302 VOLUME 114 | NUMBER 2 | February 2006 • Environmental Health Perspectives

Research | Mini-Monograph

Fish constitutes the main dietary protein

source for many populations worldwide.

However, the presence of methylmercury

(MeHg) in fish flesh can affect the health of

frequent fish consumers. Health risk assessment requires fitting the level of exposure of

food-borne contaminants to a mathematical

function relating exposure to effects on health

(Cronin et al. 1993). Most epidemiologic

studies dealing with the MeHg issue use mercury (Hg) levels in hair as the only indicator

of human exposure, without relating this signal to actual fish consumption patterns among

populations. The expected constant and linear

relation between MeHg oral dose and body

burden is used by government officials to

establish guidelines on safe levels of MeHg

exposure. Our objective in the present study

was to test the validity of this approach by

relating measured exposure to MeHg through

fish consumption and associated measured

levels of Hg in human hair. Using information yielded by a) a complete data set that

includes, for three distinct Canadian communities, fish consumption patterns, biomarkers

of human exposure, and related levels of Hg

in edible fish species; and b) reanalysis of other

published research related to fish consumption

and hair Hg concentrations, allowed us to

demonstrate that Hg levels in hair do not

always reflect the reported level of MeHg

intake via fish consumption, and therefore,

the expected constant and linear relation

between MeHg oral dose and body burden

seems to vary significantly among ethnic

groups. This observation could lead to questioning of regulatory policies and advisory

guidelines on fish consumption.

Materials and Methods

This study was conducted in 2002 during the

course of a broader investigation on the behavior and fate of Hg in contrasted environments,

supported by the Collaborative Mercury

Research Network (COMERN). Sports and

subsistence fishers of the Abitibi (n = 146) and

Lake St. Pierre (n = 130) regions (Quebec,

Canada), mainly of Caucasian origin, and the

First Nations people of the Innu community

(Sheshatshiu, Labrador, Canada; n = 118) were

surveyed about their dietary habits for the

3-month spring season. This period corresponds to the “camp” season for the Innu,

when they partake in the traditional way of life

in remote hunting and fishing settlements,

subsisting solely on the country food they collect, without any external supplies from market

sources. Unless otherwise specified, fish specimens used to characterize the communities’

exposure to MeHg were collected with the

help of local fishermen in the same lakes they

use for either subsistence or leisure fishing. We

collected hair samples to evaluate MeHg body

burden. We gave this biomarker priority

because it allows sequential analysis and

because it allows integration of information

based on a longer period. Blood Hg content

would reflect only recent Hg intake.

Mercury levels in fish. Total Hg levels in

fish were evaluated at the University of Quebec

in Montreal (Quebec, Canada; UQAM) and

at the Department of Fisheries and Oceans

(St. Johns, Canada). These laboratories

undergo twice-yearly interlaboratory calibration rounds administered by the Mercury

Quality Assurance Program of the Canadian

Food Inspection Agency, with analytical

variability systematically lower than 10%. A

correction factor of 0.85 was applied to all

measurements to account for the proportion

of organic versus total Hg.

A polynomial regression (Tremblay et al.

1998) was applied to normalize the relationship between fish length and Hg levels in fish

tissues. This procedure is powerful enough to

fit either linear or nonlinear regressions

between the two variables for the different

cohorts. MeHg levels used to calculate exposure were determined from the polynomial

regressions at a standardized length that correspond to the size of fish (species dependent)

regionally consumed by the participants,

according to the dietary assessments.

Dietary assessment and exposure to MeHg.

Detailed information on yearly and seasonal

fish consumption patterns were obtained using

a semiquantitative food frequency questionnaire (FFQ) developed specifically for each

community. Questions about specific fish

species consumed were incorporated into the

questionnaires devoted to the different communities. The questionnaires were pretested

with community members to evaluate content

validity. Other information, including fish

species and their origins (fishing location, market fish, canned products), were obtained.

The “fish frequency” was then calculated as

the number of meals for each specific fish

species. Each specific species frequency was

multiplied by the portion consumed (in

This article is part of the mini-monograph “Health

Effects of Mercury.”

Address correspondence to R. Canuel, COMERN,

Institute of Environmental Sciences, Université 

du Québec à Montréal, C.P. 8888, Succursale

Centre-Ville, Montréal, Québec, Canada H3C 3P8.

