Common pesticide could be feeding obesity rates

Chlorpyrifos is banned in Canada, but is likely present on fruits and vegetables imported into the country.

Dave Yasvinski 3 minute read August 30, 2021
chlorpyrifos pesticide obesity

Chlorpyrifos is banned in Canada, but it's likely already on fruits and vegetables we eat here. GETTY

A pesticide banned in Canada but widely used in other parts of the world may be contributing to the global obesity epidemic, according to a new study that recommends eating local and washing produce properly before preparing dinner.

The study, published in the journal Nature Communications, found that chlorpyrifos — a chemical sprayed on fruits and vegetables to keep bugs at bay — slows down the calorie-cutting ability of the brown adipose tissue of mice. Impeding this process, better known as diet-induced thermogenesis, increases obesity as the body is forced to store extra calories.

“Brown fat is the metabolic furnace in our body, burning calories, unlike normal fat that is used to store them,” said Gregory Steinberg, senior author of the study and professor and co-director of the Centre for Metabolism, Obesity, and Diabetes Research at McMaster University in Hamilton, Ont. “This generates heat and prevents calories from being deposited on our bodies as normal white fat.”

Obesity is a progressive, chronic disease that is a leading cause of type 2 diabetes, high blood pressure, heart disease, stroke, arthritis, cancer and other serious health problems, according to Obesity Canada. The prevalence of the disease has increased significantly over the past few decades to the point that more than one in three Canadians has a level of obesity that may require medical assistance to manage. It is believed that one in 10 premature deaths in adults between the ages of 20 and 64 can be directly attributed to obesity.

The team of scientists stumbled upon the concerning consequences of chlorpyrifos by examining the effects of 34 different pesticides and herbicides on brown fat cells and then specifically testing how chlorpyrifos impacts mice on high calorie diets. They found a little goes a long way when it comes to this particular pesticide, concluding that the chemical concoction can add an extra five pounds to waistlines every year if it inhibits energy use in brown fat by just 40 calories per day.

“We know brown fat is activated during cold and when we eat,” Steinberg said. “Lifestyle changes around diet and exercise rarely lead to sustained weight loss. We think part of the problem may be this intrinsic dialling back of the metabolic furnace by chlorpyrifos.”

Chlorpyrifos is not permitted for use in Canada, but Steinberg cautioned it is likely already present on fruits and vegetables imported into the country. “Although the findings have yet to be confirmed in humans, an important consideration is that, whenever possible, consume fruits and vegetables from local Canadian sources and if consuming imported produce, make sure it is thoroughly washed,” he said.

Previous studies have found that humans have a disturbing number of chemicals circulating through their bodies, including 42 that researchers can’t even identify. The 109 chemicals most recently documented — included 55 never before seen in humans — have also been found in the bodies of newborn babies, likely arriving there through the placenta during pregnancy.

“These chemicals have probably been in people for quite some time, but our technology is now helping us to identify more of them,” said Tracey J. Woodruff, a professor of obstetrics, gynecology and reproductive sciences at the University of California, San Francisco.

“It is alarming that we keep seeing certain chemicals travel from pregnant women to their children, which means these chemicals can be with us for generations.”

Dave Yasvinski is a writer with