Human Health

1.1      Introduction

1.1.1    Purpose of the Blueprint

This Blueprint outlines the research issues and questions to be addressed by the Human Health subprogram of the Northern Contaminants Program (NCP) so that Northerners can assess, understand and better manage the health risks in Northern Canada related to the long-range transport of contaminants and their presence in people and traditional/country foods. This is closely aligned with the goals of Inuit and First Nations organizations that have a shared objective to improve health and wellness among their populations across the Arctic.    

The scope of the Blueprint provides a continuing opportunity for Northern health authorities and/or First Nations and Inuit governments to take the lead on projects within their own regions, enabling Northerners to control and increase their own research capacity more directly. The Blueprint identifies priorities and activities in the areas of human biomonitoring, health effects and benefit/risk evaluation.

The funding envelope for Human Health projects in the 2017-2018 fiscal year is set at $1,025,000.00. 

1.2      Background

Elevated concentrations of polychlorinated biphenyls (PCBs), various organochlorine pesticides and metals such as mercury and lead have been found in human tissue samples and body fluids in certain Arctic regions. Epidemiological and toxicological studies in Canada and elsewhere have found that at certain concentrations these contaminants are toxic to humans.

The most recent assessment of contaminants and Human Health in the Canadian Arctic (published in 2009) provided some key conclusions and identified a number of knowledge gaps resulting from research supported by the NCP as well as externally funded research.  Some of the key conclusions from the report that are still relevant today are listed below:

  • Many contaminants measured in maternal blood over a period of about 10 years experienced significant declines in all Canadian Arctic regions studied (NWT, Nunavut and Nunavik).
  • Data indicate that co-exposure to a mixture of chemicals appears to modify not only some tissue contaminant levels but also the toxicity of at least some contaminants such as methylmercury and PCBs.
  • Prenatal exposure to contaminants in the Arctic may result in poorer immune system function and distinct but subtle effects on neurodevelopment  in children
  • The current dietary transition in some parts of the Canadian Arctic from traditional/country foods to a market-based diet has led to decreases in intake levels of key nutrients, omega-3 fatty acids and fibre. This transition can contribute to an increased risk of various chronic diseases in First Nations and Inuit communities.  
  • Most successful risk communication processes draw on and involve a variety of regional experts as well as the public in the formal communication process.

1.3       Biomonitoring for Human Health

One of the knowledge gaps identified in the most recent contaminants and Health Assessment Report (2009) was that biomonitoring as well as food choice surveys and monitoring of traditional/country foods should be continued to provide a clearer understanding of how a changing diet affects contaminant concentrations in Northerners. This work should continue to focus on a cross-section of highly and moderately exposed regions and should include both legacy and emerging contaminants of potential concern where there is the potential for exposure from traditional/country foods.

The assessment of contaminant concentrations in traditional/country foods along with food choices and dietary surveys will be essential to assess sources and levels of dietary exposure. These elements of the biomonitoring program should be developed such that future assessments will be carried out with the cooperation and/or collaboration of project leads responsible for biotic monitoring under the Environmental Monitoring and Research subprogram. This provides an excellent opportunity for collaboration between Human Health and Environmental Monitoring and Research project leads in the North and would be particularly beneficial for regional health and environmental authorities and/or First Nations and Inuit governments evaluating these projects. In particular, Northern health authorities may be interested in having studies under the Human Health and Environmental Monitoring and Research subprograms co-located. Doing so will strengthen the links between the two subprograms and ensure that knowledge gained on contaminants in the ecosystem is transferred to the assessment of human health risks. The results generated through such cooperation will also allow for further assessment of spatial and temporal trends.

In order to place human chemical concentrations in a health risk assessment context, there is a need for tools to interpret biomonitoring data.  For example, there are only a few substances for which direct relationships between human chemical concentrations and health effects have been established.  For lead and mercury, intervention guidelines were established on the basis of studies that directly related blood levels with health effects. Biomonitoring Equivalents (BEs) can be used as tools to help interpret biomonitoring data in a health risk context.  Biomonitoring Equivalents are defined as estimates of chemical concentrations in human samples consistent with existing exposure guidance values that have been developed in Canada and elsewhere.  BE values for dioxins, hexachlorobenzene, cadmium and DDT have been published previously.  BEs are principally intended as screening values applicable  at the population level that can help determine which biomarkers are present at concentrations below, near, or above existing exposure guidance values. The unique exposure of northern populations to legacy POPs and metals suggest BEs may serve as useful tools for northern health professionals during their prioritisation efforts for risk management activities.  Other tools for interpreting northern biomonitoring data will also be considered. 

