Assessment of Dietary Exposure to Trace Metalsin Baffin Inuit FoodHing Man Chan, Christine Kim, Kishan Khoday, Olivier Receveur, andHarriet V. KuhnleinCentre for Nutrition and the Environment of Indigenous Peoples, McGill University,Montreal H9X 3V9 Canada

Chronic metal toxicity is a concern in theCanadian Arctic because of the findings ofhigh metal levels in wildlife animals and thefact that traditional fd statutes a majorcomponent of the diet of indigenous peo-pIes. We ned exposure totrce metalsthough traditional fod resources for Inuitliving in the community of Qikiqtajuaq onBaffin Island in the eastern Arctic. Mercury,cadmium, and lead were d ined i localfood resources as normally prepared andeaten. Elevated concentrations of mercury(>50 pg/1lO g) were found in ringed sealliver, narwbal matnak beluga meat, and bel-uga mattak, and actively hig on a-tions of cadmium an lead (>.100.pg/100 g)were fiond in ringed seal liver, mussels, andkelp. Quantified dietary recalls taken season-ally reflected normal consumption patternsof these food resources by adu't men andwomen (>20 years old) and children (3-12years old). Based on traditional food con-sumpt~ion, the average daily intake levels oftotal mercury for both adults (65 pg forwomen and 97 pg for men) and children (38pg) were higher than the anadian averavalue (16 pa). The average weeldy intake ofmercury for all age groups exceeded theintae guides (5.0 pg/cg/day). establishedby the Joint Food and AgricultureOrganization/World Health OrganizationExpert Committee on Food Additives andContaminants. The primary fiods that con-tributed to metal intake for the Banu Inuitwere: tinged seal meat caribou me, andkelp. We review the superior nutritionalbenefits and potential health risks of tmdi-tional food items and implications for moni-toring metal contents of food, cinical symp-toms, and food use. Key ary cadium,Canada, diet, exposure assessment, Inuits,lead, mercury. Environs Health Perspect103:740-746 (1995)

Trace metals occur naturally in the earth'scrust and can neither be created nordestroyed by humans. However, humanactivities such as mining, industrial use,sewage disposal, and hydro-projects havegreatly increased the mobilization andbioavailability of metals and increased thechance of exposure to harmful concentra-tions (1). Natural baseline levels of tracemetals in air, soil, rivers, lakes, and oceansare usually low, but in certain forms and atsufficiently high concentrations, trace metalscan be toxic to living organisms. The majorsource of human exposure to trace metalsfrom the environment is from food (2).

The Canadian north is richly endowedwith metal deposits. Natural withering of

ore and mining activities are major sourcesof trace metal contamination in theCanadian Arctic (3). There is some evi-dence for deposition of aerosol lead (4),suggesting long-range transport may also bea possible source of lead contamination. In1986, 14 mines were producing lead, zinc,silver, gold, copper, cadmium, and arsenicin the Canadian Arctic; before 1986, 68mines had been developed and abandoned(5). Mining sites can be local point sourcesof metal contamination because elevatedlevels of metals are present in sludge, tail-ings, waste rock, dusts, and gaseous emis-sions from smelting and refining.Moreover, withering and leaching of tracemetals in abandoned mine tailings mayhave a long-term impact on the environ-ment. Severe metal pollution is found inrivers and lakes near abandoned miningsites in the Northwest Territories (6). Forexample, tailings from the Discovery goldmine, which operated between 1950 and1969, were contaminated with mercury,which affected fish in adjacent lakes. Thelevels of lead, zinc, nickel, arsenic, and mer-cury are still high (7). The Nanisivik mineon Baffin Island is one of the two operatinglead-zinc mines in the Canadian Arctic.Concentrations of lead, zinc, cadmium,and arsenic in ocean sediments near theNanisivik mine are higher than predevelop-ment levels (8), and relatively high metalconcentrations have been reported in biotaof various trophic levels in StrathconaSound near Nanisivik (9). The long-termeffects of the elevated metal levels on theecosystem, including wildlife foodresources, is still unknown.

In the Canadian Arctic, cadmium, lead,and mercury contamination is of majorconcern (10), partly because of bioaccumu-lation in the food chain. Elevated levels ofthese metals have been reported in terrestri-al, fresh-water, and marine biota (5,11,12).For example, high concentrations of cadmi-um were found in kidney of narwhal (6360pg/100 g) (13) and of caribou (16,600pg/100 g) (14). Although concentrations ofmetals in the biota are generally lower inthe Arctic than in southern Canada, there isconsiderable concern for their possibleadverse effects on human health, particular-ly for indigenous peoples living in remoteareas dependent on wild animals and plantsfor food. Because of the nutritional benefitsand cultural significance of these traditionalfood items (15-26), their consumption is

encouraged by native leaders, health profes-sionals, and government agencies. It wasestimated that the average annual per capi-ta consumption of traditional food amongInuits is more than twice the estimatedCanadian average annual consumption ofmeat and fish (27). Preliminary estimationsof metal intake from diet based on harvestdata and metal contents in wildlife samplessuggest that some indigenous peoples mayhave undesirable levels of metal exposurefrom their traditional diet (14,28,29).Therefore, more detailed and reliable stud-ies on dietary intake are required to assessthe health risks of trace metals on indige-nous peoples. The best way to assess riskfrom multiple contaminants is a compre-hensive dietary survey and chemical analy-sis of contaminant contents in the food col-lected from the community (30).

