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4
Global MerIcur y Project
e
Project EG/GLO/01/G34
Removal of Barriers to Introduction of Cleaner Artisanal Gold Mining and
Extraction Technologies
Protocols for Environmental and Health Assessment of Mercury
Released by Artisanal and Small-Scale Gold Miners
Global Mercu Pro'ect Coordination Unit
Pablo Huidobro, Project Manager, UNIDO
Marcello M. Veiga, Chief Technical Advisor, UNIDO
Svitlana Bogoslavska, Administrative Assistant, VNIDO
Prima Authors
Marcello M. Veiga
University of British Columbia, Dept. Mining Engineering
63SO Stores Rd. , Vancouver, BC, V6T IZ4, Canada
Randy F. Baker
Azimuth Consulting Group
218-2902 W. Broadway Ave, , Vancouver, BC, V6K 2G8, Canada
E~ditin: Mavin B. I ried and Denise Withers
Covers: Joao Pedro Veiga using UNIDO photographs from Venezuela and
Lao PDR
Disclaimer: The designations employed and the presentation vf' the material
in this document do not imply the expression of any opinion whatsoever of
the Secretariat of the Unit'ed Nations Industrial Development Organization
(UN/DO) concerning the legal status of any country, territory, city or area of
its authorities, or concerning the delimitation ofits frontiers or boundaries.
Mention of company names and commercial products does not imply the
endorsement of UN1DO,
Protocols for Environmental and Health Assessment of Mercury
Released by Artisanal and Small-Scale Gold Miners
Global Mercury Project
UNIDO, Vienna International Center
P. O. Box 300
A-1400 Vienna, Austria
www. globalrnercury. org
Children and women are mai n victims of the misuse of mercury by
artisanal gold miners
Protocols for Environmental and Health Assessment of Mercury
Released by Artisanal and Small-Scale Gold Miners/M. M, Veiga,
R, F, Baker/Vienna, Austria: GFF/UNDP/UNIDO, 2004, 289p,
I, mercury pollution, 2. artisanal gold mining, 3. environmental
and health assesstnent, 4. tnonitoring methods.
ISBN 92-1-106429-5 UNIDO ID:ID/422
UN Sales No. ; E, 04. II. B.2 3
9 789211 064292
Gtobat Mercury Proj ect —P rotocols for Environmental any/ llealth Assessment
Summary
Artisanal and small-scale gold mining (ASM) is a poverty-driven activity that
provides an important source of livelihood for rural communities. As the
price of gold has been increasing, the number of artisanal gold miners has
risen to between 10 and 15 million people worldwide, producing from 500 to
800 tonnes of gold/a and emitting as much as 800-1000 tonnes/a of mercury
(Hg). These activities are frequently accompanied by extensive
environmental degradation and deplorable socio-economic conditions, both
during operations and long after mining activities have ceased,
One option fo determine the extent of environmental and human health
effects of ASM Hg is to conduct an Environmental Assessment (EA). In
general, EA is a tool used to identify, predict adverse effects and determine if
mitigative actions are required.
However, the methodologies used in EA for large mining projects involving
heavy metals are not ideally suited to assess the effects caused by Hg released
by ASM in developing countries. This means that environmental assessments
of ASM activities must be innovative and adapted to particular situations in
the different countries where the activities take place. This is especially true
when working with artisanal miners in impoverished and developing
countries, where remote and difficult environments with little infrastructure
and logistic support can pose many challenges.
Metallic mercury, which is the main form of Hg released by ASM, is
capricious and difficult to work with. Because of the naturally volatile state
of Hg and other confounding anthropogenic sources of Hg, this makes data
interpretation difficult. Perhaps more importantly, the transformation of
metallic I-lg into its most toxic form, methylmercury (MeHg), is not clearly
understood and there are no general rules governing this transformation,
When Environmental and Health Assessments (E&HA) are conducted to
determine Hg exposure, geochemical and biological samples should be
carefully chosen to fulfill assessment objectives. In most cases, limitations of
resources and time result in "short cuts" that can significantly impair data
interpretation later on. Knowing that, the purpose of each monitoring step
must be defined clearly before starting any field activities, Proper design of
monitoring programs before entering the field is absolutely vital to establish
the relevance and priorities for the sampling procedures.