Prospective biomonitoring programs should be designed to build on pre-existing biomonitoring data and provide for periodic re-sampling (approximately 4 to 6 year sampling period).   By focusing on continuation of pre-existing datasets in a comprehensive and recurrent manner, a robust biomonitoring program will be established to create comparable datasets and allow for planned continuity, resulting in more meaningful trend analyses covering all regions of Canada’s Arctic.

Work under the biomonitoring program for Human Health falls under two main categories: dietary exposure assessments and human biomonitoring.

 

1.3.1     Dietary exposure assessments

The purpose of conducting dietary exposure assessments is to provide an up-to-date estimate of the amount (i.e. mass) of contaminants in the diet of Northerners and to determine likely exposure scenarios. These estimates of dietary exposure can then be compared with guidelines for safe levels of contaminant intake (i.e., tolerable daily intake (TDI)). Dietary exposure assessments were carried out in most regions of the Canadian Arctic at some point over the past 10 years and in many regions these data now require updating. The updated assessments, when compared with past assessments, will provide valuable information on changes in contaminant concentrations in traditional/country foods, changes in dietary habits, and ultimately on changes in exposure to dietary contaminants.

To complete dietary exposure assessments there is a need to conduct new food choice and dietary surveys. The survey data will indicate which traditional/country foods should be given the highest priority for monitoring of contaminants. Food choice surveys will also provide information about the factors affecting the dietary choices of Northerners and the perception of contaminants in making those choices. A number of dietary surveys have been undertaken by NCP researchers over the last 15 years in Yukon, NWT, Nunavut and Nunavik. This has provided valuable information for the interpretation of human contaminant biomonitoring and wildlife monitoring data and has allowed the development of better risk management advice to Northerners.

In connection with these surveys, samples of traditional/country foods should also be collected to allow the measurement of contaminant concentrations, including some of the contaminants of concern listed in Schedule A and Schedule B. Measurement of contaminant concentrations in traditional/country foods should be carried out in cooperation with project leaders from the Environmental Monitoring and Research subprogram, who can provide existing data on concentrations and trends in key food species and who also have expertise in analyzing emerging contaminants of concern.

The assessment of contaminant exposure needs to be coupled with an assessment of nutrient intake, which is essential for evaluating dietary risks and benefits.

In priority regions for human biomonitoring, described in Section 1.3.2, dietary exposure assessments, particularly the food choice and dietary surveys, should be carried out in parallel with the human biomonitoring studies. This will allow valuable comparisons of dietary exposure assessments to measured contaminant concentrations in human tissues and will facilitate the development of effective dietary intervention strategies.

The NCP has supported several maternal contaminant studies (Nunavik, Baffin and Inuvik regions) and various phases of the IPY-Inuit Health Survey (2007–2008) in Nunavik, Nunatsiavut, Nunavut, and the NWT to study both contaminant concentrations in human tissues and dietary exposure to contaminants. This body burden and dietary exposure information still requires detailed evaluation and will allow development of better intervention strategies. The evaluation results will also be used to inform international/national regulatory organizations dealing with contaminants (such as the Stockholm Convention) as well as future dietary/human biomonitoring studies.

1.3.2    Human biomonitoring

Biomonitoring studies that have measured POPs and metals in maternal blood over the past two decades suggest declines for certain POPs and metals in the Canadian Arctic (NWT, Nunavut, and Nunavik) amongst different population groups including Inuit, Dene/Metis, and non-Aboriginal northerners.  These biomonitoring studies have informed where and how human exposures to contaminants are changing and have also allowed an assessment of the effectiveness of international agreements.

The coincident collection of information on dietary choice and food frequency during  biomonitoring studies will permit researchers to further elucidate contaminant exposures from country foods and better understand modern dietary transitions in the North.