Telephone: (514) 987-3000, Ext. 4633. Fax: (514)

987-3635. E-mail: canuel.rene@uqam.ca

We thank the community of Sheshatshiu, especially B. Penashue, for their invaluable assistance and

cooperation. 

Results presented here were gathered through the

work of the Collaborative Mercury Research Network,

based at the University of Quebec in Montreal, and

financially supported by the National Sciences and

Engineering Research Council of Canada. 

The authors declare they have no competing financial interests.

Received 22 November 2004; accepted 24 May 2005.

New Evidence on Variations of Human Body Burden of Methylmercury 

from Fish Consumption

René Canuel,1 Sylvie Boucher de Grosbois,1,2 Laura Atikessé,1,2 Marc Lucotte,1 Paul Arp,3 Charles Ritchie,3

Donna Mergler,1,2 Hing Man Chan,4 Marc Amyot,5 and Robin Anderson6

1Institute of Environmental Sciences and 2CINBIOSE, Collaborative Mercury Research Network, Université du Québec à Montréal,

Montréal, Québec, Canada; 3Faculty of Forestry and Environmental Management, Collaborative Mercury Research Network, University

of New Brunswick in Fredericton, Fredericton, New Brunswick, Canada; 4Center for Indigenous People’s Nutrition and Environment,

Collaborative Mercury Research Network, McGill University, Ste-Anne-de-Bellevue, Québec, Canada; 5Department of Biology,

Collaborative Mercury Research Network, Université de Montréal, Montréal, Québec, Canada; 6Department of Fisheries and Oceans

Canada, Collaborative Mercury Research Network, St. Johns, Newfoundland, Canada

Epidemiologic studies commonly use mercury (Hg) level in hair as a valid proxy to estimate human

exposure to methylmercury (MeHg) through fish consumption. This study presents the results

yielded by a complete data set on fish consumption habits, Hg levels in edible fish resources, and corresponding Hg accumulation in hair, gathered in three distinct communities of eastern Canada. For

one of these communities, the average hair Hg concentration was 14 times less than the expected

value based on calculated daily oral exposure and current knowledge of MeHg metabolism. This

finding could be explained by differences in specific genetic characteristics and/or interactive effects

of other dietary components. Key words: First Nations communities, fish consumption, hair mercury

levels, human metabolism, methylmercury. Environ Health Perspect 114:302–306 (2006).

doi:10.1289/ehp.7857 available via http://dx.doi.org/ [Online 18 January 2006]
grams) that was indicated by the participant.

Examples of portion were provided, and the

equivalence in grams was derived by the

research team. In addition, local fish species

were collected, Hg levels were measured, and

mean daily Hg intakes through fish consumption were estimated. Individual Hg intake

through fish consumption were estimated

adding all frequencies × portion (grams) × fish

Hg levels for each fish species.

Hair sampling and analyses. Hair samples

were collected from participants, and Hg

concentrations were measured using a standardized protocol (Gill et al. 2002). Because

hair grows approximately 1 cm per month,

they were cut into 1-cm-long samples and

analyzed independently to establish the Hg

content. Hair strands from the root were taken

from the occipital region and then placed in

plastic bag with the root end stapled. The 3 cm

of hair corresponding to the 3 months

described in the dietary assessments were analyzed at the Laboratory Services of the First

Nations and Inuit Health Branch of Health

Canada (Environmental Research Division)

and at UQAM. Analyses of total and inorganic

Hg were performed according to the method

described in Farant et al. (1981). Analytical

quality control was ensured with standard hair

samples, provided by the Hair Mercury

Interlaboratory Comparison Program of

Health Canada. Both laboratories participate

twice each year in the interlaboratory calibration program Hair Mercury Proficiency

Testing Program of Health Canada, with

analytical variability systematically lower than

10% (Gill et al. 2002).

Simulation runs. Starting with the extensive quantitative analysis made by the National

Research Council (NRC 2000) on Hg toxicology and metabolic dose response that became

the main reference in this field of Hg science,

we assembled a graphic interfaced STELLAbased one-compartment model (ISEE Systems,

Lebanon, NH, USA) that offers a convenient

way to test the relationships of various data sets

on human MeHg exposure presented by the

NRC. It provides for this study a simple and

practical tool to compare the relative response

of groups to certain levels of Hg exposure rather

than an absolute prediction method. The wellestablished toxicokinetics parameters used by

the model are presented in Table 1 (NRC

2000; Rice et al. 2003; U.S. Environmental

Protection Agency 1997). We successfully

tested and validated this particular rendering of

the NRC’s work against experimental data sets

and other existing models on human response

to MeHg exposure (Birke et al. 1972; Carrier

et al. 2001; Kershaw et al. 1980; Sherlock et al.

