Aboriginal Health Risk Assessment of Mercury in Bull Trout Harvested from the Crooked River, British...

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Aboriginal Health Risk Assessmentof Mercury in Bull Trout Harvestedfrom the Crooked River, British Columbia

March 2015

Prepared for:

West Moberly First Nations

Aboriginal Health Risk Assessment of Mercury in Bull Trout Harvested from the Crooked River, British Columbia

March 2015

Project #0276885-0006

Citation: ERM. 2015. Aboriginal Health Risk Assessment of Mercury in Bull Trout Harvested from the Crooked River, British Columbia. Prepared for West Moberly First Nations by ERM Consultants Canada Ltd.: Vancouver, British Columbia.

ERM ERM Building, 15th Floor 1111 West Hastings Street Vancouver, BC Canada V6E 2J3 T: (604) 689-9460 F: (604) 687-4277

ERM prepared this report for the sole and exclusive benefit of, and use by, West Moberly First Nations. Notwithstanding delivery of this report by ERM or West Moberly First Nations to any third party, any copy of this report provided to a third party is provided for informational purposes only, without the right to rely upon the report.

WEST MOBERLY FIRST NATIONS i

EXECUTIVE SUMMARY

TEK of the West Moberly provided the basis for the assessment of risk to human health due to consumption of Bull Trout from the Crooked River system. Given the connectivity of the Crooked River system to the Williston Reservoir where a fish advisory is in place due to mercury, there was concern that mercury concentrations in fish harvested from this river system would also be elevated. Therefore, a preliminary quantitative HHRA focused on mercury was done to determine what, if any, risk there is to human health due to consumption of Bull Trout from the Crooked River system. The HHRA followed standard Health Canada guidance. The preliminary HHRA focused on First Nation consumers, including consideration of traditional practices and consumption patterns.

Traditional practices related to fish consumption may include attendance at Fish Camps. Fish Camps are periods of time in the late spring or early summer where people gather together and a number of Bull Trout are harvested. Fish may be either consumed immediately or taken home for later consumption. Fish harvested by attendees of the Fish Camps are kept for personal consumption throughout the year, distributed to other family or community members, or potentially used for trade or sale to others in accordance with the cultural mode of life. Fish may be consumed by people of all ages and both genders, either fresh (i.e., freshly caught or from the freezer), or dried (e.g., smoked or otherwise dried).

Samples of Bull Trout (n = 57) from the Crooked River system and Northern Pikeminnow (n = 3) from McLeod Lake were collected in 2012, and analyzed for age and tissue metal concentrations. Fish were also measured and weighted. Results indicate that the average age of Bull Trout sampled in 2012 was approximately 7 years old (95th percentile age was 10 years old). The average fish length was 521 mm (95th percentile was 780 mm), and the average weight was 1.78 kg (95th percentile was 4.7 kg). A significant correlation was found between the concentration of mercury in fish and the age, length, and weight of the fish. Generally, as the fish become older or larger, the tissue concentrations of mercury increase. It is assumed that all of the mercury in the fish was in the more toxic methylmercury form.

The concentrations of mercury measured in the tissue of Bull Trout and Northern Pikeminnow were relatively high. All of the Northern Pikeminnow and 37% of the Bull Trout had tissue mercury concentrations that exceeded the Health Canada Maximum Contaminant Standard and the British Columbia Ministry of Environment (BC MOE) guideline of 0.5 mg/kg wet weight (ww). In comparison to the most permissive BC MOE guideline for fish tissue of 0.1 mg/kg ww (which is based on the consumption of approximately 1 kg of fish per week), 98% of the Bull Trout had tissue mercury concentrations that exceed the guideline. This data is also summarized in Table 1. Since many of the fish sampled in 2012 had mercury concentrations greater than guidelines, it suggests that there could be risk to human health, particularly in people with high consumption rates for fish.

ABORIGINAL HEALTH RISK ASSESSMENT OF MERCURY IN BULL TROUT HARVESTED FROM THE CROOKED RIVER, BRITISH COLUMBIA

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Table 1. BC Ministry of Environment Aquatic Life Guidelines for Mercury in Fish and Comparison with Measured Mercury Tissue Residues from Bull Trout

Total Mercury Concentration in the Edible Portion (mg/kg ww)

Safe Quantity for Weekly Consumption

(kg)

Percentage of Bull Trout Sampled in May 2012 with Tissue Residues

Greater than Guideline

0.5a 0.210 37%

0.4 0.260 46%

0.3 0.350 61%

0.2 0.525 88%

0.1 1.050 96%

Note: mg = milligram, kg = kilogram, ww = wet weight a The BC Ministry of Environment guideline of 0.5 mg/kg ww of fish is the same as the Health Canada Maximum Contaminant Standard for Mercury in fish tissue.

When mercury in food is taken into the human body in high enough quantities, adverse effects to human health are possible. The most sensitive population for mercury toxicity is the unborn fetus, where exposure occurs due to unintentional intake of mercury by the pregnant woman, and development effects can occur in the child after birth. Therefore, pregnant women, women of child-bearing age who may become pregnant, toddlers, and children under 12 are considered to be the most sensitive populations for mercury exposure. The provisional tolerable daily intake (pTDI) of methylmercury that is considered tolerable for intake by sensitive populations, without causing adverse effects, is 0.0002 milligrams per kilogram body weight per day (mg/kg bw/day).

Other potential effects of mercury could occur in the general population at higher concentrations, such as effects on the immune system, cardiovascular system, or nervous system. The amount of methylmercury considered tolerable for intake by the general population, without causing adverse effects, is slightly higher at 0.00047 mg/kg bw/day.

Further analysis of the risk to human health was done by calculating a recommended maximum weekly intake (RMWI) for Bull Trout. Since this study is intended to be a preliminary assessment of risk, the 95th percentile of mercury concentrations in Bull Trout from 2012 were used to ensure that the calculations are protective of health. The RMWIs incorporated traditional practices of West Moberly, particularly the consumption patterns of fish (i.e., high frequencies of fish consumption during Fish Camp, lower frequency throughout the rest of the year) and how fish are prepared for consumption (i.e., fresh or dried).

RMWIs calculated based on the 95th percentile of mercury concentrations suggest that consumption of fresh Bull Trout for the general population (i.e., those individuals not in a sensitive group) during the Fish Camps should be kept below 0.292 kg fish/week. The RMWIs for fresh Bull Trout are lower for those in the sensitive groups, ranging from 0.025 kg fish/week for toddlers, 0.046 kg fish/week for children under 12 years of age, and 0.106 kg fish/week for women of childbearing age or those who are pregnant. Consumption of dried fish should be kept lower since drying removes moisture without removing mercury; RWMIs ranged between 0.011 kg/week for toddlers up to 0.129 kg/week in the general population. These RMWIs are also shown graphically in Figure 1. It is probable that people are consuming more fish than is recommended during the Fish Camps.

WEST MOBERLY FIRST NATIONS

Recommended Maximum Weekly Intake of Bull Trout based on 95th Percentile Mercury Concentrations

Figure 1

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Similarly, during the remainder of the year, the RMWI of Bull Trout for the general population based on the 95th percentile of mercury concentrations for fresh fish is 0.058 kg/week and for dried fish is 0.026 kg/week. The RMWIs are lower for those in the sensitive groups, ranging from 0.005 kg/week fresh fish or for toddlers, 0.009 kg fish/week for children under 12 years of age, and 0.021 kg fish/week for women of childbearing age or those who are pregnant. For dried fish, the RMWIs are 0.002 kg/week for toddlers, 0.004 kg/week for children under 12, and 0.009 kg/week for sensitive adults. These RMWIs are also shown graphically in Figure 1. It is probable that people are consuming more fish than is recommended during the time of year outside of the Fish Camp, particularly for people in the more sensitive groups.

Hazard quotients were also calculated, based on a ratio of the estimated daily intake of mercury and the pTDI. When the HQ is greater than 1.0, there could be a risk to human health and additional investigation should be conducted. During the Fish Camps, the HQs ranged from 31.9 in the general population to 183.8 in toddlers, based on the consumption rates (4 kg per 3 days for adults attending Fish Camps) provided during interviews with participants from West Moberly. During the remainder of the year (assuming a consumption frequency of once per week), the HQs ranged from 2.8 in the general population to 16.1 in toddlers. These HQs suggest that there could be risk to human health from the consumption of Bull Trout from the Crooked River system.