In this paper we report the levels ofcadmium, lead, and mercury in traditionalfood items collected from Qikiqtarjuaq(Broughton Island) on eastern BaffinIsland, Northwest Territories (Fig. 1). Thelevels of dietary exposure from traditionalfood to cadmium, lead, and mercury forinhabitants in Qikiqtarjuaq were estimat-ed. The related health risks and benefits oftraditional foods are discussed.

MethodsCommunity Dietary Survey andFood Sampling

We conducted 24-hr recall interviews asdescribed in Kinloch et al. (15). Briefly,interviews were conducted in 6 bimonthlyseasons representing the entire year inQikiqtarjuaq (population 586), a commu-nity selected to represent the Baffin Inuit,during 1987-1988. All members of thecommunity were asked to participate, andnonparticipation bias was controlled. In

Address correspondence to H.M. Chan, Centre forNutrition and the Environment of IndigenousPeoples, Macdonald Campus, McGill University,21,111 Lakeshore Road, Ste. Anne de Bellevue,Quebec H9X 3V9 Canada.We acknowledge the many individuals who havecontributed to this work. In particular we thankthe leadership, the Hamlet Council members,community members, and the many interviewerswho participated. Special thanks to Billy Arnaqaq,Daisy Arnaqaq, and Ooleepeeka Audlakiak. Forlaboratory and computer assistance we thankAghdas Zamani, Rula Soueida, Doug Reed, andLori Bell. Funding for the initial community workwas provided through Health Canada (HWC-MSBHQ88-8901650 and HWC-NT-87-88-014-CO) and the National Health Research andDevelopment Program (6605-3430-T). This pro-ject was supported by the Arctic EnvironmentalStrategy, Department of Indian Affairs andNorthern Development, and the Natural Sciencesand Engineering Research Council of Canada.Received 21 December 1994; accepted 12 April1995.

Environmental Health Perspectives740

...... -1-i; .S~is is i~iJ BiI .

Figure 1. Map of Qikiqtarjuaq, Baffin Island, Northwest Territories, Canada.

all, 90 adult females (nonpregnant/nonlac-tating), 89 adult males, and 104 children(age 3-12) were interviewed during theyear for a total of 1153 recalls (401, 301,and 451, respectively). Not all subjectsrecalled eating traditional food. The subsetof 734 subjects (291 female, 229 male, and214 children) who recalled eating tradi-tional food items were used for evaluationof metal intake.

Food samples were collected and pre-pared by Inuit project assistants in theforms in which the foods were normallyconsumed (21) during the interviewingperiods. At least three subsamples weretaken from different areas of the organsand combined as one sample. Raw andprepared food samples may not be fromthe same animals.

We calculated daily metal intake levelsby multiplying the amount of food itemconsumed during the day of interview bythe average metal concentration of thefood item. The respective contributions totrace metal exposure were then summedover all traditional food consumed for eachfood recall.

During the course of the research, thecommunity was encouraged to participateby keeping the Hamlet Council informedof progress and by regular radio messages.

Results were returned to the BaffinRegional Inuit Association and to theHamlet Council of Qikiqtarjuaq. A reportwas written for the community and trans-lated into Inuktitut.

Analysis of Food SamplesNitric acid (ultrapure grade) was obtainedfrom J.T. Baker (Baxter, Missassagua,Ontario). Metal standards were prepareddaily by diluting commercial standardsolutions (1000 ppm; ACP chemicals, St.Leonard, Quebec) with 40% nitric acid(same acid concentrations as samples). Allglassware used was acid washed with 20%hydrochloric acid overnight.

Food samples were sampled, portioned,and stored at -200C until analyzed for cad-mium, lead, and mercury. For analysis, thesamples were thawed and two aliquots ofapproximately 1.0 g of each sample wereweighed and dried to constant weight (in avacuum oven at 600C and at a pressure ofapproximately 30 Pa for 24 hr). Driedsamples were weighed and digested with 2mL nitric acid at room temperatureovernight. The samples were then heatedto 600C for 2 hr. After the digests werecooled to room temperature, 2 mL nitricacid were added and they were heated to600C for 2 hr to complete the digestion.

