Canadian Arctic Contaminants Assessment Report II

150 Pages·2003·2.56 MB·English

N O RT H E R N C O N TA M I N A N T S P RO G R A M
C A C
ANADIAN RCTIC ONTAMINANTS
ASSESSMENT REPORT II
HUMAN HEALTH
Chukchi Sea
Arctic Ocean
Beaufort Sea
Sachs Harbour
(Ikaahuk)
Old Crow Tuktoyaktuk
Aklavik Inuvik
(Ak∏arvik) (Inuuvik)
Holman
Fort McPherson Paulatuk (Uluqsaqtuuq)
(Teet∏’it Zheh) Tsiigehtchic
(Paulatuuq)
(Tsııgehtshık)
Colville Lake
Fort Good Hope (K’áhbamítúé)
Dawson (Rádeyılıkóé)
Beaver Creek Keno Hill Kugluktuk (CIaqmalburkitduguet iBaqay)
Mayo Norman Wells (Coppermine)
Pelly Crossing (T∏egóhtı )
Umingmaktuuq
Carmacks Faro Ross River Tulita (DDéélliı nnee)
(Tulít’a) Qinguaq
Haines (Bathurst Inlet)
Junction Whitehorse
Wrigley Rae Lakes
(Pedzéh Kí) (Gametì) Snare Lakes
Carcross (Wekwetì)
Teslin
Wha Ti
(Wha T ) Rae-Edzo (Behchokò-Edzo)
Watson Lake Fort Simpson (¸íídlı Kúé)
Nahanni Butte (Tthenáágó) Je(Tanth Meka’érihed Réilvı )er Yellowknife (Sò˛ mbak’`e)
Fort Providence Lutselk’e
Fort Liard (Zhahtı Kúé) (¸útsëlk’é)
Hay River Fort Resolution
(Xát∏’odehchee) (Denínu Kúé)
Fort Smith
(Tthebacha)
Alert
Ausuittuq
(Grise Fiord)
Resolute
(Qausuittuq)
Ikpiarjuk/Tununirusiq Mittimatalik
(Arctic Bay) (Pond Inlet)
Kangiqtugaapik
(Clyde River)
Baffin Bay
Taloyoak Igloolik Qikiqtarjuaq
Sanirajak (Broughton Island)
Uqsuqtuuq Kugaaruk (Hall Beach)
(Gjoa Haven)
(Pelly Bay)
Pangnirtung
Naujaat
(Repulse Bay)
Iqaluit
Kinngait
Qamanittuaq (Baker Lake) Salliq (Cape Dorset)
(Coral Harbour)
Kimm irut
(Lake Harbour)
Igluligaarjuk (Chesterfield Inlet)
Kangiqliniq (Rankin Inlet) Ivujivik Salluit Kangiqsujuaq
Tikirarjuaq (Whale Cove)
Quaqtaq
Akulivik
Kangirsuk
Arviat
Puvirnituq Aupaluk
Kangiqsualujjuaq
Tasiujaq
Nain
Hudson Bay Kuujjuaq
Inukjuak Hopedale
Makkovik
Postville
Rigolet
Umiujaq
Sanikiluaq
Happy Valley/Goose Bay
Kuujjuarapik
Cover photos: INAC/Jennifer Baizana and ITK/Eric Loring
Published under the authority of the
Minister of Indian Affairs and Northern Development
Ottawa, 2003
www.ainc-inac.gc.ca
1-800-567-9604
QS-8525-003-EE-A1
R72-260/2003-4E
0-662-33469-8
© Minister of Public Works and Government Services Canada
TOXIC SUBSTANCES IN THE ARCTIC
AND ASSOCIATED EFFECTS -
HUMAN HEALTH
Contributors:
This report is based on contributions from a number of individuals.
