Agricultural pesticides and fine particulate matter air pollution were associated with geographical hotspots for pediatric inflammatory bowel disease (IBD) in the province, according to a study by BC Children’s Hospital researchers recently published in the World Journal of Gastroenterology.
These findings are important as Canada has one of the world’s highest rates of pediatric IBD.
“Last year, we diagnosed the highest number of kids we’ve ever diagnosed with IBD — 160 — outstripping population growth by a wide margin,” says pediatric gastroenterologist Dr. Kevan Jacobson.
“It’s crucial we understand why the incidence is increasing so we can prevent additional children from being afflicted with this debilitating disease.”
IBD comprises a group of chronic disorders that cause inflammation in the small or large intestine. The main forms of IBD are Crohn’s disease, which can cause inflammation in any part of the gastrointestinal tract, including the esophagus, stomach, and small and large intestines, and ulcerative colitis, which only affects the large intestine. Common symptoms of IBD include diarrhea, weight loss, fatigue and stomach pain. However, both diseases can also affect the skin, liver, joints and bones.
Researchers believe genetics and environmental factors interact to change an individual’s intestinal microbiome (the population of bacteria living in their gut) and increase their risk of developing IBD.
For this study, Mielle Michaux, a medical geographer with BC Children’s and the University of British Columbia (UBC) and Dr. Jacobson, director of the Pediatric IBD Program in the Division of Gastroenterology, Hepatology and Nutrition and the Department of Pediatrics at UBC, wanted to identify pediatric IBD clusters in the province and determine how these patterns were associated with population ethnicity and environmental exposures.
The researchers calculated the incidence of pediatric IBD for different areas of the province. They applied an ecological analysis that considered ethnicity, rurality, average family size and income, average population exposure to green space, air pollution, vitamin D levels and pesticide application.
Michaux and Dr. Jacobson were surprised that suburban areas turned out to be hot spots for IBD. Other Canadian studies have found the highest concentration of cases in their densest urban areas.
The Fraser Health area — from Burnaby to Fraser Canyon on the unceded territories of the Coast Salish and Nlaka’pamux Nations — had the greatest concentration of IBD cases, particularly ulcerative colitis. Other hot spots included the Southeastern Okanagan and Vancouver Island.
These results motivated the researchers to analyze areas of the province in relation to pesticide use.
“Population-level exposure to petroleum oil used on orchards and grapes was associated with an elevated risk of IBD in those areas,” Michaux says.
Exposure to greater amounts of fine particulate matter air pollution (PM2.5) was also found to be a contributing factor. Fine particulate matter is less than 2.5 micrometers in diameter. By comparison, a human hair is 70 micrometers. As these particles are very small, intake is great and the particles are able to penetrate deeply into the lungs.
“Consequently, one of the big environmental health threats to us in Canada and globally is PM2.5 pollution,” says Michaux.
The concentration of cases in the Fraser Valley is likely due to the high South Asian population. Being of South Asian descent was reconfirmed as a risk factor, an observation Dr. Jacobson made several years ago. Pesticide application and poor air quality may also be factors.
Protective factors included being of Indigenous descent, having a larger family and being exposed to ultraviolet rays from the sun to increase vitamin D.
The researchers aren’t quite ready to mete out specific advice on preventing IBD, but Michaux recommends paying attention to air quality advisories, using air filtration devices and wearing an N95 mask outside if air quality is poor, regardless of one’s health or age.
“Air quality is an important environmental health concern and will continue to be in the future,” she says.
“Children are especially susceptible to air pollution. Wildfire season is such a large threat to our health. This may be a sign that it’s not just cardiovascular disease or asthma we need to be thinking about. It’s some of the other chronic conditions.”
Dr. Jacobson recommends following a diet rich in whole grains, fruits and vegetables such as the Mediterranean diet. Fish and seafood should be consumed at least twice a week, but consumers need to be mindful of potential toxins when consuming excessive fish of the fatty varieties.
“We just have to be sensible,” he says. “How that relates to the environment, I don’t know that we fully know the answer to what being sensible actually means.
“Ultimately, one has to address inflammatory disease more holistically,” he continues. “This study is part of getting to the point where we can advise people on all of these environmental factors.”
Michaux notes ensuring access to safe green spaces, unpolluted air and sanitary water is key to improving health for everyone.
“Environmental health can be a great tool for equity, to make sure we all have access to clean, healthy, safe environments.”