1984). This tool was used to assess and compare our experimental data sets of the ratios of

dose (or exposure to MeHg) to response (or

hair Hg levels) of the different communities

involved in this study with the values that could

be expected from the widely recognized knowledge on Hg metabolic behavior and rates

yielded by the model’s outputs.

Results

Table 2 presents the calculated daily exposure

for the 3-month spring season for the three

populations as well as a comparison between

the simulated and mean measured Hg hair

values corresponding to the same period. There

is close agreement between the measured Hg

levels in hair and estimated values from the

model in Abitibi and the Lake St. Pierre region

(estimated average within the range of the 

standard deviation of hair measurements).

However, in Labrador, the estimated average

hair Hg concentration was > 14-fold the measured value. Furthermore, the ratios of mean

measured hair Hg level to calculated daily exposure differ by a factor of > 10 between the Innu

and the Lake St. Pierre cohort and a factor of 7

between the Innu and the Abitibi cohort,

which contradicts the constant relation between

exposure and hair Hg levels expected according

to accepted theories.

To confirm this observation, we gathered

and reanalyzed published but separate data sets

of Hg levels in hair in different communities,

and then information on their dietary habits

and plausible sources and levels of Hg exposure. Only data sets that contain information

sufficient to build reasonable scenarios on fish

consumption patterns and contamination were

included. Results of simulation runs on measured and estimated Hg levels in hair for these

populations are presented in Table 3.

One of the most complete data sets of hair

Hg concentrations and fish consumption

patterns is reported by Lebel et al. (1997) and

Dolbec et al. (2001), who documented the

behavior of riparian populations living along the

shores of the Tapajòs River in the middle of the

Brazilian Amazon. Hair Hg signal simulated by

the model using their field data is consistent

with the observed field hair Hg levels and within

100% of the measured concentration.

However, estimated hair Hg levels for the

different aboriginal people communities 

of Canada (Nunavik, Eastmain, and White

Dog) presented in Table 3 were about 500%

higher than the measured concentrations.

Interestingly, similar variation was observed

using data sets published by Yasutake et al.

(2004) and obtained in different populations in

Japan (Table 3). Nakagawa et al. (1997) also

reported a mean Hg intake of 170 μg Hg/week

from fish and shellfish for the Japanese population, which would correspond, using our

model, to a Hg hair signal of 6.7 ppm (compared with an average measurement of

1.8 ppm; Yasutake et al. 2004).

Discussion

In this study, using validated tools and 

procedures, we found that for the Innu community, Hg levels in hair did not reflect the

reported level of MeHg intake via fish consumption. The discrepancies between the

measured Hg levels in biomarkers and the

modeled Hg levels could be questioned considering that many sources of variability,

including instrumental and reporting bias,

may have been introduced into the design of

the study and/or analysis of the results.

Human hair mercury levels and fish consumption

Environmental Health Perspectives • VOLUME 114 | NUMBER 2 | February 2006 303

Table 2. Simulation runs for the three regions under study.

Calculated daily Measured Hg Ratio between Modeled Hg levels

exposure levels in hair Hg hair levels and in hair using

Region (μg Hg/day/kg bw)a (ppm; first 3 cm) calculated exposure exposure (ppm)

Lake St. Pierre 0.068 0.83 12.2 1.2

(n = 130) (0.109)b (0.97)c (0.33)d

(0.018)d (0.17)d

Abitibi 0.139 1.2 8.6 2.3

(n = 146) (0.183)b (1.40)c (0.49)d

(0.30)d (0.23)d

Labrador 0.342 0.4 1.2 5.7

(n = 118) (0.242)b (0.36)c (0.73)d

(0.044)d (0.065)d

bw, body weight

aMeasurements were performed on Hg levels in local species at standardized edible length, and canned tuna. Mercury

data for market fish are from Dabeka et al. (2003). bSD on average values, calculated from the variability associated with

individual numbers of fish meals per species for the sampling season; an additional factor of 10% can be considered to

account for the analytical uncertainty related to fish Hg level determinations. cSD on the general mean of individual averaged hair Hg levels for the 3 cm corresponding to the dietary assessments; an additional factor of 10% can be considered

to account for the analytical uncertainty related to hair Hg level determinations. d95% confidence limit (Colton 1974).