The digested samples were made up to10 mL with deionized water, and the metalcontents were analyzed using a Hitachi Z-8200 atomic absorption spectrophotome-ter with Zeeman background correctionand a SSC-1 10 autosampler. Metal con-tents were measured by flameless modewith a platform graphite furnace withexternal reference standards. Palladium (50ppm) was used as modifier for lead analy-sis. Total mercury was measured by coldvapor generation with a Hitachi HFS-2continuous flow injection hydride forma-tion system. The detection limits (threetimes the standard deviation of the blanks)are 0.5 ppb (0.05 lig/100 g tissue) for cad-mium, 5 ppb (0.5 pg/100 g tissue) forlead, and 0.2 ppb (0.02 pg/100 g) for mer-cury. Food sample concentrations belowthe detection limits were regarded as zero.

Two sample blanks were analyzedtogether with each batch of samples.Concentrations of the three metals inblanks were below the detection limits inall analysis. A spiked blank was analyzedduring each analysis to ensure day-to-dayreproducibility. Each standard and samplewas measured in duplicate, and the samplewas reanalyzed if the relative standard devi-ation of the two measurements was higherthan 5%. Coefficients of variations of thethree replicates of the samples were gener-ally less than 10%, and the mean was usedas the representative value for the sample.Standard reference materials from theNational Institute of Standards andTechnology (oyster tissue SRM 1566a,apple leaves SRM 1515, and bovine liverSRM 1577b) were digested and analyzedwith each batch of samples. Results of themetal concentrations always fell within 1SD of the certified values. Our laboratoryalso participated in interlaboratory com-parison exercise organized by the ArcticEnvironmental Strategy of the Departmentof Indian Affairs and NorthernDevelopment of Canada.We tested differences in contaminant

intakes across age groups by ANOVA fol-lowed by Bonferroni t-tests. Differences infood intake according to exposure cate-gories were tested by Student's t-tests.Because food and contaminant intake dis-tributions are positively skewed in thesedata sets, all data were transformed [log(value + 1)] before performing statisticaltests (SAS/STAT, version 6, SAS InstituteInc., Cary, North Carolina). A p-value of<0.05 was considered significant in all sta-tistical tests.

ResultsCadmium, mercury, and lead were detectedin 87 out of90 food samples measured; theirconcentrations are presented in Table 1. The"action levels" established by Agriculture

Volume 103, Number 7-8, July-August 1995 741

Table 1. Trace metal concentrations in Inuit food (pg/100 g wet weight)

Food source na Mercury Cadmium Lead Food source na Mercury Cadmium LeadRinged seal (Phoca hispida)Meat, raw 2 30.9 (11.4,50.3)bMeat, boiled 2 26.7 (18.7,34.7)Meat, aged 1 16.9Blubber, raw 1 9.9Blubber, aged 2 11.9 (10.7,16.4)Blubber, boiled 1 10.0Broth 1 8.3Liver, raw 3 429.3 (471.5)Heart, raw 2 15.8 (7.8,23.9)Brain, raw 1 7.9Ringed seal pupMeat, raw 1 18.2Meat, boiled 1 45.5Bearded seal (Erignathus barbals)Meat, raw 2 17.2 (16.7,17.9)Meat, boiled 2 28.0 (25.6,30.4)Broth 1 3.5Intestine, raw 1 21.6Intestine, boiled 1 33.4Narwhal (Monodon monoceros)Meat, dried 2 90.1 (7.5,172.7)Blubber, raw 1 13.0Blubber, aged 1 12.3Blubber, boiled 2 11.1 (10.4,11.7)Mattak, raw 1 55.9Mattak, aged 1 195.0Mattak, boiled 2 73.5 (59.7,87.3)Flippers, aged 1 10.8Beluga (Delphinapterus lecas)Meat, dried 1 796.9Mattak, raw 1 103.5Blubber, raw 1 12.8Walrus (Odobenusrosmarus)Meat, raw 2 16.9 (12.4,21.5)Meat, aged 2 12.1 (11.3,12.9)Meat, boiled 2 25.2 (11.6,38.7)Blubber, raw 2 6.4 (10.1,2.8)Blubber, aged 2 6.6 (4.4,8.8)Blubber, boiled 1 11.6Mattak, raw 2 2.7 (1.4,4.0)Mattak, aged 1 5.8

Action level 50

44.2 (34.5,53.8)66.2 (32.5,99.9)42.911.63.7 (4.3,3.1)2.04.2

213.6 (147.8)23.7 (20.2,27.5)11.5

1.21.0

13.7 (6.4,21.0)28.0 (24.5,31.5)8.3

98.796.5

60.9 (85.1,36.7)5.28.18.1 (8.8,7.4)5.82.82.4 (1.1,3.7)

30.5

41.71.24.0

15.6 (12.8,18.5)21.7 (20.5,22.8)26.0 (22.8,29.2)2.1 (1.8,2.3)6.9 (1.9,11.8)1.43.8 (2.7,4.8)4.4

100

6.7 (4.4,9.0)9.4 (6.9,11.9)

18.110.612.8 (15.4,10.2)8.94.43.3 (1.6)6.9 (6.5,7.3)

861.9

6.110.0

6.9 (5.9,7.9)6.0 (5.6,6.4)

10.55.5

10.0

33.6 (12.6,54.6)26.7

111.7149.8(149,150)