Role of Northern Health Authorities and First Nations and Inuit Governments

Any region in Canada’s Arctic can be considered for human biomonitoring studies if the Northern health authorities and/or First Nations and Inuit governments are engaged and have an interest in participating in the biomonitoring work.

It is important that the Northern health authorities and First Nations and Inuit governments are involved in the development of these human biomonitoring projects. Understanding that there are many demands placed on their limited resources, Northern Health Authorities can gauge their level of involvement based on internal capacity and interest.  Their participation aligns with the desire of Northerners to conduct their own research in the North and allows project leaders to more easily encourage community engagement in the projects. Having the Northern health authorities involved in the biomonitoring component will ensure that any important health, dietary or contaminant issues that may arise will be addressed for the communities in the most appropriate health context. Including First Nations and Inuit governments will ensure the cultural context of issues will be considered before publication/dissemination of results.

The objective of NCP human biomonitoring is to provide as complete coverage of each northern region as possible to fill regional gaps in data and develop time trends to allow on-going insight on the changing relationship between contaminant exposures and human health outcomes.  Ultimately, these studies, in conjunction with monitoring results from the Environmental Monitoring and Research subprogram, will help the NCP to determine the effectiveness of international agreements such as the Stockholm Convention and the Minamata Convention.  In addition, data from these biomonitoring studies using this standardized approach can be used to inform local health authorities of the general health status of northern populations from a contaminants perspective.

The overarching goal of NCP human biomonitoring is to create time trends and fill regional gaps; however this does not preclude the NCP from adjusting the schedule to address targeted biomonitoring if the need arises.  For example a rapid dietary shift in country food consumption or increased levels of contaminants in country food species regularly monitored through the Environmental Monitoring and Research subprogram would be valid reasons for establishing a biomonitoring program in the affected region.

Funding Parameters

A biomonitoring project will usually extend from three to five years and include the following key elements: regional consultation and engagement, project design/feasibility assessment, project implementation/execution, and reporting of results to the communities. The planning process should not be underestimated and usually requires at least one year to prepare a comprehensive proposal.  The proposals should set the general requirements for the project, including recruitment strategy, sample size and frequency (a position paper on these components was prepared by Health Canada), dietary assessment, collection of demographic information through questionnaires, contaminants to be measured, laboratory capacity, data analysis, and reporting of results.  The participation and collaboration of the Northern health authorities and First Nations and Inuit governments/organizations will ensure that regional communications on contaminants will be balanced and incorporated into ongoing health messages.

Seed Funding

In order for biomonitoring studies to commence in regions not currently part of long term NCP funded biomonitoring work, interested parties may apply to the Call for Proposals for seed funding to establish partnerships with regional health authorities, First Nations and Inuit governments or organizations, academia/federal scientists and local community organisations.  Seed funding may be used to support travel and facilitate meetings in northern communities with all of these key potential partners.  Seed funding may also be used for preparatory work on research design, survey development or other pertinent prelimi nary work.  Seed funding will be of a limited amount and will be scaled according to the scope of the proposed biomonitoring work.  In addition, seed funding will be provided for one year only.  Applicants who receive seed funding are not guaranteed to receive long term funding for future biomonitoring work and must submit proposals for each subsequent year of funding applied for.

1.3.3    Target populations for human biomonitoring

The NCP has identified key target populations for human biomonitoring.  Early biomonitoring studies focussed on pregnant women in order to obtain information on potential health impacts for the unborn child, recent studies have included both genders and all adult age groups to obtain a better understanding of human exposures across the Canadian Arctic.  Therefore the priority populations for biomonitoring studies under the NCP are presented as follows in order of importance:

  1. Pregnant women and women of child-bearing age.
  2. Children
  3. Adults of both genders and in particular older adults

Pregnant women and women of child-bearing age are the highest priority due to the sensitivity of the developing fetus to contaminant exposure.  Maternal trends that are not confounded by the sampling medium or differing study design can be determined through the continued sampling of maternal blood using prior protocols.  Children are the next priority for biomonitoring studies as they have been found to have relatively high concentrations of some contaminants (e.g., polybrominated diphenyl ethers (PBDEs)). Research of this type will highlight the interest of First Nations and Inuit governments and Northern health authorities in supporting this mother/child unit.  Biomonitoring of older adult populations of both genders is important because contaminant concentrations have, in general, been shown to be higher in this adult population than in children and pregnant women or women of child bearing age due in part to higher historical and current consumption of country foods.

