Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Health Science

Faculty/School

Faculty of Science

First Advisor

Dr. Ketan Shankardass

Advisor Role

Supervisor

Second Advisor

Dr. Todd Coleman

Advisor Role

Thesis Committee

Third Advisor

Dr. Errol Thomson

Advisor Role

Thesis Committee

Abstract

Allostatic Load (AL) is a modifiable risk factor that impacts population health outcomes by conceptualizing the ‘wear and tear’ on the body from prolonged physiological and psychological stress. Low socioeconomic position, exposure to harmful environmental chemicals, and unhealthy lifestyles have all been linked to higher levels of AL, and these issues tend to affect racial minority groups more severely. Since there is very limited research on this issue in the Canadian context, this study examines racial disparities in allostatic load in the Canadian Health Measures Survey (CHMS); the role of environmental chemicals, socioeconomic position, and lifestyle factors as mediators of these disparities; and how these effects vary across age and sex groups.

The study used data from 6357 participants aged 20 and older from the Cycles 3 (2012-2013) and 4 (2014-2015) of the CHMS. Data were collected through household interviews and clinical measurements at mobile examination centers across the country. Data were analyzed using the SPSS version 31.0, the PROCESS Macro version 5, and SAS EG version 9 to estimate differences in coefficients between groups and to conduct mediation and moderated mediation analyses.

Compared to White participants, allostatic load was significantly higher among Black participants (β1 = 0.459, P < 0.001) and East/Southeast Asian participants (β2 = 0.159, P = 0.041); whereas it was lower among Middle Eastern participants (β4 = -0.411, P = 0.002). No significant differences were observed for Latin American participants (β5 = -0.074, P = 0.624) or South Asian participants (β3 = -0.072, SE = P = 0.478), adjusting for age and sex. The cumulative effect of socioeconomic position, healthy lifestyle factors, and cumulative chemical exposure increased the Black-White difference in ALI by about 14% and reduced the Middle Eastern-White difference by about 17%. Compared to White participants, allostatic load was more explained through socioeconomic position for Black participants (a1b=0.033, 95 %CI [0.0014, 0.0672]) but less explained through socioeconomic position for South Asian (a3b=-0.052, 95% CI [-0.083, -0.024]) or Middle Eastern (a4b=-0.032, 95 %CI [-0.066, -0.001]). The study found that across all racial groups, the indirect effects of socioeconomic position, healthy lifestyle factors, and cumulative chemical exposure on allostatic load did not vary by age or sex.

The study findings revealed substantial evidence of racial disparities in allostatic load and understanding of why they are happening in Canada. These findings demonstrate that, in this sample of the CHMS, socioeconomic position was the predominant factor driving racial disparities, with multifaceted statistical interactions suggesting that mediation by socioeconomic position was shaped by lifestyle factors and chemical exposure. Further study may require a chain of mediators and moderators for racial disparities in allostatic load. Addressing differences in socioeconomic position across racial groups in Canada may help reduce disparities in allostatic load and ultimately, chronic diseases, and improve health inequalities in Canada.

Convocation Year

2027

Convocation Season

Spring

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Available for download on Sunday, March 21, 2027

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