Data and information gaps
This chapter is intended to characterise the main categories of data gaps
identified for improved risk assessment and risk management with regard to
mercury. As such it does not attempt to give a full list of detailed data
gaps in the different fields of research.
National research and information needs
A number of countries have in their submissions to UNEP expressed a need
for establishing or improving their national “database” (i.e.
knowledge of and information on uses and emissions, sources of releases,
levels in the environment and prevention and control options) on mercury
and mercury compounds. Although the situation varies from country to
country, there seems to be a general need for information relevant to the
various elements of an environmental management strategy for mercury.
Also countries with a longer tradition of environmental management
of mercury have expressed the need to continue to expand their knowledge
base on mercury to improve risk assessment and ensure effective risk
management. Some of the needs
include, among others:
of national use, consumption and environmental releases of mercury;
of current levels of mercury in various media (such as air, air
deposition, surface water) and biota (such as fish, wildlife and
humans) and assessment of the impacts of mercury on humans and
ecosystems, including impacts from cumulative exposures to different
on transport, transformation, cycling, and fate of mercury in various
and evaluation tools for human and ecological risk assessments;
and information on possible prevention and reduction measures relevant
to the national situation;
awareness-raising on the potential adverse impacts of mercury and
proper handling and waste management practises;
tools and facilities for accessing existing information relevant to
mercury and mercury compounds at national, regional and international
building and physical infrastructure for safe management of hazardous
substances, including mercury and mercury compounds, as well as
training of personnel handling such hazardous substances;
on the commerce and trade of mercury and mercury-containing materials.
information exchange and national efforts to collect information
In principle, some parts of this information might be exchanged
nationally, regionally or internationally, as its relevance is often
universal, however, it might need to be “translated” into the context
of the individual country’s framework of traditions, economic and
industrial activities and political reality. This, in itself, demands a
substantial degree of priority, knowledge and funding.
The assessment process undertaken by UNEP through Governing Council
decision 21/5 and the data collected and presented in this connection
(reports, documents, web-page) in itself contributes to such information
exchange – other additional information exchange activities might also
be considered. No doubt, large amounts of basic knowledge on mercury have
been generated, and progressively more information is becoming globally
available thanks to national, regional and international efforts.
Furthermore, the speed of the information exchange is increasing as more
and more information on mercury and other hazardous substance becomes
available via the Internet.
Other parts of the information are country specific and would require
national efforts to research, collect and process the information
necessary to establish national action plans/strategies on mercury within
the context of their national environmental management scheme.
A number of
countries have developed strategies to promote research and information
generation activities to fill identified information gaps or generate
further information to support their mercury risk assessment and
management activities. A few examples include the Mercury Research Strategy issued
in September 2000 by the US
EPA (sub-5-gov) and the COMERN (Collaborative
Mercury Research Network) research programme on the impacts of atmospheric
mercury deposition on large scale ecosystems in Canada, supported by the
Canadian government (sub-5-ngo). A
number of national and regional mercury action plans also contain sections
describing concrete activities to fill data and information gaps.
Data gaps of a general, global character
addition, although mercury is probably among the best-studied
environmental toxicants, there are data gaps in the basic understanding of
a number of general, global issues relevant to mercury.
on submitted information and the compilation and evaluation hereof, a
possible division of current data gaps of global relevance on mercury
could be as follows (not in order of priority):
and quantification of the natural
mechanisms affecting the fate of mercury in the environment, such
as mobilisation, transformation, transports and intake. In other
words, the pathways of mercury in the environment, and from the
environment to humans.
and quantification – in a global perspective – of the human
conduct in relation to mercury releases, and the resulting human
contributions to the local, regional and global mercury burden. In
other words, the pathways of mercury from humans to the environment.
of how and to what degree humans, ecosystems and wildlife are adversely
affected by the current mercury levels found in the local,
regional and global environment. In other words, the possible effects,
number affected, and the magnitude and severeness in those affected.
basic understanding has been established for all three categories
mentioned above, based on about half a century's extensive research on the
impacts and pathways of mercury. However, in a number of areas, further
research is needed to provide new information to improve environmental
modelling assessments and modern decision-making tools.
of origins, pathways and impacts of mercury
In order to manage environmental toxicants like mercury efficiently and
cost-effectively, a substantial level of quantification of origins,
pathways and impacts is necessary. The question of which level of
certainty of evidence is considered required as a basis for abatement
actions is, however, basically political – a set of priorities in the
span of public health, environmental quality and socio-economic
possibilities. The traditions and political priorities on these aspects
vary among countries and regions, and develop over time.