In some cases, these contributions are supplemented by additional information
from related studies in the scientific literature and have been edited to ensure
a coherent assessment report. The Northern Contaminants Program, Department
of Indian Affairs and Northern Development, would like to thank the following
authors for their contributions in their respective areas of expertise:
GNWT/NWT Archives/B. Harnum
Authors and Editors:
J. Van Oostdam1, S. Donaldson, M. Feeley, N. Tremblay
Authors:
D. Arnold, P. Ayotte, G. Bondy, L. Chan, E. Dewailly, C. Furgal, U. Gill,
S. Kalhok, H. Kuhnlein, E. Loring,
G. Muckle, E. Myles, O. Receveur, Y. Stokker, B. Tracy
Contributors:
J. Bailey, S. Bernier, H. Bilrha, S. Bruneau, F. Dallaire, S. Jordan, D. Pereg, R. Roy
Acknowledgements
The list of people who have been involved in these environmental contaminant,
dietary and health effects research studies is extremely long, from researchers to
contaminants coordinators in each region, to community health workers, to dietitians,
to nurses, to mothers and community residents. All deserve a great round of
thanks, as without their efforts and contributions of new and ground breaking
research and cooperation we would have very little to present in this report.
The authors would like to thank P. Bjerregaard, D. Villeneuve and G. Egeland
who reviewed an earlier draft of this report.
1 Author to whom correspondence should be addressed. Health Canada,
Safe Environments Program, Management of Toxic Substances Division,
Rm B233, Environmental Health Centre, Tunney’s Pasture, AL 0801A2,
Ottawa, ON, Canada, K1A 0K9
Executive Summary
The Northern Contaminants Program (NCP) was estab- Aboriginal perspectives on food and health
lished in 1991 in response to concerns about human
Traditional/country foods are an integral component of
exposure to elevated levels of contaminants in fish and
good health among Aboriginal peoples. The social, cultural,
wildlife species that are important to the traditional diets
spiritual, nutritional and economic benefits of these foods
of northern Aboriginal peoples. Early studies indicated
must be considered in concert with the risks of exposure to
that there was a wide spectrum of substances — persistent
environmental contaminants through their consumption
organic pollutants, heavy metals, and radionuclides —
of traditional/country foods. Traditional/country food is
manyof which had no Arctic or Canadian sources, but
an economic necessity for many Aboriginal peoples. The
which were, nevertheless, reaching unexpectedly high
hunting, fishing and gathering of traditional/country food
levels in the Arctic ecosystem.
and the subsequent sharing of these items with individuals
Under the first phase of the NCP (NCP-I), research was throughout the community are social activities bringing
focussed on gathering the data required to determine the together individuals, families and generations. In this
levels, geographic extent, and source of contaminants in way, traditional/country foods form and maintain an
the northern atmosphere, environment and its people, important social and cultural fabric among individuals
and the probable duration of the problem. Results gener- which supports community health and well-being.
ated through NCP-I were synthesized and published in
1997 in the first Canadian Arctic Contaminants Health determinants
Assessment Report(CACAR-I).
Determining the adverse human health effects due to the
In 1998, the NCP began its second phase (NCP-II), presence of contaminants in traditional/country foods is
which will continue until March 2003. NCP-II focussed very difficult as many factors contribute to the health of
upon questions about the impacts and risks to human an individual and in fact contaminants may only play a
health that may result from current levels of contamination modest role in determining an individual’s health status.
in key Arctic food species as well as determining the Factors such as lifestyle (e.g., alcohol consumption,
temporal trends of contaminants of concern in key smoking, and substance abuse), diet, socioeconomic
status and genetic predisposition are important health
indicatorArctic species and air. It addressed these issues
determinants that need to be considered when evaluating
under a number of subprograms: human health; moni-
the results described herein.
toring the health of Arctic peoples and ecosystems and
the effectiveness of international controls; education and
Contaminant exposure
communications; and international policy.
