Why Do So Many Canadian Kids Have Bowel Inflammation?

Is it pollution and pesticides? Does ethnicity play a role? New research looks into Canada's high rate of pediatric inflammatory bowel disease.


It should not come as a surprise that pollutants in our environment can have harmful health effects. In recent years, we’ve seen cases of certain pesticides being potentially linked to cancer, air pollution being responsible for millions of premature deaths, and microplastics being found in the human bloodstream.

Yet a new study from researchers at the University of British Columbia and British Columbia Children’s Hospital may shed some light on the role of environmental pollutants on one of the more perplexing families of diseases: pediatric inflammatory bowel disease (IBD).

According to the authors, previous research in Norway, France, Finland, and Manitoba has found geographical clusters, or hotspots, of IBD cases — which have been linked to environmental factors — but none so far have examined these hotspots in relation to pediatric IBD cases. Canada itself has one of the highest rates of pediatric IBD in the world, making it a suitable candidate for further research.

The authors focused their search in British Columbia, and hypothesized that they would be able to locate pediatric IBD hotspots and coldspots and link them to both demographic and environmental factors.

A total of 1,183 patients were selected using a registry of patients diagnosed with or receiving care for IBD at BC Children’s Hospital between the years of 2001 to 2016 and under the age of 16.9. These included diagnoses of Crohn’s disease (CD), ulcerative colitis (UC), and inflammatory bowel disease-unclassified. Other variables collected included ethnicity, family size, average family income, and geographic variables matched to the postal codes of patients such as levels of vegetation, greenness, vitamin D UV, nitrogen dioxide, ozone, fine particulate matter, and pesticides.

The researchers were able to identify a statistically significant cluster distribution of pediatric IBD cases. Particular BC hotspots included the lower mainland (IBD, CD, UC), the Okanagan (IBD, CD) and Vancouver Island (CD). Areas with particularly lower cases, or coldspots, included southeastern BC (IBD, CD, UC), Northern BC (IBD, CD), and the BC coast (UC).

Various protective factors that were associated with lower rates of pediatric IBD were also discovered. These included Indigenous ethnicity, larger family size, summer UV radiation, and metam pesticides. For example, the authors found that “a 1% increase in the Indigenous population of a [local health area] was associated with a 4.4% decrease in the number of IBD cases […] while a 20% increase in Indigenous population was associated with a 59% decrease in IBD.”

On the other hand, various risk factors for pediatric IBD were also found. These included South Asian ethnicity, increased greenness, increased air pollution, and petroleum oil pesticide use. For example, “each 1 μg/m3 concentration increase in […] air pollution was associated with a 29.4% increase in IBD cases.”

The authors reiterate the paper’s novel findings associating environmental factors with pediatric IBD cases, particularly air pollution and agricultural pesticides. As one of the researchers summarized in a press release, “ultimately, one has to address inflammatory disease more holistically… [T]his study is part of getting to the point where we can advise people on all of these environmental factors.”

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Borna Atrchian is an MA student in the Department of Political Science at the University of Toronto. Having previously completed a Behavioural Neuroscience degree, he is passionate about issues where politics and power intersect with psychology and human behaviour. He is interested in understanding the conditions that create distrust of the scientific community, as well as finding the most effective ways to rebuild this trust.