Regionally representative hair mercury levels in Canadian First Nations adults living on reserves

Analysis of chemical exposures in racial populations in Canada: An investigation based on the Canadian health measures survey

Despite demonstrated disparities in environmental chemical exposures by racial identity, no Canadian study has systematically assessed the feasibility of using a nationally representative dataset to examine differences in chemical concentrations by race. We assessed the feasibility and constraints of analysing chemical exposures in racial populations, including visible minorities and populations of Indigenous identity, using biomonitoring data collected through the Canadian Health Measures Survey (CHMS). Our primary objectives were to assess the ability to 1) generate geometric means and percentiles of chemical concentrations for racial populations by age or sex, 2) statistically compare concentrations among racial populations, and 3) calculate time trends of concentrations by race. We conducted these analyses for several priority chemicals: lead, cadmium, benzene, bisphenol A (BPA), and di(2-ethylhexyl) phthalate (DEHP). Survey participants self-identified as one of the following: White, Black, East and Southeast Asian, South Asian, Middle Eastern, Latin American, First Nations, Metis, and Inuit. Analyses were conducted for individual and combined cycles of the CHMS. Using data from the latest CHMS cycle in which each chemical was measured, we observed that sample sizes were sufficient to report geometric mean concentrations for all races except Inuit. Due to privacy considerations associated with small sample sizes, the 5th and 95th percentile concentrations could not be consistently reported for all racial populations in this analysis. While we were able to statistically compare concentrations among racial populations, the analysis was constrained by the limited number of statistical degrees of freedom available in a single CHMS cycle. Both of these constraints were alleviated by combining multiple cycles of data. The analysis of time trends was less subject to privacy and statistical limitations; we were able to calculate time trends of chemical concentrations for all racial populations. Our findings provide an important baseline for follow-up investigations of descriptive and etiological analyses of environmental chemical exposures and race in the CHMS.

The evolution of symptoms of nervous system dysfunction in a First Nation community with a history of mercury exposure: a longitudinal study

BACKGROUND

Since the 1960's, mercury (Hg) contamination of the aquatic environment of Asubpeeschoseewagong Anishinabek (Grassy Narrows First Nation) territories has impacted the community members' traditions, culture, livelihood, diet and health. Despite decreasing Hg exposure over time, a recent study suggested that long-term exposure contributed to later-life symptom clusters of nervous system dysfunction. Here, the objective was to evaluate, 5 years later, the prevalence and progression of these symptoms and examine the contribution of long-term, past Hg exposure.

METHODS

The symptom questionnaire, applied in the 2016/17 Grassy Narrows Community Health Assessment (GN-CHA) (Time 1), was re-administered in the 2021/22 Niibin study (Time 2). A total of 85 adults (median age: 47y; range: 29-75y) responded at both times. Paired statistics were used to test the differences (Time 2 - Time 1) in self-reported symptom frequencies. The symptom clustering algorithm, derived from the entire study group of the GN-CHA (n = 391), which had yielded 6 clusters, was applied at Time 1 and 2. Equivalent hair Hg measurements (HHg) between 1970 and 1997 were used in Longitudinal Mixed Effects Models (LMEM), with a sub-group with ≥ 10 repeated HHg mesurements (age > 40y), to examine its associations with symptom cluster scores and their progression.

RESULTS

For most symptoms, paired analyses (Time 2 - Time 1) showed a significant increase in persons reporting " very often" or "all the time", and in the mean Likert scores for younger and older participants (< and ≥ 50y). The increase in cluster scores was not associated with age or sex, except for sensory impairment where a greater increase in symptom frequency was observed for younger persons. LMEM showed that, for the sub-group, long-term past Hg exposure was associated with most cluster scores at both times, and importantly, for all clusters, with their rate of increase over time (Time 2 - Time 1).

CONCLUSIONS

The persistence of reported symptoms and their increase in frequency over the short 5-year period underline the need for adequate health care services. Results of the sub-group of persons > 40y, whose HHg reflects exposure over the 28-year sampling period, suggest that there may be a progressive impact of Hg on nervous system dysfunction.

Levels of metals and persistent organic pollutants in traditional foods consumed by First Nations living on-reserve in Canada

Objectives

First Nations may have a higher risk of contaminant exposure from the consumption of traditional foods. The objective of this study was to measure concentrations of metals and organochlorines in traditional foods commonly consumed by First Nations in Canada and estimate the risk from dietary exposure.

Methods

Data were collected from the participatory First Nations Food, Nutrition and Environment Study (2008–2018). Traditional food samples were collected by community members and concentrations of metals and organochlorines were measured. The population-weighted mean daily contaminant intake from traditional food items was estimated. Hazard quotients (HQs) were calculated by dividing contaminant intake with the toxicological reference values (TRVs).

Results

A total of 2061 food samples (different parts and organs) from 221 species were collected. The highest concentrations of cadmium were found in the kidneys of land mammals: moose kidney was the most significant contributor to intake. The meat of land mammals and birds had the highest lead concentrations and were the most significant contributors to intake. Arsenic was highest in seaweed, and prawn was the most significant contributor. Mercury and methyl mercury were highest in harp seal meat, with walleye/pickerel contributing most to intake. Harp seal meat also had the highest p,p′-DDE and PCB concentrations, and ooligan grease and salmon were the most significant contributors to intake. The percentage of adults eating traditional food who exceeded the TRVs was 1.9% for cadmium, 3.7% for lead, 13.6% for arsenic, 0.7% for mercury, and 0% for p,p′-DDE and PCBs. All median HQs, and most 95th percentile HQs, were less than 1.

