Using Urine Arsenic Concentrations as Biomarkers for Environmental Exposure Among Children and Youth in Yellowknife, Canada

Abstract

Arsenic (As) a naturally occurring metalloid, is widely distributed in the Earth's crust and groundwater. While As exist naturally in soil, sediments, and groundwater, Giant Mine's previous operations have left a legacy of As, lead, and cadmium pollution throughout the geographic landscape of the city of Yellowknife. Children's and youth's As exposure is of particular concern due to its known carcinogenic effects on human health. The objective of this thesis is to quantify Yellowknife's children and youth urinary As, lead and cadmium levels, determine the relationship between urine metal concentrations and Kidney Injury Molecule-1 biomarker and investigate the potential environmental and/or demographic factors that determined their exposure. Urine samples from 369 children aged 3 to 19 were collected in 2023 and compared to the rest of the Canadian population. The results show that geometric mean urine total As, inorganic As and lead concentrations of Yellowknife children and youth were higher than the Canadian mean, but all were below the 95th percentile. Also, urine total As, cadmium, and lead concentrations in Yellowknife children's urine have increased since 2017-18, while urine inorganic As concentration has decreased. KIM-1 expression increased with age, but it was not statistically associated with urine As concentrations. Participants' urine inorganic As levels were associated with As concentrations in soil samples collected from areas corresponding to 53 postal codes. Spatial analysis identified twelve geographic hotspots across Yellowknife, including three areas with an elevated inadvertent rate of inorganic As ingestion. The results emphasize that Yellowknife exposure patterns have changed since 2017-18, there are limitations to KIM-1's use as a biomarker and high exposure groups are geographically clustering, likely due to higher levels in the local soil.