7.68.99.6 (9.3,9.9)

125.0

4.53.2

97.3

24.8 (22.0,27.6)15.5 (8.4,22.6)29.1 (27.6,30.6)25.8 (12.3,39.3)35.9 (11.4,60.4)7.1

20.4 (4.0,36.8)75.4

Polar bear (Ursus maritimus)Meat, raw 2Meat, boiled 2Fat, raw 2Fat, boiled 2Caribou (Rangifertarandus)Meat, raw 2Meat, dried 1Meat, boiled 2Fat, raw 2Brain, raw 1Brain, boiled 1Tongue, raw 1Stomach, raw 1Stomach contents 1Heart, raw 1Lungs, raw 1Arctic char (Salvelinus naresi)

22.3 (17.7,26.9) 17.9 (12.2,23.5)45.7 (26.8,64.5) 19.3 (5.5,33)7.2 (6.0,8.5) 3.6 (2.7,12.4)8.4 (6.6,10.8) 7.6 (2.7,12.4)

10.2 (3.8,16.6) 5.5 (5.6,5.4)3.8 1.75.7(4.5,6.8) 3.5(2.9,4.1)5.8 (2.6,9.0) 5.3 (0.2,10.4)0 0

10.3 09.6 0.1

12.5 26.16.1 04.1 0.39.8 3.7

Meat, raw 2 3.5 (0,7.0)Meat, boiled 2 17.9 (7.5,28.4)Meat, dried 2 23.6 (11.6,35.7)Skin, raw 1 9.5Skin, boiled 1 4.3Sculpin (Acanthocottus sp.)Meat, bone, inside 1 22.0Mussels (Mytilus edulis)Contents, raw 1 8.2Contents, boiled 1 17.3Kelp (Laminaria sp.)Raw 1 10.6Blackberries (Empetrum nigrum)Raw 1 2.9GreensOongooli, raw 1 4.5Okowyot, raw 1 4.3

6.7 (2.7,10.7)5.6 (4.2,7.0)

19.5 (17.2,21.8)2.95.8

2.3

101.9111.3

173.0

0

6.231.3

200

aNumber of independently harvested samples, except where noted.bMean (sample values).

Canada to monitor the potential contamina-tion of the three metals are also presented forcomparison. Agriculture Canada may initi-ate on-farm inspections and feed analysis to

assess potential problems for animals andhuman health when action levels are exceed-ed (31). If sufficient magnitude of a residuelevel is established, the Agri-Food SafetyDivision of Agriculture Canada will recom-

mend to Health and Welfare Canada thatthe food not be used for human or pet foodproducts. The mean, median, and range ofmercury in all food samples were 37.9, 11.5,and 0-796.9 pg/100 g, respectively.Concentrations of mercury in ringed sealliver, narwhal mattak, beluga meat, andbeluga mattak were higher than the actionlevel of 50 pig/100 g or 0.5 ppm set byAgriculture Canada. The mean, median, andrange of cadmium in all food samples were

22.4, 6.0, and 0-213.6 pg/100 g, respective-

ly. The corresponding figures for food com-

posites found in Canada are 1.37, 0.54, and0.007-29.7, respectively (32). Concentra-tions of cadmium in ringed seal liver, mus-

sels, and kelp were higher than the actionlevel of 100 pig/100 g or 1.0 ppm. Themean, median, and range of lead were 41.2,18.6, and 3.2-861.9 pg/100 g, respectively.The corresponding figures for food compos-

ites found in Canada are 2.99, 1.47, and0.142-40.7, respectively (32). Concentra-tions of lead in ringed seal liver, mussels, andkelp were higher than the action level of 100pg/100 g or 1.0 ppm.

In Table 2, food items are classified intofive major categories, and their metal con-

centrations are compared to the values ofCanadian food composites. Like Canadianfood, higher concentrations of all threemetals measured were found in organ meats

of traditional food. Moreover, cadmium

and lead levels in shellfish and mercury lev-els in meat were also high. Although aver-

age levels of the three metals in the tradi-tional food items measured in this studywere generally higher than those ofCanadian market food, the ranges of levelsof lead in meats and vegetables, cadmiumin organ meats, and mercury in fish were

similar. Because of the relatively small sam-

ple size in each food category, the average

levels can be strongly influenced by certainfood items. For example, the mean cadmi-um level in vegetables was much higherthan the Canadian value because of thehigh cadmium concentrations found inkelp. Similarly, the high level of mercury inmeat was a result of the high concentrationsfound in the meat of marine mammals.

