1. Herman Gibb, PhD, MPH Gibb Epidemiology Consulting Arlington, VA, USA
Mercury exposure and health impacts among individuals in the artisanal & small-scale gold mining (ASGM) community
Herman Gibb, PhD, MPH
Gibb Epidemiology Consulting
Arlington, VA, USA
Use slide from the ICMGP 2013 (Edinburgh meeting) but change the affiliation from Tetra Tech Sciences to Gibb Epidemiology Consulting LLC, Arlington, VA

2. Different forms of mercury
Elemental mercury
Inorganic mercury (e.g., mercuric nitrate, mercuric chloride, mercurous chloride, mercuric sulfide, mercuric acetate)
Organic mercury (e.g., methylmercury, ethylmercury)
Herman - Do you want to combine slides 2 and 3 since there isn’t much on each?

3. Biomarkers of mercury Hair (methylmercury)
Blood (all forms of mercury)
Urine (elemental and inorganic mercury)

4. Mad as a hatter
In the 19th and 20th Centuries, inorganic mercury (mercuric nitrate) was used in the production of felt for hats. The hatters were exposed to mercury vapor from a reaction that released volatile free mercury.
As early as 1829, adverse health symptoms including mental confusion, emotional disturbances, and muscular weakness were reported among hatters.
A U.S. Public Health Service estimated that in 1934, 80% of American hat makers had mercurial tremors – what the workers referred to as “the shakes.”
The term “mad as a hatter” is associated with the syndrome.

5. The minamata incident
One of the most severe incidents of mercury poisoning occurred in Minamata, Japan, when a local company dumped what is estimated to have been 27 tons of methylmercury into Minamata Bay over a period of
The methylmercury accumulated in shellfish and fish.
Consumption of the fish and shellfish resulted in the deaths of cats, dogs, pigs, and humans. What became known as Minamata disease is a neurologic syndrome caused by severe mercury poisoning.
Children born to mothers who consumed the fish and shellfish were born with severe congenital deformities.
Minamata Disease Symptoms:
Ataxia
Numbness in the hands and feet
General muscle weakness
Narrowing in the field of vision
Damage to hearing and speech
Extreme cases:
Insanity
Paralysis
Coma
Death

6. The minamata convention
The Convention is an international treaty designed to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds.
The treaty was developed under the aegis of the United Nations Environment Programme.
The Convention was opened for signature in October 2013 in Minamata, Japan.
There are now 102 signatories (countries) to the Convention.
Herman - I broke this into two slides because it was too much for one slide

7. The minamata convention
Article 7 and Annex C of the Convention address artisanal and small-scale gold mining (ASGM) and the development of national plans for ASGM. The Convention calls for nations to gather health data, train health care workers, and raise awareness in regard to ASGM activity.
All countries in South America are signatories of the Convention with the exception of Suriname.

8. How and why is mercury used in asgm?
Mercury forms an amalgam with the ore.
Mercury is heated and vaporizes leaving the gold behind.
The method is cheaper than other methods, can be done by one person and is quick and easy.
UNEP 2012
UNEP 2012

9. How big is the problem?
Mercury from ASGM is responsible for 37% of the global emissions of mercury and is the largest single source of air and water mercury.
Mercury vapors in the air around amalgam burning sites can be alarmingly high and almost always exceeds the WHO limit for public exposure of 1.0 µg/m³.
UNEP 2013

10. How widespread is the problem?
Approximately 15 million people, including approximately 3 million women and children, participate in the ASGM industry in 70 countries.
These 70 countries are found primarily in East and Southeast Asia, Sub-Saharan Africa & South America.
The countries with the most mercury emissions from ASGM are the following: Columbia, Ecuador, Peru, China, Philippines, Indonesia, Burkina Faso, and Ghana
Countries with n=500,000, ASGM miners are: Brazil, Tanzania, Indonesia, Philippines
Countries with n=100,000 miners include Bolivia, Peru, Democratic Republic of Congo, Burkina Faso and Mongolia
UNEP 2013

11. Health effects among those engaged in ASgm
Study
Where conducted?
Effect(s) observed
Yard et al. (2012)
Peru
Neurologic, kidney dysfunction, digestive system disorder
Harari et al. (2012)
Ecuador
Tremor
Tomicic et al. (2011)
Burkina Faso
Neurologic
Bose-O’Reilly et al. (2010)
Indonesia
Mercury intoxication (based on a merger of medical score and biomonitoring results)
Gardner et al. (2011)
Brazil
Higher prevalence of anti-nuclear autoantibodies (ANA) and anti-nucleolar autoantibodies (ANoA) compared to control (i.e., immunological effect)
Bose-O’Reilly et al. (2008)
Zimbabwe
Mercury intoxication (based on a merger of medical score and biomonitoring results) found in children
Silva et al. (2004)
High prevalence of detectable ANA and ANoA compared to controls
Drake et al. (2001)
Venezuela
Increase in NAG (protein in urine considered evidence of preclinical, nonspecific damage to proximal tubule of kidney)
Source: Gibb & O’Leary 2014