Consumption of fish has many benefits to health, including physical, mental, cultural, and spiritual well-being. It is important that people consider both the risks and the benefits of fish consumption in order to make the most informed decisions about whether or not fish should be eaten.

Based on the findings of this preliminary quantitative HHRA, a number of recommendations for additional work were made. This includes the urgent need to communicate these results to individuals who would be considered to have high fish consumption rates and could be at risk of adverse effects due to mercury. Other recommendations include studies to define the temporal and spatial trends, monitoring of other fish species, a more detailed assessment of risk to human health, and preliminary risk assessment for wildlife consumers of fish and for fish health.

WEST MOBERLY FIRST NATIONS v

ACKNOWLEDGEMENTS

This report was produced for West Moberly First Nations by ERM Rescan. It was written by Bruce Muir (M.A.) and Dr. Lesley Shelley (Ph.D., R.P.Bio), with statistical analysis (regression analysis and associated figures) provided by Dr. Kerry Marchinko (Ph.D., R.P.Bio) using the statistical program R. The report was technically reviewed by Sharon Quiring (M.Sc., CIH). Bruce Muir was the project manager and Dr. Kent Gustavson (Ph.D) was the Partner-in-Charge. GIS maps were prepared by Mike Stead, and graphics were prepared by Francine Alford and Jason Widdes. The report was published by Lloyd Majeau.

The authors would like to thank Chief and Council and the Land Use Department for providing ERM with the opportunity to work with West Moberly and its members. We would also like to thank First Nations Health Authority (Environmental Contaminants Program) for providing the funding for the study. A special thank you goes to the members of McLeod Lake Indian Band and West Moberly First Nations that participated in the study. Without their contributions the study would not have been possible.

Plate 1. Participants in the Fish Study

WEST MOBERLY FIRST NATIONS vii

WEST MOBERLY FIRST NATIONS FISH CONTAMINANTS STUDY Aboriginal Health Risk Assessment of Mercury in Bull Trout Harvested from the Crooked River, British Columbia

TABLE OF CONTENTS

Executive Summary ............................................................................................................................................ i

Acknowledgements ........................................................................................................................................... v

Table of Contents .............................................................................................................................................vii List of Figures ...................................................................................................................................... ix List of Tables ........................................................................................................................................ ix List of Plates .......................................................................................................................................... x List of Appendices............................................................................................................................... xi

Abbreviations ..................................................................................................................................................xiii

1. Introduction and Approach to Assessment ................................................................................... 1-1 1.1 Overview .............................................................................................................................. 1-1 1.2 Study Area ............................................................................................................................ 1-1 1.3 Human Health Risk Assessment Framework .................................................................. 1-1

2. Problem Formulation ........................................................................................................................ 2-1 2.1 Data Used to Support the Risk Assessment ..................................................................... 2-1

2.1.1 Traditional Ecological Knowledge ...................................................................... 2-1 2.1.2 Fish Tissue Metals, Fish Age, and Other Biological Data ................................. 2-4

2.1.2.1 Analytical Testing ................................................................................. 2-5 2.2 Scope of the Risk Assessment Conceptual Model ........................................................ 2-6

2.2.1 Preliminary Estimate of Distribution of Bull Trout in the Study Area ........... 2-6

3. Exposure Assessment ....................................................................................................................... 3-1 3.1 Human Receptor Groups .................................................................................................... 3-1 3.2 Concentration of Mercury in Fish ..................................................................................... 3-2

3.2.1 Concentrations based on the Summary Statistics .............................................. 3-2 3.2.2 Concentrations based on the Use of Regression Relationships ....................... 3-5

3.3 Estimated Daily Intake ........................................................................................................ 3-9


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3.3.1 Serving or Portion Sizes ...................................................................................... 3-10 3.3.2 Patterns in Fish Consumption (Frequency of Consumption) ........................ 3-12

4. Toxicity Assessment .......................................................................................................................... 4-1 4.1 Potential Effects on Human Health due to Mercury ...................................................... 4-1 4.2 Provisional Tolerable Daily Intake .................................................................................... 4-2 4.3 Adjustment of the Provisional Tolerable Daily Intake to Account for Fish

Consumption Patterns based on Traditional Practices .................................................. 4-3

5. Risk Characterization ........................................................................................................................ 5-1 5.1 Comparison of Fish Tissue Mercury Concentrations to Tissue Residue

Guidelines ............................................................................................................................. 5-1 5.1.1 Health Canada Maximum Contaminant Standard for Mercury in Fish

Tissue ....................................................................................................................... 5-1 5.1.2 BC Ministry of Environment Aquatic Life Guidelines for Mercury in

Fish Tissue ............................................................................................................... 5-2 5.1.3 Conclusions based on Comparison of Mercury Measured in Fish Tissue

and the Fish Tissue Residue Guidelines ............................................................. 5-3 5.2 Recommended Maximum Weekly Intake ........................................................................ 5-4

5.2.1 Calculation of Recommended Maximum Weekly Intake based on the 95th Percentile of Mercury Concentrations ......................................................... 5-5

5.2.2 Calculation of Recommended Maximum Weekly Intake based on Fish Length ...................................................................................................................... 5-7

5.2.3 Calculation of Recommended Maximum Weekly Intake based on Fish Weight ................................................................................................................... 5-10

5.2.4 Summary and Conclusions based on Recommended Maximum Weekly Intakes for Bull Trout........................................................................................... 5-12 5.2.4.1 Consumption of Bull Trout during the Fish Camps ...................... 5-12 5.2.4.2 Consumption of Bull Trout during the Remainder of the Year ... 5-13

5.3 Calculation of Hazard Quotients ..................................................................................... 5-14 5.4 Fish Consumption Advisory for the Williston Reservoir ............................................ 5-15 5.5 Summary and Conclusions from Risk Characterization .............................................. 5-18

6. Importance of Fish Consumption and Traditional Practices to Health ..................................... 6-1

7. Assumptions, Uncertainties, and Limitations ............................................................................... 7-1 7.1 Fish Tissue Sampled for Laboratory Analysis ................................................................. 7-1 7.2 Sample Size of Fish .............................................................................................................. 7-1 7.3 Proportion of Methylmercury ............................................................................................ 7-1 7.4 Selection of Potential Receptors ......................................................................................... 7-1 7.5 Human Receptor Groups and Receptor Characterization ............................................. 7-2

TABLE OF CONTENTS

WEST MOBERLY FIRST NATIONS ix

7.6 Contaminants of Potential Concern .................................................................................. 7-3 7.7 Mercury Tissue Concentration Guidelines ...................................................................... 7-3 7.8 Adjustment of Methylmercury Provisional Tolerable Daily Intake based on

Consumption Patterns ........................................................................................................ 7-4

8. Summary and Recommendations ................................................................................................... 8-1 8.1 Summary and Conclusions ................................................................................................ 8-1 8.2 Recommendations ............................................................................................................... 8-3

References ....................................................................................................................................................... R-1

LIST OF FIGURES

Figure 1. Recommended Maximum Weekly Intake of Bull Trout, based on the 95th Percentile of Mercury Concentrations. ............................................................................................................... iii

Figure 1.2-1. Study Area for the Aboriginal Fisheries in the Crooked River System ........................... 1-2

Figure 2.1-1. Fish and the Traditional Seasonal Round ............................................................................ 2-2

Figure 2.2-1. Potential Access Barriers for Bull Trout in the Williston Reservoir and its Tributaries .......................................................................................................................................... 2-7

Figure 3.2-1. Mercury Tissue Concentrations (in mg/kg ww) Measured in Individual Bull Trout and Northern Pikeminnow, May 2012 ................................................................................ 3-3

Figure 3.2-2. Frequency Distribution of the Mercury Tissue Concentrations (in mg/kg ww) Measured in Bull Trout, May 2012 .................................................................................................. 3-4

Figure 3.2-3. Regression Relationship between Age (in years) and Mercury Tissue Concentrations (in mg/kg ww) for Bull Trout ............................................................................. 3-6

Figure 3.2-4. Regression Relationship between Length (in mm) and Mercury Tissue Concentrations (in mg/kg ww) for Bull Trout ............................................................................. 3-7