Table 1. Pharmacokinetic parameters used in the

STELLA model.

Parameter Value

Half-life of Hg in body 70

Maximum Hg input from tooth amalgam (μg/day) 21

No. of teeth with amalgam fillings 12

(maximum = 32)

Body absorption rate of inorganic Hg2+ 0.15

Body absorption rate of inorganic Hg0 (μg/day) 0.03

Hg accumulation in the liver 70%

Hg accumulation in the brain 10%

Ratio of hair-to-blood Hg levels 250

Rate of hair growth (cm/day) 1.1

Hair to emerge from scalp (days) 20

Data from NRC (2000).
Analytical variability and determination of

fish MeHg levels. Based on interlaboratory calibration rounds administered by the Mercury

Quality Assurance Program of the Canadian

Food Inspection Agency, and on the Hair

Hg Proficiency Testing Program of Health

Canada, analytical variability related to the Hg

quantification in fish and in hair samples is

< 10%, which leads to a quite accurate evaluation of Hg content in fish and in hair samples.

All hair Hg measurements were performed on

representative samples, using recognized analytical techniques (Gill et al. 2002). Fish Hg data

used to estimate exposure levels are mainly

either from direct field measurements in the

lakes harvested by the communities to minimize interlake variability or from otherwise

well-documented sources. Furthermore, we

elected to normalize the fish Hg levels through

a polynomial regression between fish length

and Hg levels to a) compensate for fluctuations

of fish Hg levels with length, with the bigger

fish usually having higher Hg levels; b) account

for intralake variability of fish Hg levels for a

given species; and c) extrapolate specific fish

Hg levels at edible length as reported in the

regional dietary assessments. To our knowledge, the estimates calculated using this protocol remain among the most accurate in the

available population-scale studies.

Variability related to exposure assessment.

In Labrador the period sampled corresponds

to the “spring camp” season for the Innus. For

this 3-month period they live isolated in

remote hunting and fishing settlements, without external food supplies and subsisting solely

on their fish and wildlife harvest. Dietary

information for the Innus was gathered just

after this period, reducing recall bias. In this

community no advisory promoting fish consumption was under way. Therefore, social

and/or cultural pressure to report traditional

food habits could not account for a potential

overreporting bias. Detailed information was

gathered to provide an exhaustive dietary profile and a good evaluation of fish Hg content

based on actual fish species lengths and fishing

sites reported by the participants.

Dietary survey, which may include reporting bias of participants, would result in overor underestimation of intake. Variability in

self-reported dietary intake threatens inferences

from studies relying on instruments such as

FFQs. Several authors have addressed the

issues of reliability and validity of FFQ as estimators of dietary patterns (Horner et al. 2002;

Hu et al. 1999; Kipnis et al. 2002; Shatenstein

et al. 1999). Studying the reliability and relative validity of fish consumption data obtained

in an exposure assessment study among sport

fishers in the Montreal area, Shatenstein et al.

(1999) conclude that the FFQ provides a reliable and relatively accurate indication of sportfisher fishing practices, species selection, and

sport-fish consumption habits. In this study

ascertainment of the consistency of estimated

portion sizes and number of fish meals was

performed during a two-season exercise over

2 years. Elsewhere, studying the reproducibility

and validity of dietary patterns assessed with an

FFQ, Hu et al. (1999) found good reliability

correlation coefficients (0.70). Validity analysis, comparing FFQs with diet records (gold

standard), showed moderate to good correlation coefficients for fish and other seafood

(0.51–0.74). The authors concluded that the

major dietary patterns derived from the FFQ

have reasonable reproducibility and validity.

However, only men were included in their

sample. A study conducted in a group of postmenopausal women also concluded reliable

and accurate measure of usual intake of major

nutrients and food groups among women in

Shanghai (Xu et al. 2004). In a study designed

to evaluate the reliability and validity of an

FFQ for low-income Mexican Americans,

McPherson et al. (1995) found correlation

coefficients ranging from 0.61 to 0.77, comparing results obtained from FFQ with 3-day food

records. Reliability correlation coefficients calculated after a 2-month interval ranged from

0.85 to 0.90. These high correlation coefficients

were explained by the authors as the lack of

diversity in the diets of the participants.

