industry and environment - DTIE

Chemicals management
important elements in developing an appreciation
of the risk posed to the Canadian environment by
mercury and its organic compounds. 3 Environmental
monitoring is common in areas where
methylation is known to occur, such as partially
acidified watersheds, watersheds with large wetlands
high in dissolved organic carbon, and reservoirs.
Loons, 4 seabirds, Arctic marine mammals
and fish are frequently surveyed. Data reveal that
different fish species generally contain different
levels of mercury, with predators like lake trout,
walleye and northern pike containing higher levels
than forage feeders like cisco and whitefish.
The reasons why there are different levels in different
species are not yet clear and are the subject
of ongoing investigation. Other factors being constant,
mercury contamination of fish in smaller
lakes tends to be higher than that of those in larger
lakes. One possible reason is that smaller lakes
tend to be warmer, a factor that increases methylation
of mercury.
Canada has established and maintains national
and regional databases that identify elevated levels
of metals, including mercury in various media (air,
water, soil, biota). In addition, there are numerous
provincial initiatives including databases for
mercury levels in fish. 5
Monitoring occurs in freshwater bodies and in
sediments. It has become evident from sediment
core profiles that strong regional mercury accumulation
gradients exist.
However, the presence of inorganic mercury in
sediments needs to be correlated with levels of
methylmercury in the food chain, as the mere
presence of mercury does not explain how it enters
the food chain.
One recently discovered mechanism, seemingly
unique to the Arctic, relates to the polar sunrise
each spring. Since 1995 researchers have monitored
a drop in the concentration of gaseous elemental
mercury over the period from the first
sunrise in the spring until snowmelt. It seems that
elemental mercury becomes oxidized to reactive
mercury, which is then deposited on the snow;
snowmelt is the main source of freshwater for
most Arctic landscapes. More research is needed
to determine if and how this reactive mercury
becomes bioavailable to terrestrial and aquatic
ecosystems.
In the Arctic, where consumption of fish and
traditional game food such as seals, toothed
whales, caribou and moose is high, mercury exposure
in some communities 6 exceeds the Health
Canada and World Health Organization (WHO)
tolerable daily intake level. 7 In these communities
there is growing awareness of the potential risks to
health from a diet of mercury-contaminated game
food.
Human health considerations are a key factor
underlying Canada’s initiatives aimed at limiting
the release of mercury to the environment. However,
given that mercury is ubiquitous in the natural
environment, the routes of exposure to
humans are complex. They can include mercury
vapour (from inorganic mercury compounds) and
organic methylmercury.
Programmes, policies and guidelines
for risk management of mercury
Canada has federal legislation, regulations and
guidelines relevant to the control or reduction of
mercury
◆ in air;
◆ in fresh and drinking water;
◆ in waste effluent;
◆ during marine disposal;
◆ at contaminated sites;
◆ during transportation as product or waste;
◆ in consumer products;
◆ in pest control products;
◆ during occupational exposure.
In addition (and as Canada is a federation made
up of ten provinces, each with its own constitutional
authority), federal regulations are supplemented
by provincial acts, regulations and
guidelines covering liquid effluent, drinking water
and emissions from industrial sources.
The Canadian government has established a
process involving Health Canada, Indian and
Northern Affairs Canada (INAC), the Canadian
Food Inspection Agency (CFIA), Fisheries and
Oceans Canada and Environment Canada (EC)
implementing statutes, regulations and departmental
mandates to protect the health and environment
of Canadians. Specifically, Health
Canada establishes standards for the amount of
mercury humans may consume without adverse
health effects. Environment Canada’s mandate
includes the preservation and enhancement of the
quality of the natural environment, including
water, air and soil quality. INAC ensures that
northern communities 8 are aware of the health
hazards of consuming traditional foods that may
contain higher levels of mercury. CFIA deals with
the commercial inspections of fish products before
they are sold on the Canadian market. Fisheries
and Oceans maintain inland fisheries.
Provincial governments have the responsibility
to perform monitoring and testing programmes
which include sampling fish from a variety of lakes
and rivers, analyzing fish samples for contaminants,
issuing fish consumption advisories, if
needed, and informing the public of these advisories.
It is also the responsibility of provincial
governments to issue fish advisories (recommendations
against eating fish from specific lakes),
although recreational anglers can continue to
catch fish under a “catch and release” philosophy.
The Canadian, provincial and territorial governments
and Aboriginal peoples work in partnership
to monitor exposure of adults and
children, particularly those who consume the
greatest quantities of fish, marine mammals and
game food (that is, those animals that feed on
fish). While the majority of this work is centred in
the Canadian North, it also includes southern
communities with a higher than average consumption
of country foods. While monitoring in
the past relied on blood mercury levels, researchers
now prefer hair analysis as a more accurate
method of monitoring continuous exposure. 9
Since the neurotoxic effects of methylmercury are
most likely irreversible, it is important to know
the peak exposure of an individual.
Canada’s regulatory approach to
minimizing mercury’s environmental
and health risks
To minimize the environmental and health risks
from toxic substances, the federal government has
promulgated a range of policies and regulations,
which are described below.
Minerals and metals policy of the government
of Canada
Canada’s policy on the sustainable development
of minerals and metals, 10 adopted in 1996, is
based on
◆ life-cycle management;
◆ risk assessment and risk management;
◆ safe use;
◆ science and technology;
◆ recycling.
Life-cycle management is an essential part of
environmental stewardship. It provides the overarching
framework for realizing the policy’s other
aspects and is closely linked to risk assessment and
the principle of safe use. In managing mineralsand
metals-related health and environmental
issues, the principle of life-cycle management, for
both processes and products, plays an essential
role.
Inherent in the life-cycle management of metals,
including that of mercury, is the application
of risk assessment and risk management processes.
Risk assessment estimates the degree and likelihood
of adverse effects resulting from exposure to
a substance from a process or product. Risk management
is the process of deciding what to do
about an assessed risk, taking into account the
results of the risk assessment and economic, social
and legal factors.
The Safe Use Principle guides the development
of regulatory or non-regulatory strategies to manage
the risk, based on the results of the risk assessment
for a particular product during production,
use, re-use, recycling or its ultimate return to the
environment. By adhering to the Safe Use Principle,
governments will ensure that society continues
to benefit from minerals- and metals-related
products, such as energy-saving fluorescent lights,
while protecting human health and the environment
in a manner consistent with sustainable
development.
Canada’s minerals and metals policy recognizes
the important role of science and technology in
the achievement of sustainable development. At
the present time, the Canada Centre for Mineral
and Energy Technology (CANMET) is the lead
laboratory for the OECD’s validation study of a
transformation dissolution protocol (T/DP), data
from which will be used in the United Nations
Globally Harmonized System of Classification
and Labelling (GHS) for the hazard identification
and classification of metals and sparingly solid
metal compounds with respect to the aquatic
environment. 11 The T/DP may also be extended
to alloys. In addition, the T/DP and the GHS
could be applied to mercury and its compounds.
Recycling is a key component of sustainable
development, offering environmental as well as
economic benefits. To achieve recycling’s full
40 ◆ UNEP Industry and Environment April – September 2004