However, as an example, Canada expressed in their comments to the first
draft of this report (comm-24-gov):
there are numerous areas
where additional knowledge is required, for example in the areas of
biochemistry, atmospheric sciences, hydrology, toxicology/epidemiology,
monitoring strategies for mercury levels in biota, and the collection of
information on mercury levels in fossil fuels. However, while
it is important to be aware of outstanding questions, the existing
evidence clearly demonstrates that there are risks to the environment and
human health associated with mercury exposure.
Therefore, it is not realistic to delay the process of the
assessment and options development until we have all the answers.”
of identified data gaps
The following sections provide a summary of the types of data gaps
mentioned in submissions and comments to the first draft of this report,
as well as gaps identified in the preparation of this report. For more
details, see references given below.
Examples of data gaps on natural mechanisms affecting the fate of
studies of natural emissions of mercury would be useful in order to
minimise uncertainties in their quantification and describe better the
relative importance of human mercury contributions. In particular,
information is needed on the location of main natural emission areas
and quantification of seasonal and annual variations of the emissions
in addition to the total amounts, as well as separation of area
sources (e.g. from areas with mercury-mineral containing soils and
bedrock) and point sources (e.g volcanoes and fumaroles). Mercury is
also emitted from ocean surfaces and the natural component of these
emissions cannot be distinguished from re-emissions of previously
deposited mercury. In this case, the total emissions to the atmosphere
should be determined. In all cases, determination of speciation of
mercury emitted from natural sources is of importance, including
identification of elemental mercury, oxidised gaseous mercury and
methylated mercury (i.e. mono- and dimethylmercury) (see for example
submission from Canada, sub-42-gov).
studies would be useful in order to improve the understanding of
transport, transformation and fate of mercury in the atmosphere and in
aquatic and terrestrial media, with particular focus on:
Improvement of the quantitative understanding of the dynamics of
mercury transformations and deposition processes in the atmosphere,
including the Polar Mercury Depletion Events and oxidation/reduction
processes in the free troposphere, laboratory and field investigations
of oxidation/reduction processes, dry deposition and gas-liquid exchange
Determination of processes that control the mobilisation/immobilisation
of mercury in soils and sediments, with main focus on leaching of
mercury and methylmercury from forest soils to aquatic systems;
Quantification of methylation/demethylation processes in aquatic
ecosystems with specific focus on Arctic and coastal ecosystems and
processes where oxidised mercury is reduced and released to the
atmosphere and identification of the main pathways of methylmercury
uptake in aquatic foodchains, with focus on Arctic and coastal
Development and refinement of models describing chemical
processes, dispersion and long-range transport of mercury, with special
focus on hemispherical and global scale models, in order to facilitate
quantitative descriptions of the global atmospheric cycling of mercury;
and development of ecosystem models for mercury including mobility and
bioaccumulation in terrestrial and aquatic ecosystems;
Encouragement of technology transfer and international
cooperation on standardising sampling and analytical methods for mercury
studies of methylation, biomagnification and other processes and
interactions in the food webs would be useful in order to describe
better (e.g. in quantitative models) the links between human releases
of mercury and observed concentration levels and impacts on humans,
ecosystems and wildlife, (see for example submissions of Canada
(sub-42-gov), COMERN (sub-5-ngo), Switzerland (sub-38-gov), Germany
(sub-57-gov) and Thailand (sub-53-gov).
studies of chemical reaction constants and other mechanisms affecting
the transformation and fluxes of mercury in and between gaseous,
liquid and solid phases in the atmosphere, as well as between the
atmosphere and the aquatic and terrestrial environmental compartments,
would help to improve modelling of local, regional, hemispherical and
global atmospheric transport of mercury, and better understand the
global mercury cycle, (see for example submission of Italy/EU,
measurements and assessments of re-emission of formerly deposited
mercury from land and water surfaces might be needed to improve
understanding of the global mercury cycle, including atmospheric long
range transport and the relative importance of anthropogenic
contributions, as well as enhancing possibilities for modelling and
monitoring changes due to emissions reductions, (see for example
submission of Italy/EU, sub-52-gov).
studies of the evidence of the accumulated historical mercury
contributions of humans to the environment, would be useful in order
to describe better the relative importance of human impacts, (see for
example submission of Canada, sub-42-gov).
monitoring of the role of dry deposition of mercury would be useful in
order to gain a better understanding of the relative contribution of
wet versus dry deposition.