Persistent environmental contaminants such as PCBs,
The priority areas in the human health subprogram dur-
toxaphene, DDT and mercury biomagnify and bioaccumu-
ing NCP-II included: exposure assessment, toxicology,
late in the food chain. Levels of organochlorine contami-
epidemiology, and risk and benefit characterization. The
nants in human tissue in the Arctic are considerably higher
key objectives of this, the human health technical report
than those in southern Canadians, reflecting the greater
in the CACAR-II series, are to summarize the knowledge
consumption of food species at the top of long food chains.
produced since the first CACAR on human exposure to
and possible health effects of current levels of environ- Traditional/country food use by women and men 20–40
mental contaminants in the Canadian Arctic, and to years of age is highest in Inuit communities, followed by
identify the data and knowledge gaps that need to be Dene and Métis of the NWT and then First Nations
filled by future human health research and monitoring. people of the Yukon. Age and gender are factors influencing
The CACAR-II series consists of a Highlights report and traditional/country food use, with men having higher
four technical reports: human health, biological environ- average intakes than women, and traditional/country food
ment, physical environment and knowledge in action. consumption increasing with age. Continued monitoring
i
and assessment of the frequency of consumption of lichen caribou human food chain and have been
traditional/country foods in a limited number of Dene present in the Arctic environment for thousands of years
and Métis, First Nations, and Inuit communities is at more or less the same concentrations as found today.
needed to identify any significant changes in consumption Currentestimates of polonium exposure would give a
patternsand those with highest exposures. radiation dose of 3–4 millisieverts/year (mSv/yr) to a high
consumer of caribou meat over and above normal back-
Human contaminant levels ground radiation exposure of 2–3 mSv/yr.
Inuit mothers have oxychlordane and trans-nonachlor levels
Trends in traditional/country food dietary
that are 6–12 times higher than those in Caucasians, Dene
intakes and contaminant exposures
and Métis, or Other mothers, with Baffin Inuit mothers
having the highest levels. Similar patterns were observed For Canadian Inuit, intakes of traditional/country food
for PCBs, HCB, mirex and toxaphene. The monitoring do not seem to have significantly changed in the last 20
of organochlorines in human tissues does not have a long years. Surveys of dietary intake in one Inuit community,
history in the Canadian Arctic, and continued monitoring Qikiqtarjuaq (Broughton Island), Nunavut have shown
of tissue levels is needed to determine contaminant trends. that mercury exposures were similar in 1987–1988 and
Special attention should be given to oxychlordane, trans- 1999, thus implying little change in dietary pattern or
nonachlor, HCB, mirex, toxaphene and PCBs, especially mercury concentration in food. However, reported intakes
among the Inuit of Nunavut and Nunavik. of the organochlorines were somewhat higher in 1999,
particularly among the highest users (95thpercentile).
Recent research has revealed significantly higher levels
Focussed monitoring of traditional/country food consump-
of mercury in the maternal blood of Inuit women
tionin specific Arctic communities through surveys of
when compared to Caucasian, Dene and Métis or the
dietary intakes of environmental contaminants, such as
Other group. Nunavik and Baffin Inuit have higher
organochlorines (e.g., PCBs, chlordane, toxaphene) and
levels in maternal/cord blood than those seen in the
mercury will help to provide more spatial and temporal
Kitikmeot, Kivalliq and Inuvik regions. Mercury levels in
data on changes in dietary patterns or contaminant
the residents of one Nunavik community vary markedly
concentrations in food.
from year-to-year due to variation in availability of tradi-
tional/country food, but recent tissue levels are similar to Continued blood and hair monitoring and focussed
the levels foundin the late 1970s. While there is a longer dietary surveys in possible high exposure communities
history of Arcticenvironmental monitoring of mercury will guide northerners in their decisions on what, if any,
compared to other contaminants (e.g., organochlo- dietary modifications are warranted.
rines), differences in sampling strategies have made any
conclusions on trends very tenuous. Regular monitoring Toxicology
of tissue levels among communities with a range of
In certain Arctic populations, toxaphene residues are
exposures for mercury and selenium is advisable.