The seasonal average daily metalintakes during days of traditional foodconsumption for both men and women

Environmental Health Perspectives

22.6 (16.8,28.4)45.9 (15.2,16.6)54.3 (49.3,59.3)39.9 (15.7,64.1)

3.4 (1.6,5.2)68.478.3 (67.5,89.1)35.0 (13.5,56.5)5.7

37.03.8

41.422.419.19.7

54.3 (49.0,59.6)20.1 (7.1,33.1)14.5 (9.5,19.5)57.67.5

43.4

54.4100.1

50.7

11.1

26.229.2

742

MMEI

in Table 3. The data are not normally dis-tributed. A log transformation was per-

formed; the geometric means and 95%confidence levels are presented. Data forchildren 3-12 years of age are also shown.The intake values were compared to the

Table 2. Trace metal levels in food categories (pg/100 g)Food n Mercury Cadmium LeadMeat This study 17 Mean 52 24 23

Median 22 19 16Range 4-797 1-66 3-78

Canadaa 18 Mean 0.9 5Median 0.4 2Range 0.1-7 0.3-27

Organ meats This study 27 Mean 51 53 86Median 12 4 11

Canaab1 Range 4-429 3-2140 3-862Canadab 12 Mean 4 271 9

Median 2 17 9Range 1-1880 1-18500 4-297

Fish This study 4 Mean 17 9 33Median 18 7 33Range 4-24 2-20 14-54

Canadaa 5 Mean 11 5Median 0.5 2Range 0.1-8 0.7-17

Shellfish This study 2 Mean 8 107 77Median 8 107 77Range 7-8 101-111 54-100

Canadaa 1 Mean 30 30MedianRange

Vegetables This study 4 Mean 6 53 29Median 5 31 29Range 3-10 0-173 11-51

Canadaa 37 Mean 2 49Median 1 5Range 0.2-12 0.3-254

aCalculated from data in WHO document (33); data for mercury not available.bCalculated from data in Dabeka and McKenzie (32).

Table 3. Trace metal daily intake (pg/day) on days with traditional food for Inuit in QikiqtarjuaqGroup Mercury Cadmium LeadWomen >20 years (N= 291) Arithmetica 122 ± 155 144 ± 204 67 ± 93

Geometric 65 (56-75) 56(47-67) 43(38-48)Median 76 56 44

Men >20 years (N= 229) Arithmetic 166 ± 177 169 ±235 85 ± 104Geometric 97 (84-114) 76(63-91) 54(47-61)Median 110 73 54

Children 3-12 years (N= 214) Arithmetic 66 ± 75 89 ± 159 35 ± 51Geometric 38 (33-44) 34(28-42) 23(20-26)Median 39 31 21

Canadab 16 69 125

"Values are arithmetic means ± SD and geometric means with 95% confidence intervals in parentheses.bFrom Conacher and Mes (30).

Table 4. Comparison of calculated weekly intake to the provisional tolerable weekly intake (PTWI) (pg/kgbody weight/week)8Group Mercury Cadmium LeadWomen >20 years (N = 401) 6.6 5.8 4.4Men >20 years (N= 301) 8.0 6.2 4.4Children 3-12 years (N= 451) 6.3 5.7 4.6PTWIb 5.0 7.0 25.0

Geometric mean of daily intake x 7 x probability of consuming traditional food on any given day/bodyweight (50 kg for women, 65 kg for men, and 20 kg for children). The probability of consuming traditionalfood was calculated as the proportion of all food recalls containing traditional food (291/401, 229/301,and 214/451 for women, men, and children, respectively).bFrom WHO (33).

Canadian average intake levels (30). Thedaily mercury intake levels from traditionalfood for both adults and children were

higher than the Canadian average.

Cadmium levels were similar and lead lev-els were lower than the Canadian average.

Assuming the average body weights ofwomen, men, and children are 50, 65, and20 kg, respectively, and that the probabilityof consuming traditional food on any givenday is 0.73, 0.76, and 0.48 for adultfemales, males, and children, respectively(based on the proportion of food recallswith traditional food mentioned), the aver-

age weekly intake was calculated (geometricmean of daily intake x probability of con-

suming traditional food x 7/body weight)and compared to the provisional tolerableweekly intake (PTWI) levels established bythe Joint Food and AgricultureOrganization/World Health OrganizationExpert Committee on Food Additives andContaminants (33) (Table 4). The weeklymercury intake levels for all age groups

exceeded the safe intake guidelines.The most consumed traditional foods

in Qikiqtarjuaq expressed as percentages ofthe total weight of traditional food men-

tioned in the food recalls and their contri-bution to metal exposure as percentages oftotal intake of each metal are presented inTables 5-7. For all individuals studied,ringed seal (Phoca hispida) meat was themost frequently consumed item. It consti-tuted about one-third by weight of all tra-ditional food eaten by both adults andchildren. It was also the major contributorto all three metals studied: about 40% formercury, 70% for cadmium, and 20% forlead. Little bearded seal (Erignathus barba-tus) was consumed in comparison to ringedseal. Ringed seal meat and liver and nar-

whal (Monodon monoceros) mattak togethercontributed about 75%, 71%, and 70% ofmercury in women, men, and children,respectively. Ringed seal meat was the sin-gle major contributing food item for cad-mium in the diet; caribou (Rangifer taran-dus) meat and kelp (Rhodymenia or

Laminaria spp.) also contributed to

approximately 10% of cadmium in thediets of both adults and children. For lead,the major contributing food items were

ringed seal meat, caribou meat, and Arcticchar (Salvelinus alpinus) meat. Together,these items accounted for about 50% oflead in the adult diets and over 60% oflead in the diets of children.