1.3.4    Contaminants of concern

The chemicals of interest for the core biomonitoring program have been prioritized into two general groups: legacy contaminants and additional/emerging contaminants. Effort should be made to coordinate the biomonitoring of these chemicals of interest under the Human Health subprogram with those monitored within the Environmental Monitoring and Research subprogram.

Broadening the spectrum of monitored contaminants to include chemicals studied in Canada under the Chemicals Management Plan (CMP), supports public health efforts by territorial, provincial, and federal risk management groups to take action on chemicals found to be harmful to people and their environment.

Priority 1: Legacy contaminants

The core biomonitoring program would continue to measure legacy contaminants (POPs and heavy metals including mercury, lead, cadmium and selenium) in human tissue and traditional/country foods to ensure comparability with earlier datasets to be used in trend assessments and to fulfill Canada’s commitment to monitoring these contaminants under international agreements. Northerners continue to be exposed to legacy contaminants through the consumption of traditional/country foods.  See Schedule A for a list of legacy POPs for continued monitoring. 

Priority 2: New and emerging contaminants

Monitoring by the NCP also includes new and emerging contaminants that need assessment and monitoring to determine if they are present in the Arctic environment and in human tissues given their persistent and bioaccumulative properties and their ability to be transported long distances into the Arctic. It is expected that a number of chemicals measured under the CMP will meet these criteria and thus should be monitored under the NCP.

Schedule B contains a list of additional/emerging contaminants that are known to fall within the NCP’s mandate. Several new contaminants have already been included or nominated as potential candidates for regulation under UNEP’s Stockholm Convention and the UNECE 1998 Aarhus Protocol on Persistent Organic Pollutants (POPs).

Other Relevant contaminants and nutrients

The biomonitoring program  may include chemicals that Northern populations are exposed to through local use and exposure (e.g., store-bought foods, the preparation and preservation of traditional/country foods, drinking water and consumer products) to fully understand the exposure profile of Northern populations. However, applicants are expected to seek alternate funding sources for these analyses. See Table 6.1.

However, selenium should continue to be measured as part of NCP funded Health Research. Biomonitoring studies should include other contaminants/nutrients that are relevant to understanding potential health effects associated with consuming traditional/country foods.

1.4      Human Health Effects Research

The focus of the health effects element is the study of the interactions and effects of contaminants on human biological systems through investigations based on measurable determinants of health. The desired outcome is to reduce the current burden of environmentally-related disease, and to minimize environmental health risk across all life stages by addressing single and multiple chemical exposures. Investigative techniques could include epidemiological, laboratory-based toxicological and relevant toxicogenomic studies.

1.4.1    Health Effects Priorities

The following outlines the priority themes for health effects studies under the NCP:

  • Child and maternal health effects including pregnancy complications, endocrine disruption, duration of gestation and fetal growth;
  • Physical, motor, cognitive, behavioural, and emotional development from infancy to childhood, adolescence ,and adulthood;
  • Research into interactions between nutrients and contaminants (e.g., methyl mercury and selenium), particularly in the area of lifestyle, nutritional status and contaminant-related health effects;
  • Diabetes, metabolic syndrome, and cardiovascular disease;
  • Subclinical effects observed as DNA damage, enzymatic activity variations and other measured changes in studied human biomarkers;
  • Other chronic diseases likely to be associated with early-life or multi-exposure scenarios (such as allergy and asthma); and
  • Immune system function, especially mild immune system malfunction leading to increased risk of infections.

Health effects studies should take into account co-exposure to mixture of chemicals and factors likely to modulate vulnerability of exposed individuals.  Special interest should be devoted to characteristics of the diet of First Nations and Inuit groups where evidence exists for potential protective strategies such as specific micronutrient intake (e.g., selenium, polyunsaturated fatty acids, vitamins, and antioxidants). For example, interactions between methyl mercury and selenium should be investigated, as well as whether health effects are resulting from high concentrations of contaminants (e.g., selenosis from high selenium concentrations).