However, different results were found by

Horner et al. (2002) and Kipnis et al. (2002).

In a postmenopausal study (n = 102), Horner

et al. (2002) showed that underreporting

appeared to be relatively high. However, this

variation seemed to be explained mainly by

participant characteristics, and evidence suggested more underreporting among women

who were younger or had high social desirability score. Kipnis et al. (2002), in a study aimed

to evaluate measurement error structure in

dietary assessment instruments using urinary

nitrogen excretion as a reference biomarker for

protein intake, showed overestimation (up to

230%) and underestimation (up to 240%) of

FFQ. However, even in this worse-case scenario, such variability would not explain the

14-fold difference observed in our study

between the observed Hg level in hair and the

expected values.

NRC model. Intrapopulation variability 

of human metabolic handling of MeHg has

been reported in most epidemiologic studies

addressing the issue. Pharmacokinetic constants were reported to vary extensively

between individuals and between groups. This

variability yielded the greatest uncertainties for

its predictions. For example, the ratio used by

the NRC between Hg content of hair versus

blood is 250 but ranged elsewhere from 140

to 370 (Bartlett et al. 2000; World Health

Organization 2003), or roughly +48%/–45%.

Likewise, the generally recognized value for

whole-body half-life of organic Hg is 70 days

(also used by NRC), but this number is

reported to vary between 44 and 80 days

Canuel et al.

304 VOLUME 114 | NUMBER 2 | February 2006 • Environmental Health Perspectives

Table 3. Simulation runs for other populations.

Estimated Hg Average daily Modeled Hg Measured Hg

level in local Hg intake level in hair level in hair

Population fish (ppm) (μg Hg/day/kg bw)a (ppm) (ppm) Variability (%)

Tapajosb Brazil, 0.2 0.50 8.5 Median, 12.5 68

1996 (n = 36 women)

Nunavikc Canada, 0.5 1.07 18.1 3.8 476

First Nations Inuit,

1992 (n = 492)

Eastmaind Canada, 1.1 1.37 23.4 50th percentile ~ 400

First Nations Cree, > detection limit

1988 (n = 144) of 2.5, 95th

percentile > 6

White Doge Canada, NA 1.53 25.8 4.5 573

First Nations Ojibwa,

2003 (n = 48)

Japan,f Miyagi district, 0.5 0.80 13.5 2.3 586

1999–2002 (n = 1,185)

Japan,f Okinawa district, 0.5 0.35 5.9 1.6 369

1999–2002 (n = 1,019)

Japan,f 10 districts, 0.5 0.49 8.3 1.8 461

1999–2002 (n = 8,665)

aBody weight (bw), 60 kg for Japanese and Brazilians; others, 70 kg.bCalculated from field data on consumed fish species

(Lebel et al. 1997) and Hg levels in fish (Dolbec et al. 2001). cMean fish Hg level reasonably set to 0.5 ppm, according to levels of contamination of food traditionally consumed by Inuits (Wagemann et al. 1998) and consumption frequency (Dewailly

et al. 2001a): seal liver, 19 ppm; seal muscle, 0.6 ppm; arctic char, frequently > 0.5 ppm; lake trout, frequently > 0.5 ppm;

whitefish, frequently > 0.5 ppm; white whale skin, > 0.5 ppm; beluga muscle, 1.04 ppm; beluga liver, 10.1 ppm. Blood

measurement in Dewailly et al. (2001b) converted in hair signal using a hair:blood ratio of 250 (Schwartz 1999). dEstimated

according to Cree consumption habits: 20% of total diet from fish (Hydro-Quebec 2001); proposed diet (Hg levels in Dumont

et al. 1998): one-fifth each whitefish from LaGrande 2 reservoir (Quebec), 0.5 ppm; whitefish, Eastmain river, 0.4 ppm; pike,

LaGrande 2 reservoir, 3 ppm; pike, Eastmain river, 0.8 ppm; white sucker, LaGrande 2 reservoir, 0.8 ppm. Hair Hg levels are

from Schetagne and Verdon (1999). eCalculated from data set on consumption frequency and Hg levels in fish (Chan LHM,

personal communication). f Consumption frequency and Hg hair measurements are from Yasutake et al. (2004) and

Nakagawa et al. (1997); mean fish Hg level reasonably set to 0.5 ppm, considering frequency of tuna consumption and type

of tuna consumed, leading to an estimated mean tuna Hg level of 1.1 ppm. 
Human hair mercury levels and fish consumption

Environmental Health Perspectives • VOLUME 114 | NUMBER 2 | February 2006 305

(Willes 1977; World Health Organization

2003), or roughly +15%/–63%. This variability is taken into account by existing norms

through the inclusion of uncertainties factors

used by risk assessment models to limit specific risks that could emerge from individuals’

divergence from averaged dose–response ratio.