DiscussionThe high concentrations of cadmium, lead,and mercury found in some of the fooditems (e.g., exceeding the action level set

by Agriculture Canada) (31) deserve con-

cern. Because of limited resources, onlyone or two samples of each food item were

Volume 103, Number 7-8, July-August 1995

across three age groups (20-40, 41-60,and >60 years) were compared, and no sig-nificant differences were found (data notshown). Therefore, the results from allthree age groups were pooled, and theresults of average daily intake are presented

743

Table 5. Proportionate distribution of metals intake from traditional food most consumed by Baffin Inuitwomen >20 years old in Gikiqtarjuaq8

Contribution (%) to total intakeFood Traditional food Mercury Cadmium Lead

Ringed seal meat 31.6 40.7 71.9 23.5Caribou meat 24.1 7.2 3.4 10.0Narwhal mattak 8.9 21.5 1.7 5.4Ringed seal broth 6.0 2.2 0.9 2.2Artic char meat 5.8 2.7 1.4 18.4Walrus meat 4.2 2.3 3.1 5.6Ringed seal blubber 3.0 1.4 0.7 2.5Blackberries 2.5 0.3 0.0 1.9Bearded seal meat 2.4 1.8 1.3 1.1Ringed seal pup meat 2.2 0.8 0.0 0.5Walrus blubber 1.4 0.4 0.4 4.3Kelp 1.3 0.4 5.8 3.8Narwhal meat 1.1 3.1 1.8 2.2Caribou fat 0.8 0.2 0.1 2.1Ringed seal liver 0.6 11.9 5.0 0.2Narwhal blubber 0.5 0.3 0.1 1.7Total 96.4 97.2 98.0 85.4

aData from a total of 291 food recalls containing traditional food are pooled and the relative contributionof each food item is expressed as the percentage of the total intake. Traditional food is by weight.

Table 6. Proportionate distribution of metals intake from traditional food most consumed by Baffin Inuitmen >20 years old in Qikiqtarjuaqa

Contribution (%) to total intakeFoodRinged seal meatCaribou meatNarwhal mattakArtic char meatRinged seal brothRinged seal blubberRinged seal pup meatBearded seal meatWalrus meatBlackberriesNarwhal blubberMusselsWalrus blubberPolar bear meatCaribou fatKelpTotal

Traditional food27.623.511.17.74.83.33.02.52.51.51.00.70.70.60.40.4

91.3

Mercury33.68.6

27.24.41.71.44.92.62.00.20.50.20.21.30.10.2

89.1

Cadmium72.95.02.92.30.90.90.12.62.60.00.33.20.20.60.13.5

98.1

Lead22.011.08.0

22.92.02.92.51.55.21.64.73.50.32.71.52.1

94.4

aData from a total of 229 food recalls containing traditional food are pooled and the relative contributionof each food item is expressed as the percentage of the total intake. Traditional food is by weight.

Table 7. Proportionate distribution of metals intake from traditional food most consumed by Baffin Inuitchildren 3-12 years old in Qikiqtarjuaq8

Contribution (%) to total intake

Food Traditional food Mercury Cadmium Lead

Ringed seal meat 34.6 46.6 75.3 28.8Caribou meat 22.4 8.1 3.4 12.9Narwhal mattak 8.2 23.1 1.6 6.1Arctic char meat 8.2 6.1 1.8 20.5Blackberries 7.8 1.1 0.0 8.2Ringed seal broth 6.4 2.6 1.0 2.7Ringed seal blubber 2.1 1.0 0.5 1.9Kelp 1.6 0.8 10.0 7.8Blueberries 1.2 0.0 0.0 0.0Narwhal meat 0.8 3.7 1.9 2.7Total 93.3 93.1 95.5 91.6

"Data from a total of 214 food recalls containing traditional food are pooled and the relative contributionof each food item is expressed as the percentage of the total intake. Traditional food is by weight.

collected and measured in this study. Forthose food items with more than one sam-ple, relatively high values of relative stan-dard deviation (5-136%; Table 1) werefound, suggesting that there is a high levelof intravariation in metal concentrations infoods. Nevertheless, the concentrations ofcadmium, lead, and mercury found in theraw food samples in this study are compa-rable to those of wildlife reported in the lit-erature (9,11,13,29). For example, cadmi-um and total mercury in ringed seal meatcollected from the Baffin region werereported to range from 0.05 to 0.71 pg/gand 0.04 to 0.69 pg/g, respectively (com-pared to 0.44 pg/g and 0.31 pg/g found inthis study). It has to be emphasized thatthe samples of this study were collected byInuit in the community for food use, andprepared food samples were included inthis study. Therefore, they may better rep-resent the typical levels of metals in foodthan the samples collected by wildlife biol-ogists for environmental studies. However,because of the high coefficients of varia-tions of metal concentrations in food, thedietary intake estimations based on thesevalues should be interpreted with caution.