It is expected that results from current and previous biomonitoring studies such as the Inuit Health Survey and the Nunavik Child Development Study will be used to guide future pathways and effects research. The following sections provide further guidance on pathways and effects research priorities for the NCP.

1.4.2    Pathways

Biomarkers

Biomarkers have the potential to provide an early detection system for health conditions that may develop later in life or can help address epidemiological issues that cannot be investigated directly because of low sample numbers. Research that focuses on biomarker development, however, is beyond the scope of the NCP. Any work with biomarkers funded through the NCP should be integrated within an epidemiological (or toxicological) study and should demonstrate that a gap in NCP work will be filled by the research. Convincing arguments need to be made by project applicants regarding the relevance of these biomarker studies to the Arctic human context.  In order for a project to be considered for funding, the chosen biomarkers should demonstrate a link to clinical health effects or health outcomes currently or potentially afflicting Arctic peoples. Similarly, a relationship needs to be established between such health effects and contaminants

Human Genomics

Human genomics has received much attention in recent years and has been raised as a potentially beneficial area of research related to the effects of contaminants. Identifying the molecular mechanisms behind the contaminant effects observed in Arctic peoples could be a useful approach to clarifying how contaminants affect the human body. Genomics has the ability to identify the molecular mechanisms associated with certain chemically related exposures at a very early stage and possibly uncover new biomarkers of toxicity. Any NCP-funded genomic work should emphasize applied outcomes relevant to the Arctic human situation and will need to be clearly linked to known biomarkers of contaminant toxicity and/or to the elucidation of the mechanisms of action for high priority Northern contaminants. Proposed projects must use existing, well-validated genomic methods.  Projects must ensure relevant and specific informed consent and ethical approvals regarding the use of samples for genomic analysis and that First Nations and Inuit community or individual approval processes have clearly been obtained.  

1.4.3    Health effects and relevance to Arctic populations 

Contaminants have been associated with reproductive and developmental effects in studies of Southerners and people exposed to contaminants occupationally; similar effects have been found in laboratory studies using animals. Reproductive concerns among Canadian Northerners have not emerged at a clinical or epidemiological level and fertility rates among Northern Aboriginal people are among the highest in Canada. Despite this, reproductive studies will be considered by the NCP if a clear rationale is provided showing that reproductive effects related to contaminants are, or may become, a concern in the North.

The population is exposed to a mixture of contaminants rather than individual chemicals. During the past few years, NCP toxicological studies have investigated not only the health effects of individual contaminants but also the effects of mixtures that mimic the exposure profile of highly exposed Northerners. Early results demonstrate that the effects of the mixtures are not necessarily the same as those expected from studies of the effects of individual chemicals and that interactions occur among contaminants.

Arctic epidemiological research is revealing that nutrients found in certain traditional/country marine foods may offer some partial protection from the detrimental health effects of contaminants found in those same foods. Lifestyle factors may also influence the health effects of contaminants. For example, smoking during pregnancy is common in Northern communities. In such cases, a host of other chemical contaminants may contribute to (or mitigate) the effects of prenatal exposure to Arctic contaminant mixtures.

There are a number of factors that come into play to ensure that studies of effects funded by the NCP are relevant in the Arctic human context. Researchers are required to provide a brief but strong rationale justifying their choices with respect to each of the points below and especially their relevance in the Arctic human context:

  • The mixtures of contaminants and nutrients to be used should typify those found in traditional/country food diets or (human) maternal/cord blood, as appropriate.
  • While mixture studies are a priority, studies of the effects of individual contaminants will be considered if a strong rationale is provided.
  • If the study is in-vitro or based on laboratory animals, the specific exposures, including nutrients, should take into consideration the actual range of exposure levels (e.g., frequency distributions of exposure) experienced by Arctic residents.
  • Residual tissue concentrations of contaminants in laboratory animals should be measured to assess whether they are consistent with those of exposed Arctic human populations.
  • Study endpoints need to be able to be interpreted in an Arctic human context (e.g., appropriate neurobehavioural and sensory endpoints).