12. Health effects AMONG those indirectly exposed TO ASgm
Individuals not directly engaged in ASGM but living in ASGM communities or communities near ASGM
Study
Where conducted?
Effect(s) observed
Nyland et al. (2011)
Brazil
Immunologic effect (higher prevalence of ANA and ANoA compared to controls)
Tian et al. (2010)
China
Urinary mercury associated with urinary β2-microglobulin and N-acetyl-β-D-glucosaminidase (NAG) (biomarkers of preclinical kidney effects)
Alves et al. (2006)
Immunologic effect (higher prevalence of ANA among riverine fish eaters compared to controls)
Cordier et al. (2002)
French Guiana
Neurologic effects seen in mothers, no major effects observed in children
Harada et al. (2001)
Sensory disturbance; several subjects were diagnosed with Minimata disease
Akagi et al. (2000)
Philippines
Gingival discoloration, adenopathy, underweight, and dermatologic abnormalities found in children
Grandjean et al. (1999)
Neurologic effects
Lebel et al. (1998)
Source: Gibb & O’Leary 2014

13. Urinary mercury concentrations AMONG those working or living in asgm communities
Herman – I was not able to high light so I used these arrows to indicate the South American studies
neurologic signs
kidney effects

14. Mean urinary mercury levels of various exposure groups
Hurtado et al. 2006
Mean urinary mercury levels of various exposure groups
50 µg/L has been associated with kidney damage
100 µg/L is associated with neurologic effects

15. Mean & range of hair mercury concentrations of female residents of ASGM communities
2.5 µg/g hair mercury = WHO’s Provisional Tolerable Weekly Intake (PTWI)
PTWI

16. Mean & range of hair mercury Concentrations of children and infants of asgm communities
Herman – using arrows here would have crowded the slide so I changed the numbers to orange for the South American studies

17. Air measurements at ASGM Operations in Venezuela & Peru
Drake et al (Venezuela)
Range: 0.1-6,315 µg/m³
Mean: 183 µg/m³
20% of the measurements (N=61) were above 50 µg/m³
Hurtado et al (Peru)
Amalgam smelter
Range: 530-4,440 µg/m³
Mean: 2,423.3 µg/m³
N=6
Working and/or living in quimbaletes
Range: µg/m³
Mean: 30.5 µg/m³
Living in artisanal mining town
Range: 3-23 µg/m³
Mean: 11.8 µg/m³
N=5
Concentration at which health effect is reported to occur
Health effect
WHO (2000)
15 µg/m3
Renal tubular effects & changes in plasma enzymes
30 µg/m3
Tremor
Drake et al. (2001): 8 hour TWA airborne mercury exposure at gold mining operations in Venezuela
The highest exposure, 6,315 µg/m3, is approximately 210 times the exposure level at which tremors are observed and approximately 420 times the exposure level at which renal tubular effects are estimated to occur.
The mean airborne mercury exposure, 183 µg/m3, is approximately 6 times the exposure level at which tremors are observed and approximately 12 times the exposure level at which renal tubular effects are estimated to occur

18. ASGM Mercury consumption and associated emissions In south america
[Adapted from UNEP (2013) Technical Background Report for the Global Mercury Assessment]
Country
Quality of Data*
ASGM Mercury Use (tons)
% of total Hg applied to concentrate amalgamation
% of total Hg applied to whole ore amalgamation
Emission
Factor
Year of most recent data
Mean air emission (tons)
Min
Mean
Max
Bolivia 4
84.0
120.0
156.0 25 75
0.38
2012
45.000
Brazil
31.5
45.0
58.5 50
0.50
2007
22.500
Chile 2
1.0
4.0
7.0
2009
2.000
Colombia 3
90.0
180.0
270.0 17 83
0.33
60.000
Ecuador
25.0
50.0
75.0 20 80
0.35
17.500
French Guiana
3.8
7.5
11.3
100
0.75
2008
5.625
Paraguay 1
0.1
0.3
0.5
0.225
Peru
49.0
70.0
91.0
2010
26.25
Venezuela
15.0
22.5
2005
Herman – I think this info doesn’t need to be on the slide itself (so I added the note instead and you can always explain the following, if needed)
Class 1 = presence/absence, no quantitative information, error can be greater than ±100%;
Class 2 = some indication of quantity of Hg used, estimated average error ±75%;
Class 3 = quantitative data but not significantly updated within past five years, error ±50%;
Class 4 = recent quantitative data; error ±30%;
Emission factor for concentrate amalgamation = 0.75 (1/1.3); Emission factor for whole ore amalgamation = 0.25 (1/4).
*Quality of Data: Worst (1) to Best (4)

19. Summary
The problem of mercury emissions from ASGM is widespread – ASGM occurs in 70 countries and is responsible for 37% of the global emissions of mercury
Health effects associated with ASGM have been reported in at least 10 countries on 3 continents. These effects are primarily neurologic, kidney, and immunologic.
Urinary mercury concentrations in ASGM communities are significantly elevated above concentrations associated with health effects.
Hair mercury concentrations in women living in or near ASGM communities are significantly elevated above the hair mercury concentrations associated with WHO’s Provisional Tolerable Weekly Intake.
Hair mercury concentrations in children living in or near ASGM communities are elevated above those of other fish eating populations.
Brazil has the most gold miners in South America (estimated 500,000), but the amount of mercury emissions (tons released) is estimated to be higher in Bolivia, Colombia, and Peru.