Figure 3.2-5. Regression Relationship between Weight (in kg) and Mercury Tissue Concentrations (in mg/kg ww) for Bull Trout ............................................................................. 3-8

LIST OF TABLES

Table 1. BC Ministry of Environment Aquatic Life Guidelines for Mercury in Fish and Comparison with Measured Mercury Tissue Residues from Bull Trout ..................................... ii

Table 3.2-1. Mercury Tissue Concentrations in Bull Trout and Northern Pikeminnow from the Crooked River system, May 2012 .................................................................................................... 3-2

Table 3.3-1. Values Used in the Calculation of Estimated Daily Intake ............................................... 3-10


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Table 5.1-1. Length and Weight of Bull Trout Estimated to have Tissue Concentrations of Mercury Exceeding Health Canada Maximum Contaminant Standard ................................... 5-2

Table 5.1-2. BC Ministry of Environment Aquatic Life Guidelines for Mercury in Fish and Comparison with Measured Mercury Tissue Residues from Bull Trout .................................. 5-2

Table 5.1-3. Length and Weight of Bull Trout Estimated to have Tissue Concentrations of Mercury Exceeding BC Ministry of Environment Tissue Residue Guidelines ......................... 5-3

Table 5.2-1. Recommended Maximum Weekly Intake of Bull Trout based on Summary Statistics and Human Receptor Group ........................................................................................... 5-6

Table 5.2-2. Recommended Maximum Weekly Intake of Bull Trout during the Fish Camps based on Fish Length and Human Receptor Group ..................................................................... 5-8

Table 5.2-3. Recommended Maximum Weekly Intake of Bull Trout during the Remainder of the Year based on Fish Length and Human Receptor Group ..................................................... 5-9

Table 5.2-4. Recommended Maximum Weekly Intake of Bull Trout during the Fish Camps based on Fish Weight and Human Receptor Group .................................................................. 5-11

Table 5.2-5. Recommended Maximum Weekly Intake of Bull Trout during the Remainder of the Year based on Fish Weight and Human Receptor Group ................................................... 5-12

Table 5.3-1. Risk Characterization for Mercury Intake from Bull Trout during Fish Camps and Remainder of the Year .................................................................................................................... 5-15

LIST OF PLATES

Plate 1. Participants in the Fish Study ............................................................................................................ v

Plate 2.1-1. Example of bait (i.e., Peamouth) used by West Moberly to catch Bull Trout on the Crooked River, BC. ............................................................................................................................ 2-3

Plate 2.1-2. Fish harvested via gill nets at culture camps in the Study Area during the summer months. ............................................................................................................................................... 2-3

Plate 2.1-3. Example of Bull Trout harvested from the Crooked River, BC. .......................................... 2-4

Plate 2.1-4. Photo of fish sampling, including measurement of fish length and weight, September 2012 .................................................................................................................................. 2-5

Plate 3.1-1. Youth at the Fish Camp on the shores of the Crooked River, BC. ...................................... 3-1

Plate 3.3-1. Example of how traditional foods are provided at culture camps. Meats are prepared in different traditional ways throughout the day and evening for participants and visitors to eat when they are hungry. ................................................................................... 3-11

Plate 3.3-2. West Moberly member with Bull Trout that were prepared for consumption at a later date. .......................................................................................................................................... 3-13

TABLE OF CONTENTS

WEST MOBERLY FIRST NATIONS xi

Plate 4.3-1. Bull Trout harvested in the fall season from the Carbon Creek, south of the Peace Reach of the Williston Reservoir. .................................................................................................... 4-4

Plate 4.3-2. Lake Trout harvested by West Moberly members. ............................................................... 4-4

Plate 5.2-1. Youth (i.e., under 12 years of age) with a Bull Trout harvested from the Crooked River, BC, in 2008 at Fish Camp. ..................................................................................................... 5-4

Plate 5.2-2. Bull Trout harvested by a youth during the fall season in the Peace region. .................... 5-5

Plate 5.4-1. Pre-Construction and Flooding BC Hydros W.A.C. Bennett Hydroelectric Dam and the Williston Reservoir. .......................................................................................................... 5-16

Plate 5.4-2. Post-Construction and Flooding BC Hydros W.A.C. Bennett Hydroelectric Dam and the Williston Reservoir. .......................................................................................................... 5-16

Plate 5.4-3. Example of a non-aboriginal youth that harvests Bull Trout ............................................ 5-17

Plate 6-1. Father teaching his sons West Moberlys TEK regarding safety and respect for the land, family history, and fishing practices regarding Bull Trout in the Crooked River system. .......... 6-1

Plate 6-2. West Moberlys Fish Camp on the shores of the Crooked River, BC. ................................... 6-2

LIST OF APPENDICES

Appendix A. Raw Data from Biological Measurements of Fish from the Crooked River, September 2012

Appendix B. Raw Aging Analysis Results for Fish from the Crooked River, September 2012

Appendix C. Raw Tissue Metal Analysis Results for Fish from the Crooked River, September 2012

WEST MOBERLY FIRST NATIONS xiii

ABBREVIATIONS

Terminology used in this document is defined where it is first used. The following list will assist readers who may choose to review only portions of the document.

ATSDR Agency for Toxic Substances and Disease Registry

BC British Columbia

BC MOE British Columbia Ministry of Environment

BW Body weight

CCME Canadian Council of Ministers of the Environment

cm Centimeter

COPC Contaminant of potential concern

dw Dry weight

EDI Estimated daily intake

Fs Fraction of time eating fish

HHRA Human health risk assessment

HQ Hazard quotient

ICP-MS Inductively Coupled Plasma Mass Spectroscopy

IRIS Integrated Risk Information System

JECFA Joint Expert Committee on Food Additives and Contaminants

kg Kilograms

mg Milligrams

MLIB McLeod Lake Indian Band

mm Millimeter

MRL Minimal risk level

pTDI Provisional tolerable daily intake

QA/QC Quality Assurance/Quality Control

RfD Oral reference dose


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RMWI Recommended maximum weekly intake

Study Area Crooked River watershed in northeast British Columbia

TEK Traditional ecological knowledge

TDI Tolerable daily intake

TRV Toxicity reference value

UCLM Upper confidence limit of the mean

US EPA United States Environmental Protection Agency

West Moberly West Moberly First Nations

WHO World Health Organization

ww Wet weight

WEST MOBERLY FIRST NATIONS 1-1

1. INTRODUCTION AND APPROACH TO ASSESSMENT

1.1 OVERVIEW

Fish in the lakes, rivers, and creeks of Dunne-za hanan (the land of the Beaver people) are important to West Moberly First Nations (West Moberly) mode of life. Increased industrial activities in recent years, coupled with past developments, has become a serious concern for members of West Moberly with respect to the safety of using aquatic species that are traditionally harvested and gathered in accordance with the seasonal round. Many were particularly concerned about the extent to which the aquatic environment had been adversely impacted as a result of the construction of the W.A.C. Bennett hydroelectric dam that created the Williston Reservoir in northeast British Columbia (BC).

Based on the request of members to investigation the potential adverse health effects from mercury in fish harvested from the Aboriginal fisheries on the Crooked River, BC, West Moberly submitted a funding application to the Environmental Contaminants Program of the First Nations Health Authority, which was approved in 2014. This report provides the results of the study that was undertaken to determine the heath risks of consuming Bull Trout harvested in the Crooked River system in accordance with the traditional seasonal round.

1.2 STUDY AREA

The area selected for the study (Figure 1.2-1) has been identified as the Aboriginal fisheries in the Crooked River system in northeast British Columbia (the Study Area). Temporally, the Study Area has been a part of the land base that forms the seasonal round of West Moberly for a period that predates the arrival of Europeans in Dunne-za hanan and continues to this day. Past and present traditional land uses in the Study Area include hunting, fishing, trapping, and gathering activities, including, among other things, the traditions, customs, and practices that are incidental in nature (collectively, cultural activities). Many, if not all, cultural activities include a commercial component, such as the selling or trading of goods and services. West Moberly noted it is planning for such cultural activities to continue well into the future.