1.5      Benefit/Risk Evaluation

The ability to determine and compare benefits and risks is a key component of the NCP and a current focus of the Human Health subprogram. Standard risk assessment methodologies used to assess the potential risks to human health of various contaminants are, in general, well known and have been used for many years. However, their application to populations dependent on the use of traditional/country foods can be problematic because there is little consideration given to benefits, and there are no common metrics to compare multiple risk/benefit scenarios. For example, reporting that some consumers of traditional/country foods are exposed to concentrations of a particular contaminant above the TDI should be considered only a preliminary stage of assessing the overall risk because it does not account for the many health benefits that can be attributed to the consumption of traditional/country foods.

The development of methodologies for assessing the benefits of traditional/country foods is a relatively new area of research, and some of the benefits are only described in subjective terms. These benefits pertain to overall well-being and can be nutritional, physical, social, spiritual and economic, whereas the risks focus on the narrower questions of toxicity and potential health effects. It is, therefore, very difficult to evaluate the benefits against the risks, or vice versa, and considerably more research is required in this area.

When developing management strategies to balance the benefits of the traditional/country food diet and the risks from contaminants in that diet, it is also crucial to look at the benefits and risks of dietary alternatives (e.g., a typical (affordable) store-bought diet). Because the benefits and risks associated with store-bought foods are very different from those associated with traditional/country foods, and many of the benefits of the latter would be irretrievably lost by switching to store-bought foods, both techniques to “balance” the benefits and risks of store-bought foods with the traditional/country food diet and the development of management strategies that consider the complete diet require attention.

Arctic communities face risks from a variety of sources: contaminant exposure is only one. It is important to these communities that the risks and benefits associated with exposure to contaminants in traditional/country foods are placed in a context relevant to the community in question. Issues surrounding food security and malnutrition are of increasing concern in Arctic communities and could have profound effects on health, particularly in early life. Communities also require more information on how the risks from contaminants compare with other lifestyle risks such as smoking, alcohol consumption and other substance use. It is well known that these other lifestyle factors pose considerable risk to the developing fetus.

Projects that intend to study the evaluation of benefits and risks should focus on those communities considered to be at higher risk, as determined in consultation with public health authorities, from contaminants (e.g., communities characterized by high and moderate exposure to contaminants and dependent on a primarily marine mammal diet). Because the fetus, infants and children are often most at risk from contaminants, benefit/risk evaluations and communication should focus on their particular situations. This may require special communication efforts to pregnant women and women of child-bearing age.

1.5.1    Benefit/risk evaluation priorities

The following are the priority areas of NCP Human Health research on benefit/risk evaluations:

  • Improve our understanding of the factors influencing Northerners’ choice of food and the extent to which contaminants factor into these choices, with particular emphasis on mothers, pregnant women and other women of child-bearing age.
  • Evaluate food substitution and other management programs that aim to reduce contaminant exposure in high risk regions but still encourage consumption of highly valued traditional/country foods and other nutritional food sources.
  • Carry out benefit/risk evaluations and comparisons with special emphasis on the most highly exposed communities and vulnerable groups (e.g., the fetus, infants and children).
Table 1. Other contaminants of potential interest but outside of the NCP mandate.
Chemicals aJustification

Exposure from consumer products

(e.g., phthalates, bisphenol A)

Exposure from food

  • Pesticides
    (e.g., organophosphates, pyrethroids)
  • Metals
    (e.g., total arsenic, speciated arsenic, cobalt, zinc)
  • Other
    (e.g., polyaromatic hydrocarbons [PAHs])

To fully understand the exposure profile of populations in the Arctic, it is important to have information on chemicals that populations are being exposed to through imported foods and other routes of exposure.

The main route of exposure for these chemicals is thought to be through dietary consumption or through consumer products.

In addition to food exposure, consumer products may pose a risk of exposure to other chemicals such as phthalates and bisphenol A.

Other biomarkers of exposure

(Cotinine)

High concentrations of cadmium have been linked to smoking in the Arctic. Measuring cotinine, a biomarker for exposure to cigarettes, would clarify the issue of smoking in the Arctic.

aMeasured in human urine samples


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