New research published in Nature Communications has found that a common pesticide can promote obesity slowing down the ability to burn calories of some fat cells. Animal study indicates Chlorpyrifos, banned in Europe in January 2020 and still used in the US (to be banned from next year) suppresses thermogenesis in brown fat.
After years of lengthy court battles, the US Environmental Protection Agency (EPA) recently announced a ban on the agricultural uses of Chlorpyrifos. It will be in effect in 2022, just a year from now. But it comes 20 years after residential uses of the chemical were banned. The causes? Many, starting with the growing evidence of impaired neurological development in children.
Chlorpyrifos does not make the body react to burn calories from food
This latest study began by examining the effects of several dozen common pesticides and herbicides on brown fat cells in mice. Gregory Steinberg, senior author, states that brown fat is activated to burn calories when we eat and when we are cold.
“Brown fat is our body's metabolic furnace, burning calories, unlike regular fat which is used to store them,” says Steinberg. “This generates heat and prevents calories from being deposited on our bodies as normal white fat.”
The main discovery of the new study, published in the journal Nature Communications, was that Chlorpyrifos suppresses the calorie-burning functions of brown fat in mice. This has exacerbated the development of insulin resistance and obesity in animals.
There's more to calorie thermogenesis
However, the most novel part of the research is another. It involves exploring these metabolic outcomes in relation to the temperature of the environment in which the animals were housed. Generally, mice are housed under standard human room temperature conditions of 21-23 ° C (69-73 ° F). Researchers say this actually puts the mice under a small degree of cold stress. This can elevate the basic metabolic rate of the animals. And it can mask any impact of diet-induced calorie thermogenesis.
Previous studies in rodents have found a link between Chlorpyrifos and obesity when animals are exposed to levels of the chemical that generally mimic real-life toxicity levels in humans (around 2,0 mg/kg body weight). This new research validated those previous findings, but found that even much lower concentrations of the chemical cause metabolic disruptions when mice are housed in warmer conditions.
Effects on humans? Totally similar
Steinberg is wary of noting that these new findings have not yet been replicated in humans. But he points out that the differences in calorie burning effects from brown fat would be minimal. Simply stopping burning 40 calories a day in brown fat could result in nearly 2,3kg (5lbs) of weight gain per year in humans.