1.3 HUMAN HEALTH RISK ASSESSMENT FRAMEWORK

The assessment of risk to human health due to incidental ingestion of contaminants in fish is the main objective of this study. Human health risk assessment (HHRA) frameworks provide guidance on how to assess this type of risk. Federal HHRA guidance for screening level risk assessments was used in this assessment, including supplemental guidance specific to the assessment of risk due to consumption of country foods (Health Canada 2010c, 2010d, 2010a). Generally, HHRAs consist of five main components, which will be included in this assessment:

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Study Area for the Aboriginal Fisheriesin the Crooked River System

Proj # 0276885-0006 | GIS # CRF-15-002WEST MOBERLY FIRST NATIONS - Crooked River Fisheries

INTRODUCTION AND APPROACH TO ASSESSMENT


1. Problem Formulation

Problem formulation describes the conceptual model for conducting the risk assessment, setting the context for the scope of the assessment (i.e., what will be assessed). This includes identification of exposure route(s) and the food(s) being assessed, contaminants of potential concern (COPCs), and potential receptors.

2. Exposure Assessment

The exposure assessment stage of the HHRA determines the estimated exposure to COPCs. The exposure assessment takes into account any site-specific information that is available, or uses literature-derived data in the absence of site-specific data.

3. Toxicity Assessment

The tolerable daily intake (TDI) of a COPC is the amount of a contaminant that can be taken into the body without experiencing adverse effects. The TDI will be determined based on a search for TDIs defined by Health Canada, the United States Environmental Protection Agency (US EPA), the World Health Organization (WHO), the Agency for Toxic Substances and Disease Registry (ATSDR).

4. Risk Characterization

Both federal (Health Canada) and provincial (BC Ministry of Environment [BC MOE]) governments provide guidelines for fish tissue residues for mercury for the protection of human consumers. These guidelines will be considered in the risk characterization.

In addition, the exposure assessment and toxicity assessment are integrated so that the risk to human health is quantitatively described.

5. Uncertainties and Limitations

The assumptions made throughout the assessment are described, with consideration of how the assumptions affect the confidence in the assessment. Any limitations to the analysis are described.


2. PROBLEM FORMULATION

2.1 DATA USED TO SUPPORT THE RISK ASSESSMENT

2.1.1 Traditional Ecological Knowledge

Traditional ecological knowledge (TEK) of West Moberly includes, for example, information regarding species of fish, fish habitat, and fishing practices in the Crooked River system. An overview of the traditional seasonal round regarding which species of fish are targeted is illustrated in Figure 2.1-1.

In the spring each year, West Moberly sets up cultural camps (Fish Camps) to facilitate harvesting of fish, particularly Bull Trout (Salvelinus confluentus), in the Study Area. Based on the First Nations TEK, Bull Trout historically migrated from larger watercourses (e.g., Parsnip, Finlay, and Peace rivers) into smaller watercourses, such as the Crooked River. With the construction of the W.A.C. Bennett hydroelectric dam and the subsequent impoundment of water that flooded 1,700 km2 of land and considerable portions of the Parsnip and Finlay rivers and their tributaries, all of which formed the Williston Reservoir, TEK indicates that the species now migrates from the Williston Reservoir into the smaller watercourses. These fish are then caught during the Fish Camps within the Crooked River system.

The methods used to fish in the springtime vary to some extent. Bull Trout were previously harvested via nets and other traditional means, such as tree limbs and lines. Tissues from other species of fish were also used as an enticement technique (i.e., bait). Use of fishing poles is the primary technique that is currently used; this is not to say, however, that other methods are not used during the spring as well. Fresh tissue from other fish species is still used, specifically from the Peamouth (Mylocheilus caurinus), which is the preferred species to use as bait (see Plate 2.1-1). This is largely because Bull Trout have migrated into the Crooked River system to feed on the Peamouth, which spawns during the spring.

Fish are not randomly harvested (Plate 2.1-2 and 2.1-3). Selection of Bull Trout in the springtime varies depending on TEK and cultural requirements. As such, the amount of fish that are harvested and the sizes fluctuate from year to year. Fish are consumed on-site and off-site. Members from as far away as Vancouver, British Columbia, travel to the Fish Camps to participate in the cultural activities. In terms of the quantity of fish that is consumed at Fish Camp, West Moberly members noted that approximately 4 kg of fish is likely to be consumed by each adult per 3 days.

Most use one of two techniques when preparing a Bull Trout for consumption: (1) a fish is cleaned and smoked over an open fire, after which the dried pieces are placed into bags that are then distributed amongst family, friends, and potentially others (e.g., commercial activities); and (2) a fish is cleaned, cooked whole, and consumed during a meal by one or more people. Cooking techniques vary, as a fish may be pan fried along the side of the river whereas it is likely to be cooked on a barbeque or in an oven when individuals are at home. Some also bring the fish home for drying and smoking. All ages and both male and female members of West Moberly are likely to consume fish from the spring harvest. Filets of fish were not discussed as a means by which the fish are prepared and then consumed.


Fish and the Traditional Seasonal RoundFigure 2.1-1

Proj # 0276885-0006 | Graphics # MPF-0001-028g

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PROBLEM FORMULATION


Plate 2.1-1. Example of bait (i.e., Peamouth) used by West Moberly to catch Bull Trout on the Crooked River, BC.

Plate 2.1-2. Fish harvested via gill nets at culture camps in the Study Area during the summer months.


2-4 ERM | PROJ #0276885-0006 | REV C.1 | MARCH 2015

Plate 2.1-3. Example of Bull Trout harvested from the Crooked River, BC.

2.1.2 Fish Tissue Metals, Fish Age, and Other Biological Data

Fish were collected from the Study Area in May 2012 by members from McLeod Land Indian Band (MLIB) and West Moberly as part of cultural activities at that time. Of the numerous fish that were harvested in 2012 by each First Nation, a total of 57 Bull Trout (Salvelinus confluentus) and 3 Northern Pikeminnow (Ptychocheilus oregonensis) were submitted for testing by the participants. The largest reported Bull Trout was 22 lbs., which was caught by a member of MLIB; however, the member did not submit the fish or a portion of the fish for testing. The fish were frozen until they could be sampled in September 2012. Sampling of frozen fish was conducted on September 13 and 14, 2012. Frozen fish were measured for length and weight and then the heads and tails were removed from frozen fish using a reciprocating saw (Plate 2.1-4).The fish were repackaged and returned to a freezer, as participants requested that the fish be returned should the test results demonstrate that the fish were safe to consume.

A cross section from the caudal peduncle was removed and placed in an individually labelled Whirl-Pak bag. The tissue samples were immediately re-frozen and shipped to ALS Environmental in Burnaby for analysis of moisture content and metal concentrations. Fish heads were allowed to thaw overnight and then dissected to remove otoliths for aging analysis. Aging samples were sent to North-South Consultants in Winnipeg for analysis. Raw data from biological measurements are presented in Appendix A.

PROBLEM FORMULATION


Plate 2.1-4. Photo of fish sampling, including measurement of fish length and weight, September 2012

2.1.2.1 Analytical Testing

Aging Analysis

Otoliths were set in epoxy and left to cure for 48 hours. The nucleus was marked under a microscope and the otoliths were subsequently sectioned using a low speed sectioning saw, leaving the nucleus in the section. Finally otoliths were permanently mounted on a microscope slide. Ages were determined for all otoliths by one technician, while 10% of samples were randomly chosen for re-analysis by a separate technician to provide Quality Assurance/Quality Control (QA/QC) of the aging results. Raw aging data results are presented in Appendix B.

Tissue Metals Analysis

ALS Environmental analyzed the tissue samples for metals concentrations according to standard procedures adapted from the US EPA (1995, 1996, 2007). Samples were divided into two parts at the laboratory: one part for measurement of metal concentrations on a wet weight (ww) basis (in mg/kg ww) and a second part for measurement of percent moisture so that the results could be converted to mg/kg dry weight (mg/kg dw), if required.

Each sample was homogenized either mechanically or manually prior to digestion. The hotplate digestion method involved the use of nitric acid followed by repeated additions of hydrogen peroxide. Total concentrations of 24 metals were measured by Inductively Coupled Plasma Mass Spectroscopy (or ICP-MS). In addition, mercury was measured from each sample. Raw data, including detection limits, are presented in Appendix C. Laboratory-split duplicate QAIQC samples were conducted for



five samples. One of the five samples had a relative percent difference of 67%, which is higher than generally acceptable. This suggests that some samples may not have been fully homogenized.