Since 1995, UNIDO has been providing technical assistance to the small-
scale mining sector in developing countries. Through numerous projects
dealing with the introduction of cleaner technologies and mercury pollution
abatement, the Organization has assessed the environmental and health
Gtohaj Mercttry Proj eet —P rotocols for Ettvironmental and Health Assessntent
impacts of Hg pollution caused by artisanal gold miners, inter alia in
Venezuela, Ghana, and the Philippines. It is widely accepted that problems
associated with artisanal gold mining in dif'ferent developing countries are
similar in nature, As such, solutions need a globally consistent and
effectively coordinated approach in order to deal with these complex
problems on a local level, The GMP (Globa! Mercury Project) was initiated
by UNIDO in August 2002 to help demonstrate ways of overcoming barriers
to the adoption of best practices, waste minimization strategies and pollution
prevention measures that limit contamination of international waters. The
Project, funded by GEF and co-funded by UNDP and UNIDO, is
complemented by a suite of ongoing activities that are financed either
through the participating countries' resources and/or bilateral programs.
The main goals of the GMP are to:
~ reduce Hg pollution caused by artisanal miners on international
~aters.
introduce cleaner technologies for gold extraction and teach miners
how to use these technologies;
~ develop capacity and regulatory mechanisms within local
governments that will enable the sector to minimize Hg pollution;
~ introduce environmental and health monitoring prograins;
~ build capacity in focal laboratories to assess the extent and impact of
Hg pollution.
The monitoring component of the Global Mercury Project (GMP) has
specific goals, which are described in Objective 3 of the project proposal:
"identifv hotspots in proj etit demonstration sites, conduct geochemical and
toxicological stitdies and other field investigations in oi'der to assess the
extent' of environmental (mercu"r y) pollution in surrounding water bodies and
devi se intervention measures.
One key feature of the momtoring program should be that it is designed to
follow the evolution of Hg pollution in a mining area over time, To be
successful, the program must focus on investigating bioavailability and
bioaccumulation of I-Ig. Biota are the ultimate indicators providing direct
evidence that Hg in the environinent has become bioavailable and is being
bioaccumulated. This document highlights the relevance of samphng aquatic
biota and diminishes the importance of sampling water due to the low Hg
levels in solution. Evidence of bioaccurnulation must be obtained or
predicted, in order to evaluate the appropriate course of action. If impacts to
biota were not demonstrated at a contaminated site, then containment and
long-term inanagement would be more appropriate than other aggressive
Global Mercury Project —p rotocois for Lnvironmentai and Health Assessment iii
remediation measures, This, of course, is based on the acceptability to
regulators.
As such, the monitoring program should establish simple, replicable and
sustainable operational protocols for observing how Hg levels in different
environmental and biological samples change over time. These protocols
must then be transferred to environmental agencies, mining-related
institutions and researchers to ensure that these groups apply sound
techniques for sampling, sample preservation, transportation, analysis, etc.
An important objective of the monitoring steps of the GMP is the
identification of mining hotspots, which are sites with high concentration of
metallic Hg. Often, mercury has been dumped by artisanal miners, into or
near streams. There are also sites with the potential to become
environmental hotspots; these are sites where Hg has been transformed into
a more toxic and available form (i. e. methylmercury). Hotspots can have
dimensions of a few square meters to hundreds of square meters and are the
main sources of Hg dispersion into aquatic systems. Thus, they impact
thousands of people who may or may not be involved with the mining
activities, Identification and assessment of the risks posed by these hotspots
should be a main objective of the Environmental Assessinents.
Sampling procedures for such hotpots must be site-specific, taking into
consideration the characteristics of the mining activity; the biodiversity of the
region; the accessibility and availability of resources; risks; logistics; etc.