within the same range as the experimental studies where
Research on lead isotope signatures has shown that the effects on immune function and infant size have been
slightly elevated blood lead levels among some of the observed. While more information is needed on the
Inuit groups and the Dene and Métis are likely due to carcinogenic and endocrine-disruptive capacity of
the use of lead shot in hunting traditional/country foods, toxaphene, new and forthcoming information will be
and, therefore, its presence in wild game that is consumed. useful in a re-assessment of the toxicity and provisional
Blood cadmium levels are roughly 1.5 to 5 times higher tolerable daily intake (pTDI) of this chemical.
among Inuit than in Dene and Métis, Caucasians, and
The pattern of chlordane-related residue accumulation
Other. This difference is likely due to the high rate of
in humans parallels that seen in the highest levels of the
smoking among Inuit mothers and the high cadmium
Arctic marine food chain. Estimated chlordane intake
content in Canadian tobacco.
values for Arctic residents vary from levels less than the
Radiocesium entered the atmosphere as a result of Health Canada pTDI to levels approaching or exceeding
atmospheric testing of nuclear weapons. Since the first the higher US EPA TDI, depending on marine mammal
CACAR (1997), measurements of radiocesium levels in fat consumption. Based on the latest rodent studies at
Canadian caribou herds have shown that levels can now Health Canada, a thorough risk assessment with the goal
be considered insignificant. The radionuclides lead-210 of re-assessing the TDI should take into account that the
and polonium-210 are naturally occurring and supply major chlordane metabolite oxychlordane is almost 10-fold
most of the radiation dose to consumers of traditional/ more toxic than the parent chlordanes and nonachlors,
country food. These radionuclides accumulate in the
ii
and that trans-nonachlor and oxychlordane are among demonstrated despite the beneficial effects of omega-3
the more bioaccumulative chlordane contaminants. fatty acids from the traditional/country diet.
Contaminant and dietary nutrient Risk and benefit characterization,
interactions assessment and advice
There is some evidence that dietary nutrients such as
Contaminant exposure risks
polyunsaturated fatty acids, fish protein, and selenium
may interact with methylmercury toxicity at least on The primary contaminants of concern in the context of
the mechanistic level. The two former nutrients may be traditional/country food consumption in Arctic Canada
protective against methylmercury (MeHg) neurotoxicity; are the persistent organic pollutants (POPs), PCBs,
however, there is no conclusive evidence of such an chlordane and toxaphene, the toxic metal mercury and
effect. It is clear that there is a need for more studies naturally occurring radionuclides. The highest exposures to
designed specifically to address the role of nutrition in POPs and mercury are found in Inuit communities. In
the metabolism and detoxification of methylmercury. recent dietary surveys among five Inuit regions (Baffin,
Inuvialuit, Kitikmeot, Kivalliq and Labrador), mean
Epidemiology intakes by 20–40-year-old adults in Baffin, Kivalliq and
Inuvialuit communities exceeded the pTDIs for chlor-
Neurobehavioural effects of perinatal exposure to envi-
dane and toxaphene. High consumers (95thpercentile)
ronmental contaminants are best studied in prospective
of traditional/country foods are exceeding the pTDIs by
longitudinal cohort studies starting during pregnancy
many-fold for toxaphene, chlordane, and PCBs.The Inuit
because there are numerous other determinants of infant
populations that had the greatest exceedance of the
and child development that need to be documented and
pTDIs also had the greatest exceedance of the PCB
are best assessed during pregnancy or at birth. Examples
maternal blood guideline.
of these determinants are prenatal exposure to alcohol,
drugs and tobacco; exposure to other environmental Mercury is the toxic metal of greatest concern in the
contaminants such as lead; and intake of nutrients such Canadian Arctic. Dietary intakes of mercury were similar in
as selenium and omega-3 polyunsaturated fatty acids the two surveys conducted in 1987–1988 and 1998–1999,
(PUFA) during pregnancy. The ongoing Nunavik indicating there has been little change in dietary pattern
cohort study should help shed more light on contaminant and/or mercury concentrations in traditional/country
exposure and potential related health effects in the areas foods. Based on the exceedances of the provisional tolerable
of neurodevelopment and immune function. With the daily intake (pTDI) and of various blood guidelines,
establishment of this prospective Arctic birth-cohort, mercury, and to a lesser extent lead (from use of lead shot
there will be opportunities to look at other contaminants in hunting of game), may be a significant concern among
which may have neurodevelopmental effects, as well as Arctic peoples.