2.2 SCOPE OF THE RISK ASSESSMENT CONCEPTUAL MODEL

For the purposes of the current assessment, the scope is limited to contaminant exposures from consumption of fish by humans. Other potential exposure routes for COPCs will not be included, and the health of fish populations is not considered.

The assessment will focus on Aboriginal consumers of fish from the Crooked River system, since available data suggests that Aboriginal peoples would have the highest consumption rates for fish in this area (Section 2.1; Health Canada 2010d). Traditional knowledge data collected during interviews with participants from West Moberly (described in Section 2.1.1) will be used in the Exposure Assessment (Section 3) to help define the level of exposure through fish consumption. It is acknowledged that other potential receptors may also consume fish from this system (e.g., other local residents, sport fishers, tourists), but these populations are not explicitly considered in the assessment.

The assessment will be based on tissue metal data from the fish that were caught in May 2012 in the Crooked River system (Figure 1.2-1). This included 57 Bull Trout and 3 Northern Pikeminnow, as described in Section 2.1.2. Due to the limited sample size for Northern Pikeminnow, which were collected and tested at the request of an Elder from MLIB, the assessment will predominantly be based on tissue metal data for Bull Trout.

The assessment will be limited to consideration of mercury in fish tissue. Data for fish tissue concentrations of metals other than mercury is provided in Appendix C, but is not considered in the risk assessment. Consideration of risk to human health due to the incidental consumption of these other metals in fish tissue can be evaluated at a later date (see Section 8.2 for recommendations).

2.2.1 Preliminary Estimate of Distribution of Bull Trout in the Study Area

Bull Trout are a highly migratory fish species, and may move long distances within a watershed. In order to provide a preliminary assessment of the potential distribution of Bull Trout within the study area (Figure 1.2-1), potential barriers to fish movement were identified. Fish barriers were identified only as waterfalls or velocity barriers; it is possible that there are additional barriers to fish movement that have not been included in Figure 2.2-1 (e.g., habitat limitations, water quality or quantity barriers).

Hagen and Decker (2011) noted that Bull Trout may be located in approximately 26 of the 36 Ecological Drainage Units that have been delineated in BC, which may include roughly 1,000 tributaries watersheds. As such, and based on a preliminary assessment of the potential fish barriers shown in Figure 2.2-1, it is possible that Bull Trout could have a fairly wide distribution with the ability to migrate between different sub-watersheds within the headwaters of the Peace River sub-basin, which ends at the site of the W.A.C. Bennett hydroelectric dam. Fish that were harvested from the Crooked River system may not necessarily be resident in this river and could move to and from the many different rivers, creeks, and lakes within the Upper Peace watershed (see, e.g., Figure 1 of Hagen and Decker, 2011).

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Date: April 08, 2015Projection: NAD 1983 BC Environment Albers

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Assumed Fish PresenceRestricted Fish PresenceHighwaySecondary RoadWilliston WatershedStudy Area

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WEST MOBERLY FIRST NATION

Contains information licensed under the OpenGovernment Licence British Columbia and Canada.Source: Esri, DigitalGlobe, GeoEye, EarthstarGeographics, CNES/Airbus DS, USDA, USGS, AEX,Getmapping, Aerogrid, IGN, IGP, swisstopo, and theGIS User Community

Potential Access Barriers for Bull Troutin the Williston Reservoir and its Tributaries


3. EXPOSURE ASSESSMENT

The objective of the exposure assessment is to determine the amount of exposure to mercury, which is dependent on human receptor (consumer) characteristics, as well as the concentration of mercury in fish tissue.

3.1 HUMAN RECEPTOR GROUPS

Based on TEK (Section 2.1.1), Aboriginal consumers of fish are expected to include people of all age groups and both genders (Plate 3.1-1). The risk to people from mercury present in fish tissue is known to vary with age of the consumer; children, pregnant women, and women of child-bearing age considered to be the most sensitive populations (see Section 4).

Plate 3.1-1. Youth at the Fish Camp on the shores of the Crooked River, BC.

Health Canada (2007) considers people over the age of 12 to have sensitivity for mercury similar to the general adult population. Therefore, the following age groups will be considered in the assessment:

toddlers, aged 1 to 4 years;

children, aged 5 to 12 years;

sensitive adult population; and

general adult population.



3.2 CONCENTRATION OF MERCURY IN FISH

Total mercury concentrations were measured in the fish tissue sent to ALS Environmental. Methylmercury is the form of mercury that is of greatest concern to human health (i.e., most toxic form of mercury to humans; Section 4). For fish, it is typically assumed that 100% of the total mercury concentration is in the form of methylmercury, although the proportion of methylmercury might be slightly less than 100% (Bloom 1992; Health Canada 2007). Since the actual concentrations of methylmercury are likely less than the total mercury concentration, this assumption ensures that the risk assessment is adequately conservative. Throughout the remainder of this report, the terms mercury and methylmercury will be used interchangeably.

The tissue samples of fish were collected from the caudal penduncle area (near the tail) of the fish. It is assumed for the purposes of the assessment that these tissue samples are representative of the concentrations of mercury throughout the body of the fish that could be consumed.

All fish, except for Fish #46, had detectable concentrations of mercury in tissue samples. For the purposes of calculations and statistics, the mercury concentration in Fish #46 was assumed to be equivalent to the method detection limit of 0.001 mg/kg ww. This is a conservative assumption since the lab analysis found that the concentration was less than the method detection limit.

3.2.1 Concentrations based on the Summary Statistics

Summary statistics for the concentration of mercury in Bull Trout and Northern Pikeminnow collected from the Crooked River system are shown in Table 3.2-1. Concentrations of mercury measured in each individual fish is shown in Figure 3.2-1, and a frequency distribution of the mercury tissue concentrations in Bull Trout is shown in Figure 3.2-2.

Table 3.2-1. Mercury Tissue Concentrations in Bull Trout and Northern Pikeminnow from the Crooked River system, May 2012

Concentration of Mercury (mg/kg ww)

Number of Fish Mean

Standard Deviation of

the Mean

95% Upper Confidence Limit

of the Mean Minimum 95th

Percentile Maximum Bull Trout 57 0.419 0.225 0.479


Mercury Tissue Concentrations (in mg/kg ww) Measured in Individual Bull Trout and Northern Pikeminnow, May 2012

Figure 3.2-1

Proj # 0276885-0006 | Graphics # MPF-0001-028f

123456789

101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657123

Sam

ple

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Concentration of Mercury in Fish Tissue (mg/kg ww)

Northern PikeminnowBull Trout

Note: ww = wet weight


Frequency Distribution of the Mercury Tissue Concentrations(in mg/kg ww) Measured in Bull Trout, May 2012

Figure 3.2-2

Proj # 0276885-0006 | Graphics # MPF-0001-028a

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Concentration of Mercury in Bull Trout Tissue (mg/kg ww)

EXPOSURE ASSESSMENT


Larger fish (i.e., those of increased length or weight) would be most desirable for harvesting, and these fish are associated with the highest concentrations of mercury (i.e., concentrations well above the mean concentration). Using a 95% UCLM to represent mercury concentrations in the whole population has the potential to underestimate the risk, particularly when eating fish that are older or bigger than the average. The same is true for using the mean concentration of mercury in fish.

In contrast, the 95th percentile of mercury concentrations in fish tissue represents the concentration for the majority of the population of fish (i.e., 95% of the fish would be expected to have a tissue concentration below this level). The maximum concentration is the highest concentration of mercury measured in any Bull Trout from 2012.

Risk calculations based on either the 95th percentile or the maximum concentration of mercury would be the most conservative compared to other statistics. Conversely, the use of the 95th percentile concentration in risk calculations has the potential to overestimate the risk for fish consumption as a whole. For example, if only smaller fish with lower mercury concentrations are consumed, the calculations based on the 95th percentile could significantly overestimate risk. The same is true for the use of the maximum mercury concentration in fish tissue.

However, an objective of this study is to evaluate risk in a way that ensures risk is not underestimated. Therefore, conservative assumptions should be used throughout the assessment. Therefore, for the purposes of determining risk, the 95th percentile of mercury concentrations in fish tissue is a reasonably conservative value that represents the upper end of mercury concentrations that were measured in Bull Trout from 2012.