Therefore, these Protocols, designed for the GMP, do not provide many
details for such sampling. However, the Protocols do present the scientific
rationale behind the decisions on what must be preferentially sampled and the
inethodologies. The researcher conducting EEzHA must have a great deal of
flexibility to adapt these concepts to the field conditions and the available
budget. In EHAA, researchers must be careful not to create false expectations
among local stakeholders related to solutions regarding Hg pollution,
Environmental assessment is merely an initial step in addressing the issue by
identifying problems and proposing solutions. This is frequently not
understood by local stakeholders or by governmeni. regulators, who want to
see procedures implemented and problems solved as quickly as possible.
Jn terms of technical solutions, when a situation with Hg vapour exposure is
identified, such as when miners are burning amalgam in open pans, there are
a number of quick and simple solutions that can be implemented immediately
to reduce Hg exposure. These include the use of homemade retorts to recover
Hg, removing women and children from the amalgamation area and
discouraging the burning of amalgams in closed areas such as kitchens. These
simple measures can be brought to the attention of miners and other
Global lvjercnry Project —P rotocob for Environmental and Bealtb Asses. sment iv
individuals exposed to Hg easily, thus reducing the community's exposure to
Hg significantly. To limit exposure of individuals or families to MeHg, the
consumption of large ainounts of carnivorous tish should be avoided.
Instead, they should consume fish with lower MeHg concentrations or dilute
their meals with vegetables, when these are available.
There is considerable controversy as to whether or not therapies should be
discussed with Hg intoxicated people during a monitoring campaign. For
ethical reasons, UNIDO has adopted the approach to inform the local and
regional health care authorities when Hg intoxication problem is detected.
UNIDO's mandate is to provide assistance in eradicating pollution sources,
not to undertake active intervention. Although the organization understands
that the health conditions of affected communities must be considered,
medical intervention should only be undertaken by physicians operating
within organizations better qualified for this task than VN1DO.
This document gathers information from many scientific publications and
from the practical experience of the authors and their colleagues. Many
"hints" provided here have been discovered through trial and error on
projects not reported in scientific journals, for a number of international
institutions. This inforination is offered to facilitate the implementation of the
EHsleA Protocols and to assist researchers who are operating in difficult field
situations.
Global Mercury Proj ec( —P rotocols for Environmental and Health A.s sessmenr
Table of Co@tents
SUMMARY .
TABLE OF CONTFNTS V
LIST OF TABI. FS., IX
LIST OF FIGURES. . IX
ACKNOWLEDGEMENT.
IMPOR'I'ANT NOTE. Xl
PART I —F NVIRONMENTAL ASSESSMEN'I'. 12
1. 1. AMALGAMATION AND IVIFRCURY RFI.E ASES 17
1.1 . 1. Mercury Used by ASM. 18
Amalgamating . . 18
Cyan idation of Tailings . . 21
Removing Excess Hg. 23
Burning Amalgams . . . . .. . .. . . . . .. .. . .. . . 23
Recycling Mercury, 28