to study long-term effects that can only be documented
There is mounting evidence that a threshold may exist
at school age or later in the course of development.
for radiation-induced cancer and this threshold may be
Past research in Nunavik indicated that otitis media equal to or greater than 100 mSv. This issue is of signifi-
(middle ear infection) during the first year of life was cance to northerners, who were exposed in the past to
associated with prenatal exposure to p,p(cid:1)-DDE, HCB nuclear weapons fallout, or who have slightly higher
and dieldrin. Furthermore, the relative risk of recurrent exposures due to caribou meat consumption.
otitis mediaincreased with prenatal exposure to these
compounds. To date, the ongoing Nunavik study supports Nutritional benefits of traditional/country
the hypothesis that the high incidence of infections food diet
observed in Inuit children (mostly respiratory infections)
The nutritional benefits of traditional/country food and
may be due in part to high prenatal exposure to persistent
its contribution to the total diet are substantial, even
organic pollutants (POPs).
though only 6–40% of total dietary energy may be from
Preliminary data from the Nunavik cohort indicate that this food source. Research findings are consistent across the
the strength of the negative association of polychlorinated Canadian Arctic and confirm that decreasing traditional/
biphenyls (PCBs) on birth weight for newborns in country food in the diet is likely to have negative health
northern Québec was comparable to the associations consequences, in part through the corresponding increase
with prenatal exposure to alcohol and smoking during in total fat, saturated fat and sucrose intakes above the
pregnancy. The negative effects of prenatal PCB exposure recommended levels. Traditional/country food also
on birth weight and duration of pregnancy could still be contributes significantly more protein, iron and zinc to
iii
the diets of Inuit children than imported foods. The Benefit and risk communication
increase in diabetes, cardiovascular disease and obesity
Effective communication is fundamental to the aims of
have been linked to this shift away from the traditional/
the NCP. Communication efforts incorporate Aboriginal
country food diet. The substantial nutritional benefits of
knowledge on the nutritional benefits and risks associated
traditional/country food and its contribution to the total
with the consumption of traditional/country foods and
diet have been documented; however, further research is
of imported foods, and on the importance of a traditional
needed on the negative health consequences of not con-
lifestyle to overall health and well-being. These efforts
suming traditional/country food.
provide northerners with the appropriate information
to make more informed decisions about harvesting and
Benefit and risk management and
consumption of both traditional/country food and
assessment framework imported foods, and also to avoid some of the mistakes
of earlier communication efforts related to environmen-
Benefit and risk assessment and management relating
tal contaminants. No one method of communication is
to contaminants in traditional/country food involves a
best, but what is needed is a variety of methods and
consideration of the type and amount of food consumed
materialsappropriate to communities in different regions
and the sociocultural, nutritional, economic, and spiritual
and specific to groups within each community, all aimed at
benefits associated with traditional/country foods.
providing opportunities for two-way exchanges of informa-
Benefit and risk management decisions must involve the
tion and allowing an understanding of the issue to develop.
community and must take all aspects into account to
The practice of risk communication has changed over
arrive at a decision that will be the most protective and
the past two decades, building upon lessons learned
least detrimental to the communities. Regardless of the
along the way. In place of one-way models of information
decision taken, some health risks associated with exposure
distribution, NCP-II strove toward shared decision making
to contaminants may remain. In the Arctic, these risks
through partnerships involving territorial Health
are outweighed by the benefits of continued consumption
Departments and regional contaminants/health commit-
of traditional/country foods. The uncertainty over risks
tees, community representatives and representatives of
and benefits will continue to pose a large and complex
Aboriginal organizations at all stages of the risk manage-
public, moral and political dilemma.
ment and risk communication process.
ITK/Eric Loring
iv