Transcript Drake et al. 2001

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
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)
Biomarkers of
mercury
• Hair (methylmercury)
• Blood (all forms of mercury)
• Urine (elemental and inorganic mercury)
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.
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 1932-1968.
• 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
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.
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.
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
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
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.
UNEP 2013
Health effects among those
engaged in ASgm
Study
Where
conducted?
Yard et al. (2012)
Peru
Harari et al. (2012)
Ecuador
Tomicic et al. (2011)
Burkina Faso
Bose-O’Reilly et al. (2010)
Indonesia
Effect(s) observed
Neurologic, kidney dysfunction, digestive system disorder
Tremor
Neurologic
Mercury intoxication (based on a merger of medical score and
biomonitoring results)
Higher prevalence of anti-nuclear autoantibodies (ANA) and
anti-nucleolar autoantibodies (ANoA) compared to control
(i.e., immunological effect)
Gardner et al. (2011)
Brazil
Bose-O’Reilly et al. (2008)
Indonesia
Zimbabwe
Silva et al. (2004)
Brazil
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
Mercury intoxication (based on a merger of medical score and
biomonitoring results) found in children
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?
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 Nacetyl-β-D-glucosaminidase (NAG) (biomarkers of preclinical kidney
effects)
Alves et al. (2006)
Brazil
Immunologic effect (higher prevalence of ANA among riverine fish
eaters compared to controls)
Cordier et al. (2002)
French Guiana
Harada et al. (2001)
Brazil
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)
Brazil
Neurologic effects
Lebel et al. (1998)
Brazil
Neurologic effects
Source: Gibb & O’Leary 2014
Effect(s) observed
Neurologic effects seen in mothers, no major effects observed in
children
Urinary mercury concentrations
AMONG those working or living in
asgm communities
900
800
Urinary Mercury (µg/g-Cr)
700
600
500
400
300
200
100
neurologic signs
kidney effects
0
Study Author and Year
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
Mean & range of hair mercury
concentrations of female
residents of ASGM communities
100
95
90
85
80
75
Hair Mercury (µg/g)
70
65
60
55
50
45
40
35
30
25
20
14.08
15
11.4
10
5
1.12
8.11
9.39
8.25
1.6
0
Hacon et al.
2000
Barbosa et al.
1998
Barbosa et al. Malm et al. 2010 Pinheiro et al.
1998
2005
Study
Pinheiro et al.
2005
Cordier et al.
1998
PTWI
Mean & range of hair mercury
Concentrations of children and
infants of asgm communities
80
Hair Mercury (µg/g)
70
60
50
40
30
25.4
20
10
16.1
4.0
1.9
3.8
7.3
10.8
13.4 11.9
17.7
8.6
2.5
0
Study
6.0
1.0
0.9
3.4
AIR MEASUREMENTS AT ASGM
OPERATIONS IN VENEZUELA & PERU
Drake et al. 2001 (Venezuela)
Hurtado et al. 2006 (Peru)
• Range: 0.1-6,315 µg/m³
Amalgam smelter
• Mean: 183 µg/m³
• Range: 530-4,440 µg/m³
• 20% of the measurements (N=61) were above
50 µg/m³
• Mean: 2,423.3 µg/m³
Concentration at
which health effect
is reported to occur
WHO
(2000)
WHO
(2000)
15
µg/m3
• N=6
Working and/or living in quimbaletes
Health effect
• Range: 12-55 µg/m³
• Mean: 30.5 µg/m³
Renal tubular effects
& changes in plasma
enzymes
• N=6
Living in artisanal mining town
• Range: 3-23 µg/m³
30 µg/m3
Tremor
• Mean: 11.8 µg/m³
• N=5
ASGM Mercury consumption and
associated emissions In south america
[Adapted from UNEP (2013) Technical Background Report for the
Global Mercury Assessment]
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)
Quality
of
Data*
Min
Mean
Max
Bolivia
4
84.0
120.0
156.0
25
75
0.38
2012
45.000
Brazil
Chile
4
2
31.5
1.0
45.0
4.0
58.5
7.0
50
50
50
50
0.50
0.50
2007
2009
22.500
2.000
Colombia
3
90.0
180.0
270.0
17
83
0.33
2012
60.000
Ecuador
French
Guiana
Paraguay
Peru
3
25.0
50.0
75.0
20
80
0.35
2007
17.500
3
3.8
7.5
11.3
100
0
0.75
2008
5.625
1
4
0.1
49.0
0.3
70.0
0.5
91.0
100
25
0
75
0.75
0.38
2012
2010
0.225
26.25
Venezuela
3
7.5
15.0
22.5
25
75
0.38
2005
5.625
Country
*Quality of Data: Worst (1) to Best (4)
Summary
1.
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
2.
Health effects associated with ASGM have been reported in at least 10
countries on 3 continents. These effects are primarily neurologic, kidney, and
immunologic.
3.
Urinary mercury concentrations in ASGM communities are significantly
elevated above concentrations associated with health effects.
4.
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.
5.
Hair mercury concentrations in children living in or near ASGM
communities are elevated above those of other fish eating populations.
6.
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.