Melting Gold. , 28
The Hgi„, Au, ~„«q ratio . . 29
Other Important Aspects . . 34
1. 1.2 . Evaluating I lg Releases. 37
Sampling ASM Operations . . 37
1,2 . CHARACTERIZING CONTAMINATION AND POLLUTION . .. .. . . 39
1.3 . SOILS AND SEDIMENTS 42
1,3 , 1, Determining Soil and Sediment Background. . 46
Sampling Soils and Sediments I'or Background Determination. . . . .. . .. . .. . 48
1.3 .2 . Dispersed Contamination, 52
Atmospheric Deposition Rates 56
Atmospheric Deposition I'orms. 59
Sampling Soils and Sediments with Dispersed Hg Contamination . .. . .. . 60
1.3 .3 . Hotspots . 62
Sampling and Locating Mining Hotspots . . 64
Sampling Air in I lotspots. 69
Sampling and Locating Enviromnental Hotspots. . 70
1.3 .4 . Mercury Mobility. 75
Predicting Hg Mobility 77
Sampling to Establish Mercury Mobility 78
1.4 . WATFR. 80
Sampling Water. . . . 84
1, 5. ASSESSING MERCURY BIOAVAILAI31LITY 85
1.5 . 1. Using Sclcctive I xtraction to Assess Bioavailability. 85
1.5 .2 . Using Fish to Assess Bioavailability. 90
Standardizing Approach. 91
Impoundment F fleet „„„„ .. . . 95
Sampling Fish. 97
„,
Preserving Fish Samples„„„, 103
Bioassays 104
1, 5, 3. Using Invertebrates to Assess Bioavailability. 106
Sampling Attuatic Invertebrates. I I 0
Gloha/ Mercurv Project —P rofoeols for Environmental and Health Asse strnen/
1.5 .4 . Taxonomic Richncss and Abundance to Assess Bioavailability. . .. . , , . .. . , . I I I
I.S .S . Using Physico-chemical Variables to Assess Bioavailability . . . .. . . .. . . .. . . . . I I 2
Hurnosity, .. . . . . . I I 3
Water Conductivity, „. . . .. .. I i 3
Sediment pH„ .. . 113
Sediment Eh . . 114
Biomass, .. . . . .. I I 4
I'empcrature . . . .. . I ] 4
1.5 .6 . Using Humans to Assess Bioavailability . I I 4
Urine , I ! 5
Sampling Urine. . . .. . . I I 7
Crcatinine in Urine . . 118
Proteinuria in Urine .. . . . . I I 9
Blood. . . .. . . I I 9
Sampling Blood . I 20
I lair 'I 20
Sampling Hair . !23
1.6 . ANALYTICAL PROCEDURES. . , . . .. 126
1.6 . 1. Water. . . . . .. I 26
1.6 .2 . Sediment, „„, . .. . . . I 27
Digestion Procedures .. . . . . 127
Direct hfercury Analysis 128
Measurcmcnt of total Hg using CVAAS. 129
Measurement of total Hg using CVAFS . . . .. . I 3 0
Measurcmcnt of total Hg using ICP/MS, .„ . . .. „ . 13.0
Anab zing MeHg in Soils and Sediments. . . 131
1.6 . 3. Biota Tissue . . . .. . I 3 I
1.6 .4 . Urine, Blood and Hair I 3 2
1,6 , 5. Other Analytical Procedures. . . . .. . . I 3 3
1.7 . QUAI. ITY ASSURANCE/QLiAI. ITY CONTROL „„. I 3. 4
1.7 . 1. Precision . . 134
1.7 .2 . Accuracy. , . . . . . I 3 5
1.7 . 3. Method Detection Limit . . .. . . I 36
PA RT 2 —H EAL TH ASS F SS MENT . , 137
2, 1, HEAL'I'H El FECTS CAUSED BY IvIERCURY VAPOUR 139
Symptoms of Hg Vapour Exposure. . „„139
Health Problems of ASM Exposure to Hg Vapour. . . . .. I 4 I
25L HEALTH FFFFCTS CAUSED BY METHY'I. MERCURY 145
2, 2. 1. Iraq Tragedy. . . 145
2, 2, 2, The Minamata Outbreak. .. 146
„,
2.2 .3 . McHg Poisoning. .„ . . 147
Effects of Mel Ig o„n .th e Brain, .. . . 147
Main Symptoms, . . . .. .. . . . . . .. . . . I 4 7
Congenital EITccts of MeHg. . . .. . .„ . I 4 9
2.2 .4 . Low-level MeHg Fxposurc ] 50
2.3 2.. G3 .U 1I. DHEg LinIN UErSin eA ND RFFERENCE DOSES. „,. . . ., II 55 33
2. 3, 2, I lg in Fish. . .. . . .. I 5 3
2. 3.2 . Hg in Hair. . . . . . .. I 54
2.4 . SAMPLING FISH I'OR HEALTH ASSESSMFNT I 5 5