Examples of data gaps on human conduct in relation to mercury
improvement and updating of assessments of global anthropogenic
consumption, mobilisation, flows and releases of mercury (including
atmospheric emission inventories, releases from waste treatment
releases to aquatic environments etc.) would be useful in order to
give a more complete picture of the situation and a better basis for
selecting – on a global basis – which human sources should be
addressed (and how), if reduction of human mercury releases are
(see for example section 6 and 7, submissions of the European
Commission (sub-40-gov), Italy/EU (sub-52-gov), Switzerland
(sub-38-gov), and comments from USA (comm-24-gov).
of expected changes in global consumption and corresponding supply of
mercury for different possible prevention/reduction scenarios would be
useful in order to give a basis for decisions on management of supply
(production, recycling and stocks management), in case this is
prioritised, (see for example submission of the Nordic Council of
it has been possible to assemble a reasonably complete picture of
commodity stocks and flows among industrialised countries, the
decreasing economic importance of mercury has been accompanied by a
corresponding decline in public availability of production and use
information. Moreover, an increasing share of mercury production and
use occurs in developing countries, and as such, is little reported.
Finally, many countries are unaware of flow analysis techniques.
Specific data gaps, including those for mercury production and use,
Annual basic production and use figures to allow for monitoring
of programme success in reduction efforts, including such information as
compiled by USA Geological Survey's annual "Mineral commodity
A baseline economics study of primary virgin mining of mercury to
provide insight into price-responsiveness of mines. Examples of
information to be obtained include: legal status, ownership, relevant
environmental regulation, per-unit cost of production, the nature and
extent of public subsidies and annual production and sales since 1990;
A periodic inventory of uses to guide future demand-reduction
efforts, including an exhaustive list of specific uses (products and
processes) and quantitative estimates of current use and
characterisation of future demand for major end-use categories;
A periodic inventory of non-market demand factors to support
future demand projections, including a list of mandatory
A baseline survey of artisanal mining, including the quantity of
gold mined, the number of miners and the quantity and rate of mercury
Available techniques to perform materials flow analyses (MFA, SFA)
in all industrial sectors need to be transferred and applied
of emission inventories for anthropogenic emissions, including
speciation of mercury, would be useful. Special attention should be
paid to diffuse emissions from handling of elemental mercury (e.g.
artisanal gold mining), household and uncontrolled waste incineration,
as well as improvement of data from main point source categories
(industries handling mercury, waste
incinerators and power plants using fossil fuel).
studies of mercury content in fossil fuels (coal, natural gas and
petroleum) and the chemical and physical mechanisms and combustion
conditions that influence mercury in a combustion system would be
useful in order to obtain a better understanding of the contribution
of fossil fuel combustion to the global mercury cycle and to determine
effective approaches to reduce emissions from this source. In
addition, it would be useful to imporive emission inventories for
major anthropogenic sources with emphasis on feedstock (e.g. coal),
process configuration (e.g. boiler design), emission control design
and operation, and by-product use/disposal.
and demonstration of integrated multi-pollutant (SO2, NOx,
particulate material and mercury) control technology and continuous
emission monitors would be useful.
of information on good practices in prevention and control technology
for cement production, conventional and artisanal mining,
metallurgical industries and chlor-alkali plants would be useful for
studies to develop commercially viable substitutes for those mercury
product applications that still remain would be useful in order to
reduce (and eliminate) intentional use of mercury in products and
ultimately remove mercury from the waste stream.
of a product substitution manual to be made available to many
countries would be useful.
of economic and social burdens and benefits of different possible
prevention/reduction scenarios for mercury would be useful in order to
give a better basis for selecting on a global basis which human
sources should be addressed, if reduction of human mercury releases
research on the interim and definitive storage of excess mercury and
mercury-bearing waste would be useful in order to be able to
permanently remove surplus quantities of mercury from society. Such
storage solutions need to be monitored and retrievable, and should
assure that the repository is maintained in a way that minimises
emissions by all routes to the greatest extent possible. The transfer
of mercury from society to such repositories must be conducted under
occupationally safe conditions.
Examples of data gaps on adverse effects of current mercury levels
of the understanding of dose-response relationships for methylmercury,
elemental and inorganic mercury and their dependence on individual
vulnerability, whether due to life-stage, nutrition, or other factors
would be useful. In regard to methylmercury, information gaps include
the possible impact on cardiovascular disease and mortality.
research on the potential for health impacts of dental amalgam and
vaccine additives containing mercury compounds would be useful.
and expanded monitoring of mercury concentrations in human hair and
other relevant human samples would be useful in order to allow better
definition of populations at risk from increased exposure. Such
monitoring may also be used as a tool for prioritizing prevention
actions on a local scale.
of the understanding of the effects of co-exposure to different
mercury species (and via different exposure routes) on dose-response
relationships for humans would be useful.