Conclusion

These results can be used as a baseline of contaminant levels and exposure in traditional foods for future monitoring programs and to support risk assessment programs.

Supplementary Information

The online version contains supplementary material available at 10.17269/s41997-021-00495-7.

The relationship between dietary exposure to persistent organic pollutants from fish consumption and type 2 diabetes among First Nations in Canada

OBJECTIVE

We previously examined the associations between dietary dichlorodiphenyldichloroethylene (DDE) and polychlorinated biphenyls (PCBs) intake from fish consumption and type 2 diabetes (T2D) prevalence in Ontario and Manitoba. This study aims to further explore the relationship in a regionally representative sample of First Nations adults living on-reserve across Canada.

METHODS

Dietary, health and lifestyle data collected by the cross-sectional First Nations Food, Nutrition and Environment Study (2008-2018) were analyzed. This participatory study included 6091 First Nations adult participants who answered questions on T2D. The consumption of locally caught fish was estimated with a food frequency questionnaire. A total of 551 samples from 96 fish species were collected and analyzed for the presence of DDE and PCBs. The associations between fish and dietary DDE/PCBs intake with self-reported T2D were investigated using multiple logistic regression models adjusted for confounders.

RESULTS

Dietary exposure to DDE (>2.11 ng/kg/bw) and PCBs (>1.47 ng/kg/bw) vs no exposure was positively associated with T2D with ORs of 2.33 (95% CI: 1.24-4.35) for DDE and 1.43 (95% CI: 1.01-3.59) for PCBs. The associations were stronger among females (DDE OR = 3.11 (1.41-6.88); PCBs OR = 1.76 (1.10-3.65)) and older individuals (DDE OR = 2.64 (1.12-6.20); PCBs OR = 1.44 (1.01-3.91)) as compared with males and younger participants. Also, significant dose-response relationships were found for fish consumption in females only.

CONCLUSION

This study confirms our previous findings that dietary DDE/PCBs exposure may increase the risk of T2D. The effect of DDE/PCBs from fish consumption is driven by geographical differences in DDE/PCBs concentrations in fish and by the amount of fish consumed, and is more prominent in females than in males.

The First Nations Food, Nutrition and Environment Study (2008-2018)-rationale, design, methods and lessons learned

OBJECTIVE

To describe the rationale, the participatory nature of the methodology, and the lessons learned during the First Nations Food, Nutrition and Environment Study (FNFNES), a community-based participatory research project implemented in eight Assembly of First Nations regions, which includes the entirety of Canada south of the 60th parallel.

METHODS

FNFNES respected the First Nations principles of Ownership, Control, Access and Possession (OCAP®) ( https://fnigc.ca/ocap ). A random sampling strategy based on an ecosystem framework comprising 11 ecozones was adopted to collect representative nutritional and environmental health results for all First Nations adults living on-reserve south of the 60th parallel. Data collection occurred during the fall months from 2008 to 2016. Respective First Nations were involved in the planning and implementation of data collection for the five principal components: household interviews, tap water sampling for metals, surface water sampling for pharmaceuticals, hair sampling for mercury, and traditional food sampling for contaminants.

RESULTS

A total of 6487 adults from 92 First Nations participated in the Study (participation rate 78%). A higher percentage of females (66%) participated than males (34%). The average age of males and females was similar (44 and 45 years, respectively). This study offers a novel body of coherent and regionally representative evidence on the human dimension of the ongoing environmental degradation affecting First Nations.

CONCLUSION

FNFNES serves as a good example of participatory research. We encourage public health professionals to develop policy and programs building on the participatory dimension of the research as well as on its results. The information collected by the FNFNES is also important for community empowerment, environmental stewardship and the general promotion of good health by and for First Nations peoples in Canada.

Can scientists and knowledge keepers sit comfortably together? An Indigenous physician's reflections on a decade of participatory research into First Nations nutrition, environment and health

The author, an Indigenous physician, offers his reflections on the history of scientific research with Indigenous People and its past role in ethical breaches and excesses of colonialism, as a backdrop to the relatively recent advances in collaborative, community-based participatory research involving First Nations and Inuit in Canada. The First Nations Food, Nutrition and Environment Study (2008-2018), introduced in this Special Issue, is presented as an example of an ethical space that was sustained for a decade to collaboratively develop new knowledge by First Nations and scientists working together, respectfully and inspired by shared interest. A short overview of twelve articles of the Special Issue is provided and characterized as creating a previously inaccessible picture of the modern diets of First Nations, along with the suite of environmental factors that are present in food and water in and around communities. Ultimately, the author hopes that Canadian society can set the table with Indigenous Peoples and respectfully set opinions onto each other and do this over and over again. With Canada already being a multicultural and pluralistic society, adding Indigenous realities into the mix only respects and honours the Indigenous roots of this country.