Presented by: Mohammadali Saffarzadeh BSc
Department of Urologic Sciences, University of British Columbia

Introduction

Elevated ambient temperature is a known risk factor for development of kidney stones that can be affected by seasonal changes or by heat stress especially in indoor spaces. Other understudied exposures including heavy metals have also been associated with increased incidence of nephrolithiasis. We assessed the distribution of known kidney stone risk factors including occupational heat stress; occupational cadmium, lead, and arsenic exposures; and elevated ambient temperature secondary to seasonal variations across Canadian regions. This may aid in establishing targeted resource planning and risk mitigation strategies.

Materials

Data on the number of working Canadians employed in occupations with heat and heavy metals exposures was obtained from Statistic Canada from the year 2021. Number of Canadians working in these high-risk industries were mapped across Canada to create easily interpretable risk maps. Regional daily temperatures of all Environment Canada recording stations in 2021 was averaged over the hottest 3 months of the year to determine the warmest provinces/territories in the year. Significance of the results was evaluated based on 95% confidence interval difference from the null hypothesis.

Results

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Warmest summers were experienced in provinces in lower latitudes, with the hottest summers being recorded in Ontario (Fig. 1A). Most regions had similar rates of occupational heat stress ranging from 619-865 people per 10,000 working age Canadians except for Nunavut at a lower rate of 375 per 10,000 (Fig. 1B). Data on the combined occupational cadmium, lead, and arsenic exposures indicated significantly higher exposure rates in Yukon and Northwest territories with non-overlapping 95% confidence intervals compared to the remaining Canadians regions (Fig. 1C).

Conclusion

An ambient-temperature-based approach to preventative counselling merits consideration given the looming climate crisis. Occupational exposures to cadmium, lead, and arsenic were higher in Northern Canada, suggesting the potential benefit in risk reduction strategies through safe work practices in these areas. Due to multiple confounders, direct causation of stone occurrence from these exposures cannot be measured; however, distribution of these risk factors has implications for resource allocations as none of the Canadian territories have access to permanently stationed urologists.

Funding

No funding was received for this project.

Co-Authors

Alec Mitchell, MD
Department of Urologic Sciences, University of British Columbia

Connor Forbes, MD, FRCSC
Department of Urologic Sciences, University of British Columbia