Metal levels in many types of tradition-al food were higher than in correspondingmarket food (Table 2). However, the dif-ference of components in the traditionalfood groups and those of the market foodmakes the direct comparison of the levelsof metals difficult. For example, marketmeats are all from domesticated land ani-mals (beef, pork, etc.), whereas meats oftraditional food in Baffin are mainlymarine mammals such as seal, narwhal,walrus, beluga, etc. It is known that cadmi-um and mercury can bioaccumulate in theCanadian Arctic food chain (11).Therefore, animals on higher trophic levelstend to accumulate higher metal levelsthan those of lower trophic level. Marinemammals are usually on the third or fourthtrophic level in the food chain (9,34),whereas cattle raised in Canadian farms aremainly on the first or second trophic level.Therefore, average concentrations of cad-mium and mercury in some traditionalfoods were higher in comparison to thelevels of comparable market foods (Table2). The reason for generally higher leadlevel in traditional food groups is notknown. However, there is a general trendthat the prepared food items have higherlead concentrations than the raw samples(Table 1). Contamination by cookingutensils may be a factor and should be fur-ther investigated.

There are some similarities betweenmetal levels found in traditional and mar-ket food. For example, high cadmium andmercury concentrations can be accumulat-ed in meat organs and shellfish (35,36)

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and cadmuim and mercury levels of thesetwo groups are similar to the values foundin market food. The fact that cadmiumconcentrations in green vegetables otherthan kelp (e.g., oongooli and okowyot)were low and comparable to the averagevalues of market food is a good sign, sinceconcentrations in leafy vegetables are gen-erally a good indicator of cadmium in thelocal soil (35). The high cadmium concen-tration in kelp could be due to fast growthrate of this species and probably a highabsorption rate of cadmium from seawater.It is important to determine typical cadmi-um concentrations in kelp because it con-stituted a significant percentage (10%) ofcadmium in the diet of children (Table 7).

Because of the difference of metal levelsin different food groups between marketand traditional food, the importance offood groups in terms of their contributionto the metal levels in the diet also differ. Ina market food diet, the major sources ofmetals are cereals and vegetables for cadmi-um; spices and herbs, canned food, andshellfish for lead; and fish for mercury(37). However, in the traditional diet inQikiqtarjuaq, the major sources of bothcadmium, mercury, and lead are frommeat and organ meats.

From the results of these studies, it wasfound that the estimated average levels ofmercury derived from the traditional foodin Qikiqtarjuaq exceeded the provisionalPTWI levels set by the Joint FAO/WHOExpert Committee on Food Additives(Table 4) (33). The PTWI has been adopt-ed by the WHO for unavoidable food pol-lutants such as trace metals. It is designedto level out the great variation betweendaily intakes and avoid the need to aban-don certain food items which have highlevels of pollutants but are not consumedfrequently, thereby protecting the con-sumer. These levels were set in the hopethat the situation would improve and thatit would be possible at a later time to setdaily maximum intake recommendations.Therefore, the safety considerations are notas conservative as for acceptable daily intakelevel. Our results indicate potential healtheffects due to mercury exposure. A dailyintake of 3-7 pg methylmercury/kg bodyweight may cause adverse effects on thenervous system, manifested as an approxi-mately 5% increase in the incidence ofparaesthesia (36). Assuming 80% of thetotal mercury is in the form of methylmer-cury (11), and average daily intake is equalto the average weekly intake (Table 4)divided by 7, the average daily intake ofmethylmercury will be 0.75 pg/kg bodyweight for women, 0.91 pg/kg body weightfor men, and 1.5 pg/g body weight for chil-dren. These values are higher than the no-adverse-effect level of 0.48 pg methylmer-

cury/g body weight. Moreover, the childrenalso have relatively higher intake of lead (23jig/day or 4.6 pg/kg/week) compared toadults. Therefore, potential effects on thecentral nervous system during developmentmay be of concern (38).

Tobacco is a major source of cadmium,and smoking is common among the inhab-itants of Qikiqtarjuaq. The averageCanadian cadmium intake level is high (69jig/day) (31), indicating there may be sub-stantial contribution of dietary cadmiumintake from Canadian market food.Although cadmium intake from traditionalfood was lower than the PTWI in thisstudy, studies of health status of the peoplein Qikiqtarjuaq related to cadmium intakewould be prudent.

Because ringed seal meat is such animportant component of the traditional dietand also a contributor to metal intake (70%for cadmium, 20% for lead, and 40% ofmercury), metal concentrations in this foodshould be monitored. The levels of mercuryin narwhal mattack, lead in Arctic charmeat, and lead and cadmium in kelp couldalso be included in monitoring programs. Ahigh lead concentration (862 jig/100 g) wasfound in ringed seal brain. Because sealbrain was not a regular component of thetraditional diet, it was not a major source oflead in the diet. Similarly, even though themercury concentrations in beluga meat (797jig/100 g) and cadmium concentrations inringed seal liver (214 pg/100 g) were high,they do not contribute significantly to thetotal dietary exposure of mercury and cad-mium reported here.