3.2.2 Concentrations based on the Use of Regression Relationships

Regression analysis of the Bull Trout data found that there was a significant relationship between the age of the fish and mercury concentrations in tissue (Figure 3.2-3). The regression relationship between the age of fish and mercury concentration in tissue is: !"#$%#&'(&)"#"+,%'$-'.)#/)00-% = 20.06 78%9 0.03 [Equation 1] The Northern Pikeminnow that were sampled were older (26 and 30 years, one fish was not included in aging analysis) than the Bull Trout (average age of 7, n = 57). However, only three Northern Pikeminnow were sampled, which precludes the ability to compare trends in mercury accumulation between species of fish.

Although the regression relationship based on age was significant, age of fish is not something that can be determined easily in the field (i.e, aging of fish requires samples to be sent to the lab). Therefore, the regression relationships based age will not be discussed further in this assessment.

Significant correlations between mercury concentrations in tissue and length or weight (wet weight basis) were also found when analyzing the Bull Trout data using regression analysis (Figures 3.2-4 and 3.2-5). Concentrations of mercury in fish tissue increase with increasing length or weight. The regression relationship between the length (in millimeters, mm) and mercury concentration (in mg/kg ww) in Bull Trout tissue is:


Regression Relationship between Age (in years) andMercury Tissue Concentrations (in mg/kg ww) for Bull Trout

Figure 3.2-3

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Concentration of Mercury in Fish Tissue (mg/kg ww) = 0.06 (Age) - 0.03n = 57, adjusted r = 0.405, P < 0.001



Regression Relationship between Length (in mm) andMercury Tissue Concentrations (in mg/kg ww) for Bull Trout

Figure 3.2-4

Proj # 0276885-0006 | Graphics # MPF-0001-028c

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cent

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Concentration of Mercury in Fish Tissue (mg/kg ww) = 0.0015 (length) - 0.36

Note: ww = wet weightmm = millimeters


Regression Relationship between Weight (in kg) andMercury Tissue Concentrations (in mg/kg ww) for Bull Trout

Figure 3.2-5

Proj # 0276885-0006 | Graphics # MPF-0001-028d

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Concentration of Mercury in Fish Tissue (mg/kg ww) = 0.14 (weight) + 0.18

EXPOSURE ASSESSMENT


!"#$%#&'(&)"#"+,%'$-'.)#/)00-% = 20.0015 >%#8&)# 9 0.36 [Equation 2] The regression relationship between the weight (in kg) and mercury concentration (in mg/kg ww) in Bull Trout tissue is: !"#$%#&'(&)"#"+,%'$-'.)#/)00-% = 20.14 "%)8&)##89 + 0.18 [Equation 3] Although this makes the risk calculations more complicated, the use of the regression relationships provides the best estimate of the risk for consumption of fish of various lengths and weights. Consumers of the fish can get a better sense of the level of risk posed by fish of a particular size or weight, and could adjust their personal consumption rates of fish based on fish length or weight. This calculation goes beyond what is normally done in a preliminary quantitative risk assessment, since the calculations are more detailed and provide a less conservative (and potentially more accurate) estimate of risk.

3.3 ESTIMATED DAILY INTAKE

As part of a typical exposure assessment the estimated daily intake (EDI, in mg/kg bw/day) of mercury from fish is calculated. In addition to the concentration of mercury in fish tissue, the EDI is dependent on the ingestion rate of the consumer and the fraction of time in which fish is consumed.

To calculate the EDI of mercury, the following equation is used (Health Canada 2010a):

&'( = )*+,-./0.12 [Equation 4] where:

EDI = estimated daily intake of mercury from fish (mg mercury/kg bw/day) IR = ingestion rate of fish (kg fish/day) Cfood = concentration of mercury in fish (mg mercury/kg fish) FS = fraction of time eating fish (unitless) BW = body weight (kg bw)

Whenever possible, human receptor characteristics will be defined based on information collected during the interviews with participants from West Moberly (see Section 2.1.1). In the absence of specific or quantitative data, receptor characteristics recommended by Health Canada will be used (Richardson 1997; Health Canada 2007, 2010a).

The concentration of mercury to be used in the calculation of EDI is the 95th percentile measured in Bull Trout in 2012 (Table 3.3-1, or Section 3.2 and Table 3.2-1). This statistic was selected for the calculation of the EDI because the 95th percentile is a reasonably conservative measure of the upper end of the distribution of mercury tissue residues from Bull Trout sampled in 2012. This value is sufficiently conservative to be protective of human health, independent of fish size (weight or length).



Table 3.3-1. Values Used in the Calculation of Estimated Daily Intake

Parameter

Toddler (1-4 years) Children (5-12 years) Sensitive Adults General Population

During Fish

Camps Remainder

of Year

During Fish

Camps Remainder

of Year

During Fish

Camps Remainder

of Year

During Fish

Camps Remainder

of Year

Ingestion Rate 0.665 kg/day

0.082 kg/day

1.10 kg/day

0.136 kg/day

1.33 kg/day

0.132 kg/day

1.33 kg/day

0.163 kg/day

Mercury Concentration (95th Percentile)

0.796 mg/kg ww

Fraction of Time Eating Fish

1.0 0.14 1.0 0.14 1.0 0.14 1.0 0.14

Body Weight 14.4 kg 26.4 kg 60 kg 70.7 kg

The body weights used in the assessment are the ones recommended by Richardson (1997). For the sensitive adult population, the body weight is based on an adult woman of childbearing age. Body weights for each human receptor group are summarized in Table 3.3-1.

Because site-specific data is not available to guide the selection of appropriate consumption rates (Section 3.3.1) and frequencies (Section 3.3.2) for Aboriginal consumers engaged in traditional fishing activities, there is uncertainty in the calculation of an EDI. Assumptions based on the TEK data (Section 2.1.1) and available literature have been used to enable the calculation of an EDI. The EDI is then compared to the toxicity reference value (TRV) derived in the Toxicity Assessment (Section 4) to derive a hazard quotient (HQ) used for risk characterization (Section 5.3).

The values for use in Equation 4 to calculate the EDI are described in the following sections and are summarized in Table 3.3-1.

3.3.1 Serving or Portion Sizes

The ingestion rate of fish for Aboriginal consumers is difficult to estimate, given the traditional manner in which food is prepared and consumed (Plate 3.3-1). This is particularly the case when the spring harvest of Bull Trout is underway since a fish may be caught, prepared, cooked, and shared at the Fish Camps with multiple individuals, including visitors from other First Nations and non-aboriginals. Fish may also be canned, which would likely result in mercury concentrations similar to that of fresh fish (i.e., wet weight concentrations). Fish could also be dried, with randomly sized pieces placed into bags for consumption later in either the short-term or long-term. For the purposes of calculating an EDI, only the consumption of fresh fish was considered because no site-specific information was available and consumption rates for dried fish for relevant populations could not be found in literature.

Analysis of qualitative data collected as part of the interviews with West Moberly participants (Section 2.1.1) found that people do not think about fish consumption in terms of fillets or portion sizes, but rather in a cultural context (i.e., whole fresh fish and dried fish). Formalized collection of quantitative data for serving sizes of meals or daily consumption amounts was not done as part of

EXPOSURE ASSESSMENT


the interviews with participants from West Moberly engaged in traditional fishing activities at the Fish Camps or consuming fish at other times of the year (Section 2.1.1). However, it was estimated by participants that an adult could consume up to 4 kg of fish within a 3 day period while in attendance at the Fish Camps (Section 2.1.1); this equates to 1.33 kg/day for adults and this serving size was used in the calculation of the EDI.

Plate 3.3-1. Example of how traditional foods are provided at culture camps. Meats are prepared in different traditional ways throughout the day and evening for participants and visitors to eat when they are hungry.

Fish consumption during the remainder of the year was not estimated quantitatively so literature was consulted to define ingestion rates in kg/day. However, this contributes greater uncertainty to the calculations, and it is recommended that site-specific data be collected for use in a more detailed risk assessment.

Health Canada (2007) used a fish portion size of 0.150 kg for adults in their risk assessment for mercury in retail fish, and recommends the use of this portion size.