studies to improve the understanding of which – and how serious –
ecotoxicological effects mercury currently has on different types of
ecosystems and wildlife, in a global perspective, would be useful. For
example, a growing body of evidence suggests that certain highly
exposed wildlife species are at risk from exposure to mercury through
consumption of contaminated fish and shellfish. Key data gaps include
an improved understanding of toxicological effects and ecological
impacts of methylmercury on various species; interaction of mercury
with other chemical and non-chemical stressors on ecological
receptors; and ecological risk assessment methods.
of practises for international coordination of monitoring of various
environmental media would be useful.
of environmental benefits and burdens of different possible
prevention/reduction scenarios for mercury would be useful in order to
give a better basis for selecting – on a global basis – which
human sources should be addressed, if reductions of human mercury
releases are prioritised (relates also to the issue of human conduct
in relation to mercury).
Future use of information
collected for the Global Mercury Assessment
As mentioned several times in this report, a vast material has been
submitted for use in this process and a network of contacts at national,
regional and international levels have been established.
Besides the benefit already derived from this material, it might
also form part of a basis for further elaboration on several of the issues
mentioned above, as well as other issues relevant to the global
environmental implications of mercury, if such work would be deemed
Development of Policy Tools
On the basis of the summary provided in previous sections of this report
on the complexity of chemical and physical mechanisms involved in the
mercury cycle, one may wish to ask several questions, including the
following: (see also Pirrone 2001; Pirrone et al. 2002) What are the qualitative and quantitative
relationships between atmospheric input, deposition and mercury in aquatic
environments? Is it possible to establish a deposition limit for mercury
in order to regulate its emissions to the atmosphere? Do we know the
relationship between the flux of mercury entering surface waters and the
level of mercury (methylmercury) found in fish? Is it possible to evaluate
the response time of the marine ecosystem in relation to changes in
atmospheric emissions? Are any regional/hemispherical modelling frameworks
validated and tested for assessing temporal and spatial patterns of
mercury deposition to marine waters and its subsequent accumulation in the
fish and ultimately its impact on the food chain?
To help answer these questions and to assist the development and/or
implementation of international strategies aiming to reduce the impact of
mercury on human health and the environment, there is a need to develop
policy tools that would help policy makers and different type of users and
stakeholders to select the most cost-effective strategies.
an example, in Europe the Directorate General (DG) for Research of the
European Commission is supporting mercury research programmes (i.e.,
MERCYMS) aimed to develop integrated modelling tools based on the concept
of the Drive-Pressure-State-Impact-Response (DPSIR) framework, which has
been used already as basis for the European Air Quality Directive on
Ozone. Similar exercises
aimed to develop integrated modelling tools are underway also elsewhere
(i.e. USA, Canada).
10.1 provides a conceptual DPSIR for mercury pollution reduction and
control, as described by DG Research, where it is shown how our
understanding of pressure factors interact with other areas of
environmental knowledge such as impact assessment and monitoring (State),
economic activity (Driver) and effective environmental policy (Response).
A better assessment of a spatial
resolved emission inventories play an important role in assessing the
effects of anthropogenic activities on terrestrial and aquatic
environments. The principal human demands for i.e. energy, transportation
and food may be regarded as the "Drivers" for the production of
mercury emissions to the ambient air. In order for an economy to continue
to develop in a sustainable way, these sources of pollution must be
managed. To do this we need to understand the "Impacts"- i.e. what types of pollution affect which parts of the
environment or human health, and to what extent they do so. To decide
whether action is necessary it is also helpful to know the
"State" of the environment i.e.
evaluate whether the levels in the environment exceed those which will
cause environmental harm. In
taking appropriate action we must be able to respond in a focused way to
prevent, control and reduce pollution while avoiding larger-scale damage
to economic development. Emission inventories provide policy makers and
the public with an understanding of the key polluting sources or the
"Pressures", how these sources have developed with economic
growth and how they are likely to contribute to pollution in the future.
This understanding is essential for a focused "Response" to the
problems associated with mercury pollution and to meet the demands of
sustainable development. The
Policy Response may refer to socio-economic scenarios with different
Targets of mercury pollution control (i.e. BAU: Business as usual scenario; POT: Policy target
scenario; DG: Deep green scenario,).
Like mentioned in section 10.2 above, initiation of policy actions does
not always require a full, detailed understanding of all elements of the
of a conceptual Driver-Pressure-State-Impact-Response (DPSIR) framework
aimed to control and reduce the risk for human health and the environment
mercury exposure. BAU: Business as usual scenario; POT: Policy
DG: Deep green scenario. Source:
Project funded by the European
Commission – DG Research. Details can be found at