However, although intrapopulation heterogeneity makes consensus, it is to our knowledge the first time that a homogeneous

divergent signal among a population such as

the one measured in the Innu community is

reported. This discrepancy is significant and

cannot be accounted for by the model’s variability, even if considered as rather improbable

best-case scenarios (half-life, 44 days;

hair:blood ratio, 370) or worst-case (half-life,

80 days; hair:blood ratio, 140).

Other simulations. Finally, the scenarios

describing consumption frequencies for the

Inuit and Cree communities reported in

Table 3 were established taking into account

both published and traditional knowledge of

communities’ eating habits, as well as the presence of alternate food sources that could

replace local fish resources, and carry biases on

our estimates. Both the Inuit and Cree communities live in remote, secluded locations and

rely heavily on subsistence living. The Inuits

exhibit opportunistic feeding habits, based on

occasional availability of food sources, for

example, frequently feeding on mammals

(seals, whales) for extended periods, after fruitful hunts. On the other hand, the Cree study

was performed in 1988, which corresponds to

the climax period for both the exploitation of

the newly impounded reservoirs from the

La Grande river complex by the community

and peak contamination of the reservoirs’ fish

resource by Hg (Schetagne and Verdon 1999).

For these reasons we feel that the above

estimates are realistic.

Conclusion

Considering that reanalysis of published data

are presented solely in the context of supporting strong evidence from field data, we suggest

that, contrary to well-received, accepted, and

commonly used scientific precepts, the relation

between MeHg oral dose and body burden—

expressed as human MeHg exposure through

fish consumption versus Hg levels in hair—

may vary among certain ethnic groups. Several

possible hypotheses are proposed to explain

this observation.

The nature (density, molecular structure,

growth rate) of hair might differ between ethnic

groups. However, we could not observe any

statistical difference in hair weight per centimeter between the Labrador, Lake St. Pierre,

and Abitibi cohorts. Other observations

(Wolfram 2003) also suggest that hair molecular structure should not differ to a great extent

between the groups.

Mercury metabolic excretion rates might

vary according to ethnicity. It is well recognized

that Japanese, Vietnamese, Chinese, and First

Nations populations, which are of Asian ancestry, experience a genetic polymorphism for

enzymes ALDH2 and glutathione S-tranferase

involved in ethanol metabolic excretion and Hg

export from human cells (Strange et al. 2000;

Walsh et al. 2001; Yokoyama et al. 2002).

These genetic polymorphisms could affect elimination rate. Animal studies provide evidence

for a major role of γ-glutamyl transpeptidase

(GGT) in regulating the tissue distribution and

elimination of MeHg in GGT-deficient mice

(Ballatori et al. 1998). Differences in enzymatic

expression might result in differential metabolic

process of MeHg. Currently, no study has been

designed to address those interactions in human

populations. Therefore, the extent to which

interpopulation variability in biomarkers at

similar doses is attributable to genetic differences in susceptibility remains unknown.

Combined effects of specific metabolic

processes or specific components present in the

diet of the above populations after particular

traditional food consumption and/or cooking

habits, might decrease the metabolic absorption

or increase the excretion of MeHg. If proven,

this hypothesis would culminate in reduced

health risks associated with fish consumption.

Regardless of the factors explaining the

above observations, the impact of the evidence

presented here on normative policies regarding

safe levels of MeHg exposure is obvious. The

current regulation guidelines used by both

national and international agencies are based

on the assumption that hair Hg concentration

is a valid indicator of oral dose and toxic end

points for all populations. If this assumption

is proven invalid and as suggested by our

findings, the actual guidelines must be fish

consumption do not fully reflect the true metabolic response of different ethnic communities

to the presence of Hg in their food source, and

fish consumption advisory guidelines have to

be redrafted using information collected specifically from local communities. Considering the

importance of fish as a protein source for many

First Nations communities and/or subsistence

fishers, further assessment is needed to properly

inform consumers frequently enjoying fish

meals about the health costs–benefits related to

fish consumption.

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