

Bottom Line: 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.Consumption of water and foodstuffs contaminated by the processing is likely lesser, but these are still significant exposure pathways.Mercury, arsenic, manganese, antimony, and crystalline silica exposures pose additional health threats.

View Article: PubMed Central - PubMed

Affiliation: US Geological Survey, Denver, Colorado 80225, USA. gplumlee@usgs.gov

ABSTRACT

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.

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Related in: MedlinePlus

Calculated daily lead uptake assuming exposures to processed ores, soils, and sweep samples from Zamfara. For each sample, measured gastric bioaccessibility of lead (from Figure 3) was translated into gastric bioavailability using equations in Drexler and Brattin (2007) [see Supplemental Material, Lead Uptake Calculations (http://dx.doi.org/10.1289/ehp.1206051)]. The gastric bioavailability was then translated into daily uptake amount using soil consumption rates for young children from the literature (U.S. EPA 2011b). Brown bars assume 10-mg/day soil consumption (unrealistically clean conditions), and yellow bars assume 500-mg/day soil consumption (very dusty but plausible conditions). Bar pairs show results for the corresponding samples in Figure 3, except that bar pairs labeled as sample duplicates are averages of sample duplicate analyses. Horizontal red lines show WHO (2011) dietary exposure levels for 12-kg child (3.6 µg/day) and 16-kg child (4.8 µg/day) known to adversely affect health, and FDA PTTILs (FDA 1993) for pregnant or lactating women (25 µg/day) and adults (75 µg/day). Although called “intake levels,” PTTILs are in effect uptake levels because they were derived assuming 48% absorption.
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f4: Calculated daily lead uptake assuming exposures to processed ores, soils, and sweep samples from Zamfara. For each sample, measured gastric bioaccessibility of lead (from Figure 3) was translated into gastric bioavailability using equations in Drexler and Brattin (2007) [see Supplemental Material, Lead Uptake Calculations (http://dx.doi.org/10.1289/ehp.1206051)]. The gastric bioavailability was then translated into daily uptake amount using soil consumption rates for young children from the literature (U.S. EPA 2011b). Brown bars assume 10-mg/day soil consumption (unrealistically clean conditions), and yellow bars assume 500-mg/day soil consumption (very dusty but plausible conditions). Bar pairs show results for the corresponding samples in Figure 3, except that bar pairs labeled as sample duplicates are averages of sample duplicate analyses. Horizontal red lines show WHO (2011) dietary exposure levels for 12-kg child (3.6 µg/day) and 16-kg child (4.8 µg/day) known to adversely affect health, and FDA PTTILs (FDA 1993) for pregnant or lactating women (25 µg/day) and adults (75 µg/day). Although called “intake levels,” PTTILs are in effect uptake levels because they were derived assuming 48% absorption.

Mentions: Figure 4 shows results of calculations estimating plausible ranges in daily lead uptake from inadvertent ingestion of the different processed ore, soil, and sweep samples we analyzed.


Linking geological and health sciences to assess childhood lead poisoning from artisanal gold mining in Nigeria.

Plumlee GS, Durant JT, Morman SA, Neri A, Wolf RE, Dooyema CA, Hageman PL, Lowers HA, Fernette GL, Meeker GP, Benzel WM, Driscoll RL, Berry CJ, Crock JG, Goldstein HL, Adams M, Bartrem CL, Tirima S, Behbod B, von Lindern I, Brown MJ - Environ. Health Perspect. (2013)

Calculated daily lead uptake assuming exposures to processed ores, soils, and sweep samples from Zamfara. For each sample, measured gastric bioaccessibility of lead (from Figure 3) was translated into gastric bioavailability using equations in Drexler and Brattin (2007) [see Supplemental Material, Lead Uptake Calculations (http://dx.doi.org/10.1289/ehp.1206051)]. The gastric bioavailability was then translated into daily uptake amount using soil consumption rates for young children from the literature (U.S. EPA 2011b). Brown bars assume 10-mg/day soil consumption (unrealistically clean conditions), and yellow bars assume 500-mg/day soil consumption (very dusty but plausible conditions). Bar pairs show results for the corresponding samples in Figure 3, except that bar pairs labeled as sample duplicates are averages of sample duplicate analyses. Horizontal red lines show WHO (2011) dietary exposure levels for 12-kg child (3.6 µg/day) and 16-kg child (4.8 µg/day) known to adversely affect health, and FDA PTTILs (FDA 1993) for pregnant or lactating women (25 µg/day) and adults (75 µg/day). Although called “intake levels,” PTTILs are in effect uptake levels because they were derived assuming 48% absorption.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672918&req=5

f4: Calculated daily lead uptake assuming exposures to processed ores, soils, and sweep samples from Zamfara. For each sample, measured gastric bioaccessibility of lead (from Figure 3) was translated into gastric bioavailability using equations in Drexler and Brattin (2007) [see Supplemental Material, Lead Uptake Calculations (http://dx.doi.org/10.1289/ehp.1206051)]. The gastric bioavailability was then translated into daily uptake amount using soil consumption rates for young children from the literature (U.S. EPA 2011b). Brown bars assume 10-mg/day soil consumption (unrealistically clean conditions), and yellow bars assume 500-mg/day soil consumption (very dusty but plausible conditions). Bar pairs show results for the corresponding samples in Figure 3, except that bar pairs labeled as sample duplicates are averages of sample duplicate analyses. Horizontal red lines show WHO (2011) dietary exposure levels for 12-kg child (3.6 µg/day) and 16-kg child (4.8 µg/day) known to adversely affect health, and FDA PTTILs (FDA 1993) for pregnant or lactating women (25 µg/day) and adults (75 µg/day). Although called “intake levels,” PTTILs are in effect uptake levels because they were derived assuming 48% absorption.
Mentions: Figure 4 shows results of calculations estimating plausible ranges in daily lead uptake from inadvertent ingestion of the different processed ore, soil, and sweep samples we analyzed.

Bottom Line: 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.Consumption of water and foodstuffs contaminated by the processing is likely lesser, but these are still significant exposure pathways.Mercury, arsenic, manganese, antimony, and crystalline silica exposures pose additional health threats.

View Article: PubMed Central - PubMed

Affiliation: US Geological Survey, Denver, Colorado 80225, USA. gplumlee@usgs.gov

ABSTRACT

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.

Show MeSH
Related in: MedlinePlus