Richardson (1997) provides a mean fish consumption of 0.044 kg/day (individuals >12 years of age, both sexes) for First Nations in Canada, which was obtained from a Nutrition Canada Survey using a 24-hour consumption survey. Higher consumption rates were calculated for a fish-eater group (only 25% of the study participants reported eating fish in the previous day), which excluded the data from individuals that reported zero fish consumption. Amongst the fish-eater group, the consumption rates were: toddlers, 0.094 kg/day; children 0.165 kg/day; sensitive adults, 0.197 kg/day; and 0.217 kg/day for adult men (general population). However, this study did not distinguish between First Nations and Inuit populations and included participants from across Canada.



Chan et al. (2011) conducted a survey of Aboriginal peoples living on reserves in BC. One of the limitations of this study is that it focused on First Nations individuals living on reserves, who may not have the same consumption patterns as First Nations individuals living outside of the territory. This study found that the portion size for fish for adult women ranged from 0.087 to 0.132 kg and for adult men portion size ranged from 0.100 to 0.163 kg, which averages out to close to the value of 0.150 kg used by Health Canada (2007). Since the Chan et al. (2011) study is more recent, differentiates between male and female consumption rates, and is based on Aboriginal (on-reserve) fish consumers in British Columbia, the portion sizes at the upper end of the ranges for adult men and women were used in this assessment for the general population and sensitive adult population, respectively.

Based on the available data from TEK interviews (Section 2.1.1), it was assumed that toddlers and children consume fish at the same meals as adults. Since site-specific information is not available about portion sizes, a portion size adjustment based on proportions was used to determine fish consumption for these groups, using values recommended by Health Canada (2007). Toddlers, aged 1 to 4, are assumed to eat 50% of the general adult population portion size and children, aged 5 to 12, are assumed to eat 83% of the general adult population portion size. These proportions of portion size are conservative estimates (Health Canada 2007).

Therefore, daily consumption rates for toddlers are assumed to be 0.665 kg/day during the Fish Camp and 0.082 kg/day during the remainder of the year. For children up to 12 years old, daily consumption rates are assumed to be 1.10 kg/day during the Fish Camp and 0.136 kg/day during the remainder of the year. Ingestion rates used in the calculation of the EDI are also summarized in Table 3.3-1.

3.3.2 Patterns in Fish Consumption (Frequency of Consumption)

The consumption pattern for fish among Aboriginal peoples varies temporally and culturally. Individuals may consume large amounts of fish during the late spring-early summer seasons when the Fish Camps occur, which take place for up to one month. Consumption of fish depends on how long people stay at the Fish Camps . Bull Trout are often consumed multiples times in a day. That is, the fish are available (cooked and in one piece) throughout the day and evening for consumption during Fish Camps, as it enables members, and others (e.g., visitors), to consume fish whenever they are hungry.

During the summer season, fishing and consumption of freshly caught fish may still occur, but likely at a lower frequency than during the Fish Camps. Some of the fish caught during the fishing season (spring-summer) will be taken home and stored in the freezer for later consumption throughout the year (Plate 3.3-2).

Fish are may be frozen, canned, or dried in these cases. Although dried fish could be consumed during the Fish Camps and the remainder of the year, a consumption frequency for dried fish has yet to be determined. This is because the gathering of specific information would need to be planned well in advance in order to schedule data collection with seasonal practices; as such, calculating an EDI is not possible at this time (Section 3.3.1). It is recommended that receptor-specific information be collected about consumption rates and frequencies to enable a more accurate risk characterization in any subsequent assessment. However, it is acknowledged that consumption rates and patterns of traditional foods can vary both spatially and temporally, which can complicate a detailed quantitative HHRA.

EXPOSURE ASSESSMENT


Plate 3.3-2. West Moberly member with Bull Trout that were prepared for consumption at a later date.

For the purposes of the current assessment, the reported estimated consumption rate for adults of 4 kg in 3 days (Section 2.1.1). This was converted to a daily consumption rate (for adults) of 1.33 kg/day. It was assumed that people may consume fish at this rate on a daily basis throughout their attendance the Fish Camp; therefore, the fraction of time was set to be 1.0. This assumption could underestimate the risk if the portion sizes used in the calculation are too small. Conversely, risk could be overestimated if fish is eaten less often than daily or if the portion sizes used in the calculation are too large.

During the remainder of the year, it was assumed that only one portion of fish was consumed per week (i.e., a fraction of time of one day per week, or 0.14). This is likely to be an underestimate of the risk during the summer period when fresh fish can be caught and consumed right away. During the winter, one serving per week is likely more reasonable when considered as an average over the entire season.


4. TOXICITY ASSESSMENT

4.1 POTENTIAL EFFECTS ON HUMAN HEALTH DUE TO MERCURY

Once methylmercury is ingested, almost the entire amount is absorbed from the gastrointestinal track and distributed to all tissues in the body, where it has the ability to easily cross the blood-brain barrier and the placenta (Health Canada 2007). Human studies have found numerous adverse health effects after ingestion of methylmercury and the magnitude of the effects are dependent on the dose ingested and the duration of the exposure (Health Canada 2007). The primary target organs of methylmercury induced toxicity in humans are the central and peripheral nervous systems (Health Canada 2007). However, methylmercury can also produce toxic effects in the kidney, liver, and reproductive organs (WHO 2003).

When exposed to very high doses of methylmercury (either chronic or acute), the initial symptoms include (Health Canada 2007): paresthesia (pricking, tingling of the skin), malaise, blurred vision, concentric constriction of the visual field, deafness, dysarthria (difficulty articulating words), and ataxia (inability to coordinate voluntary muscular movements). Very high exposures can ultimately lead to coma and death (Health Canada 2007; National Institute for Minimata Disease 2014).

Observable toxicity symptoms may not occur with chronic exposure to low doses of methylmercury and it is possible that some foods and dietary habits can alter the possible effects from exposure (Chapman and Chan 2000; Health Canada 2004b). However; chronic exposure can have adverse effects on the immune system (Moszczynski 1997) and the cardiovascular system (Stern 2005; Virtanen et al. 2005).

There is an association between maternal methylmercury exposure and developmental effects in children (WHO 2003; Health Canada 2007). The most sensitive human sub-population to methylmercury exposure is the developing fetus, which can experience adverse neurological effects at much lower doses than adults do (Health Canada 2007). The primary adverse effects that are then observed in developing children include disruption in fine motor function, attention, verbal learning, and memory (Health Canada 2007). While these effects are not necessarily severe, the long-term consequences on the nervous system, such as cognition and learning are unknown (Health Canada 2007).

Because infants, children, and women of child-bearing age are particularly susceptible to the effects of methylmercury, specific tolerable daily/weekly intakes of methylmercury for these sensitive groups have been recommended by regulatory agencies such as Health Canada, the US EPA, and the World Health Organization Joint Expert Committee on Food Additives and Contaminants (JECFA; Health Canada 2007). However, the age at which the sensitivity to methylmercury in children is equivalent to that in the general population is not well understood, but the default recommended by the Bureau of Chemical Safety is 12 years of age (Health Canada 2007).



4.2 PROVISIONAL TOLERABLE DAILY INTAKE

The TDI of mercury is the amount of mercury that can be taken into the body on a chronic (long-term) basis without experiencing adverse effects. The term tolerable is used because it signifies permissibility rather than acceptability for the intake of contaminants avoidably associated with the consumption of otherwise wholesome and nutritious (country) foods (Herrman and Younes 1999). The TDI terminology is generally used by Health Canada, while other terms (such as oral reference dose, RfD) are used by other jurisdiction such as the US EPA.

There are different TDIs for inorganic mercury and methylmercury. Because the form of mercury expected to be present in fish tissue is methylmercury, TDIs for inorganic mercury were not considered. The following is a brief discussion about the TDIs from various agencies for methylmercury. The TDIs from the various agencies were all derived from long-term studies on human populations that consume fish year round.

For methylmercury, the US EPA Integrated Risk Information System (IRIS) provides an oral RfD of 0.0001 mg/kg bw/day (US EPA 2015). This RfD, derived in 2001, is based on human epidemiological studies in the Faroe Islands that looked at adverse effects of methylmercury on neuropsychological development, based on maternal exposure (via ingestion) during pregnancy. The RfD also incorporates an uncertainty factor of 10, which means that the methylmercury concentration associated with adverse effects has been divided by 10 in order to account for uncertainties in the studies.