It has to be emphasized that the objec-tive of this study was to identify potentialhealth risk from metal exposure at a com-munity level. The arithmetic means ofdaily metal level were much higher thanthe geometric means and the medians(Table 3). The skewed distribution suggeststhat high intake levels are results of someinterviewees consuming food items withhigh cadmium concentrations (e.g. caribouliver or kidney) on the interviewing days.For example, the maximum intakes were1833 jig Cd/day for women and 2051 jigCd/day for men. These results suggest thatsome individuals may have much higheraverage weekly metal intake than the aver-age level presented in this study.Monitoring programs to further assess thebody burden and potential health risks,including the use of various biologicalmarkers such as urine (cadmium), blood(lead), and hair (mercury) could be consid-ered. Any recommendations on traditionalfood consumption should take intoaccount the importance of cultural, social,and nutritional values of traditional food,as discussed elsewhere (39l).

It is also important to note that both

diet and contaminant levels vary amongcommunities (40). Metal intake levels pre-sented in this study may or may not neces-sarily reflect food use and metal exposurein other communities in the region.Further research is needed to clarify thisimportant issue.

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8. Arctic Laboratories Ltd. Cadmium, lead, andzinc particulate fluxes and seawater concentra-tions, Strathcona Sound, NWT: winter-springstudies, 1984-5. Yellowknife, NorthwestTerritories:Indian and Northern AffairsCanada, Nothern Affairs Program, 1986.

9. Wagemann R. Comparison of trace metals intwo groups of ringed seal (Phoca hispida) fromthe canadian Arctic. Can J Fish Aquat Sci46:1558-1565 (1989).

10. Eaton RDP, Fuller WA. Metallic contaminantsof significance to Northwest Territories resi-dents. Yellowknife, Northwest Territories:Science Advisory Board, 1982;1-36.

11. Muir DCG, Wagemann R, Hargrave BT,Thomas DJ, Peakall DB, Norstrom RJ. Arcticmarine ecosystem contamination. Sci TotalEnviron 122:75-134 (1992).

12. Lockhart WL, Wagemann R, Tracey B,Sutherland D, Thomas DJ. Presence and impli-cations of chemical contaminants in the fresh-waters of the Canadian Arctic. Sci TotalEnviron 122:165-246 (1992).

13. Wagemann R, Snow NB, Lutz A, Scott DP.Heavy metals in tissues and organs of the nar-whal (Monodon monoceros). Can J Fish AquatSci 40(suppl 2):206-214 (1983).

14. Gamberg M, Scheuhammer AM. Cadmium incaribou and moskoxen from the CanadianYukon and Northwest Territories. Sci TotalEnviron 143:221-234 (1994).

15. Kinloch D, Kuhnlein HV, Muir DCG. Inuitfoods and diet: a preliminary assessment of ben-efits and risks. Sci Total Environ 122: 247-278(1992).

16. Innis SM, Kuhnlein HV. The fatty acid com-

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me~~~~~position of Northern-Canadian marine and ter-restrial mammals. Acta Med Scand222:105-109 (1987).

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of lead and cadmium in food composites: pre-liminary investigations. J AOAC Int 75:386-394 (1992).

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Call for Papers

International Symposium on EnvironmentalBiomonitoring and Specimen Banking

December 17-22,1995 Honolulu, Hawaii, USA

This symposium is being held as part of the International Chemical Congress of Pacific Basin Societies (PACI-FICHEM 95), sponsored by the American Chemical Society, Canadian Society for Chemistry, Chemical Society ofJapan, New Zealand Institute of Chemistry and the Royal Australian Chemical Institute.Papers for oral and poster presentations are solicited on topics that will focus on: monitoring of organic pollu-tants; monitoring of trace metal pollutants; exposure assessment; and biomarkers and risk assessment/manage-ment. The deadline for receipt of abstracts on the official Pacifichem 95 abstract form is March 31, 1995.

For further information and abstract forms, please contact:K.S. Subramanian, Environmental Health Directorate, Health Canada, Tunney's Pasture,

Ottawa, Ontario KIA 012, Canada (Phone: 613-957-1874; Fax: 613-941-4545)or G.V. Iyengar, Center for Analytical Chemistry, Room 235, B125, National Institute of Standards and Technology,

Gaithersburg, MD 20899, USA (Phone: 301-975-6284; Fax: 301-921-9847)or M. Morita, Division of Chemistry and Physics, National Institute for Environmental Studies,

Japan Environmental agency, Yatabe-Machi, Tsukuba, Ibaraki, 305 Japan(Phone: 81-298-51-6111 ext. 260; Fax: 81-298-56-4678).

746 Environmental Health Perspectives