Methyl mercury in fish cause for concern
Dr.
Robin Anderson
For many of Labrador’s Innu population, fresh water fish has long
been a dietary staple. However, an increase in methyl mercury levels in
some species of fish found in the lakes and reservoirs of traditional
fishing grounds could be potentially harmful to the health of those who
consume these fish. One cause of the increase of mercury in remote Arctic
and Atlantic Canada ecosystems may have resulted from long range airborne
transport and deposition of mercury.
“Burning of fossil fuels for long range transport of mercury through
the air and deposition is a cause of concern for all northern environments,”
said Dr. Robin Anderson, an adjunct professor, Biology, at Memorial and
a marine habitat research scientist with the Environmental Science Branch
of Fisheries and Oceans. She is one of numerous scientists contributing
to the Collaborative Mercury Research Network (COMERN). COMERN is an international
group of researchers lead by Dr. Marc Lucotte, Université du Quebec
à Montréal, hoping to improve general understanding of mercury
in ecosystems and the risks to those who eat fish.
“Cold-fired generating plants in the U.S. and other industrialized
countries send toxic chemicals such as mercury into the upper atmosphere
and they are then moved towards the poles via winds and atmospheric movement,”
explained Dr. Anderson. “The creation of reservoirs can also result
in increased mercury levels which then will contaminate the aquatic food
chains for certain periods of time. Because mercury is bio-concentrated
up the food chain the highest levels are found in the predators at the
top of the food chain, such as pike and lake trout at the top.
“One of the objectives of this study is to provide the data that
is necessary to back up requests to do something about these emissions.
There are ways mitigating these emissions such as better scrubbers, use
of cleaner coal, and so forth.”
There seems to be only limited effects of mercury on cold blooded animals
(fish) and then at relatively high levels, explained Dr. Anderson, and
it tends to have a greater effect on warm blood animals – humans
are much more sensitive to lower doses.
“It’s a neurological toxin and therefore can affect humans in
a number of ways, the subtlest symptoms tend to be questions of fine motor
control, such as inability to thread a needle and intellectual capabilities.
The more overt symptoms with serious poisoning are trembling, mental retardation,
motor control problems of a general nature and even death,” Dr. Anderson
said.
The objective of the study is to determine current mercury levels of freshwater
fish in northern Labrador. This data will be compared with previous data
to determine if mercury levels are increasing in the fish of this area.
A four-year fieldwork program will be carried out by scientists with the
aid of Innu co-researchers. Preliminary results of each year’s fieldwork
will be reported to local communities, providing an opportunity for local
input into the sample sites selection. The final results will be publicized,
and presentations made to the Labrador Innu communities of Sheshatshiu
and Davis Inlet and to the scientific community.
“The research team has been building a strong partnership with the
Innu nation and making sure that all the information is available up front,”
said Dr. Anderson.
The COMERN network felt it was important to look simultaneously at environmental
health and the impact of these environmental changes on the human health
of populations that depend on fish. COMERN researchers will also carry
out research on the impact of human health. The network made up of 34
institutions and collaborators was awarded $12.6 million from NSERC in
May of 2001 and will be looking at mercury levels in numerous ecosystems
across Canada.
Dr. Anderson is quick to point out that this study is not meant to frighten
people from eating fish.
“Mercury is a naturally occurring chemical and is found in everything
in very low levels,” explained Dr. Anderson. “The only concern
is when it gets to be a high level and people focus on eating fish with
those high levels. Fish is still a good source of protein and has a balance
of amino acids. Its high in Omega 3 fatty acids other beneficial chemicals
and low in fat. The message is ‘don’t stop eating fish,’
just adjust your fish preferences if need be.”