The ATSDR developed a minimal risk level (MRL) for methylmercury of 0.0003 mg/kg bw/year (ATSDR 1999, 2014), also based on the measurement of developmental endpoints in children. This MRL was developed based on a different study (based in the Seychelles) than those used by the US EPA, and applied an uncertainty factor of 3 and a modifying factor of 1.5 (to account for results from the Faroe Island study).

JECFA recommends a provisional TDI (pTDI) of 0.00047 mg/kg bw/day for the general public, and 0.00023 mg/kg bw/day for sensitive groups (i.e., children and women who are pregnant or of child-bearing age; JECFA 2007). Use of the term provisional expresses the tentative nature of the toxicity evaluation, in view of the paucity of reliable data on the consequences of human exposure at levels approaching those indicated. When firm conclusions from robust scientific studies are able to be used in a toxicity evaluation, the provisional term is removed from the TDI. JECFA acknowledged that neurodevelopment is the most sensitive health outcome associated with methylmercury exposure, particularly for exposures of the fetus that occurs in pregnant women. The pTDI derived by JECFA considered both the Faroe Island and Seychelles studies, as well as available scientific literature. The pTDI incorporates as uncertainty factor of 6.4.

The JECFA pTDI was adopted by Health Canada (2010b), although for sensitive populations, a value of 0.0002 mg/kg bw/day was adopted.

The preference in this risk assessment is to use the Canadian pTDI, which has the benefit of distinguishing between sensitive populations and the general population. Provisional TDIs of 0.00047 mg/kg bw/day will be used for the general population and 0.0002 mg/kg bw/day for sensitive populations will be used in this assessment, consistent with values used by Health Canada (2007).

TOXICITY ASSESSMENT


4.3 ADJUSTMENT OF THE PROVISIONAL TOLERABLE DAILY INTAKE TO ACCOUNT FOR FISH CONSUMPTION PATTERNS BASED ON TRADITIONAL PRACTICES

In order to appropriately use the pTDI to assess risk to human health, it is important to take into consideration mercury exposure from other foods (e.g., background exposure to mercury due to consumption of retail foods) or exposure routes (e.g., inhalation, drinking water, etc.).

The primary source of mercury in the human diet is from fish or shellfish (Airey 1983; WHO 2003; Mahaffey, Clickner, and Bodurow 2004; Health Canada 2007; US EPA 2014). During the Fish Camps when fish may be consumed in high amounts, it is likely that the primary source of mercury in the diet is from the fish consumed while at the camps. It is unlikely that other fish or seafood is brought to the Fish Camps, or that other foods (e.g., dairy products, grains/breads, etc.) will contribute significant sources of mercury to the diet during this time.

Therefore, based on the consumption pattern described by attendees at the Fish Camp (Section 2.1.1), it is assumed that the RWMI based on mercury can be calculated assuming that all mercury exposure during this short period of time comes from consumption of the Bull Trout harvested at the Fish Camps. The pTDI used in the RMWI calculation will be the full amount of the pTDI, since it is assumed that 100% of an individuals mercury exposure during the Fish Camps comes from the Bull Trout. It is possible that the risk to human health due to mercury could be underestimated, since this assumption does not account for mercury intake through other foods or potential exposure routes.

At other times of the year (apart from the Fish Camp), it is possible that Aboriginal peoples may have exposure to mercury through other foods, including retail fish or seafood, or through other exposure routes (see, e.g., Plate 4.3-1 and 4.3-2). Typically in a screening level risk assessment, this background exposure is accounted for by decreasing the allowable risk by 80% (i.e., the exposure route or food being assessed contributes up to 20%, or one-fifth, of the total exposure). This assumption allows for the possibility that intake of mercury from background exposures could be significant, so there is a lower tolerance for intake of mercury from one specific food or pathway.

Therefore, the pTDIs used for mercury in fish tissue were divided by five during the rest of the year (outside of the Fish Camp). This ensures that the mercury intake from Bull Trout accounts for only one-fifth of the tolerable mercury intake, allowing for other background exposures not considered in this risk assessment. Thus, the pTDIs used for the RWMI calculation for periods of the year outside of the Fish Camp was 0.00004 mg/kg bw/day for sensitive populations and 0.000094 mg/kg bw/day for the general population. It is possible that the risk to human health is overestimated by making this assumption, since the amount of uptake of mercury through consumption of other foods or through other exposure pathways may make up less than 80% of the total exposure to mercury.



Plate 4.3-1. Bull Trout harvested in the fall season from the Carbon Creek, south of the Peace Reach of the Williston Reservoir.

Plate 4.3-2. Lake Trout harvested by West Moberly members.


5. RISK CHARACTERIZATION

In order to characterize the risk to human consumers of fish due to mercury content, multiple approaches will be used to ensure that risk is adequately identified and described.

The first approach to risk characterization is based on comparison of the measured mercury concentrations in fish to federal and provincial guidelines for mercury in fish tissue.

The second approach to risk characterization is calculation of a maximum recommended weekly intake (RMWI) of fish, based on the concentration of mercury measured in Bull Trout and the pTDI associated with minimal risk to human consumers. The RMWI will be calculated for two distinct periods of fish consumption patterns (i.e., fish consumption during Fish Camps and consumption during the remainder of the year). The RMWI will be qualitatively compared to the likely levels of fish consumption for Aboriginal consumers participating in the Fish Camps or consuming the fish throughout the remainder of the year in order to determine the likelihood of risk consumers.

The final approach to risk characterization is the calculation of HQs based on the EDI and the pTDI. However, due to the number of assumptions required to make these calculations, this approach is considered a preliminary risk estimate.

5.1 COMPARISON OF FISH TISSUE MERCURY CONCENTRATIONS TO TISSUE RESIDUE GUIDELINES

Tissue residue guidelines for the protection of human consumers of fish have been prepared by both the federal (i.e., Health Canada) and provincial (i.e., BC MOE) governments. As an initial estimate of the potential for risk to human consumers, measured fish tissue residues in Bull Trout and Northern Pikeminnow are compared to these guidelines.

5.1.1 Health Canada Maximum Contaminant Standard for Mercury in Fish Tissue

The Health Canada maximum contaminant standard for mercury in fish tissue is 0.5 mg/kg ww for most fish, except for a few species (escolar, orange roughy, marlin, tuna, shark, and swordfish) where the limit is 1 mg/kg ww (Health Canada 2012). It is noted that this standard applies to fish for retail sale, and as such, would not specifically apply to wild fish harvested by Aboriginal peoples. In addition, it is intended to protect against adverse effects due to mercury in the average fish consumer in Canada, which in many cases likely does not include subsistence consumers such as Aboriginal peoples. This guideline, therefore, will not be protective of consumers who eat more fish than the average consumer, particularly members of West Moberly.

Of the Bull Trout sampled in May 2012 from the Crooked River system, 37% had tissue residues of mercury that exceeded the maximum contaminant standard of 0.5 mg/kg ww. Of the three Northern Pikeminnow that were sampled in May 2012, all of them had concentrations of mercury greater than the standard.



There was a significant relationship noted between the concentration of mercury in fish tissue and the length and weight of Bull Trout. Based on the regression relationships defined in Section 3.2 (Equations 2 and 3), Table 5.1-1 shows the length and weight of Bull Trout that would begin to have tissue residues exceeding the maximum contaminant standard of 0.5 mg/kg ww.

Table 5.1-1. Length and Weight of Bull Trout Estimated to have Tissue Concentrations of Mercury Exceeding Health Canada Maximum Contaminant Standard

Health Canada Tissue Residue Guideline (mg/kg ww)

Length or Weight at which the Tissue Residue Guideline is likely to be Exceeded

Length (mm) Weight (kg)

Based on Regression Line

Based on Upper Confidence Limit

Based on Regression Line

Based on Upper Confidence Limit

0.5 573 550 2.3 2.1

Based on the linear regression, fish that are longer than 573 mm (57.3 cm), or heavier than 2.3 kg would be predicted to have mercury tissue concentrations exceeding the Health Canada maximum contaminant standard (Table 5.1-1). When considering the upper confidence bound of the regression line, fish that are 550 mm (55.0 cm) long or weigh 2.1 kg would be expected to have mercury tissue concentrations exceeding the Health Canada maximum contaminant standard.

5.1.2 BC Ministry of Environment Aquatic Life Guidelines for Mercury in Fish Tissue

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Aboriginal Health Risk Assessment of Mercury in Bull Trout Harvested from the Crooked River, British...

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