Could your great-grandmother’s pesticide exposure be the reason you’re overweight today?
According to a new study, exposure to the synthetic insecticide DDT could set off a genetic chain reaction causing one’s grandchildren, great-grandchildren and generations beyond to become obese.
“What your great-grandmother was exposed to during pregnancy, like DDT, may promote a dramatic increase in your susceptibility to obesity, and you will pass this on to your grandchildren in the absence of any continued exposures,” said Michael Skinner, the Washington State University scientist behind the research, which was published this week in the journal BMC Medicine.
While investigating how DDT exposure might affect inheritance in general, Skinner and his team exposed pregnant rats to the insecticide, which was developed in the 1940s to combat insect-borne diseases like malaria and typhus, but banned in the United States in 1972 due to mounting public health and environmental concerns.
They found that while the exposed “parent” rats and their children didn’t express an increased obesity risk, more than half of the third–generation rats — the “grandchildren” — developed the disease.
Skinner’s lab has also demonstrated the ill effects of other chemical compounds, including plastics, pesticides, fungicides, dioxins, hydrocarbons and bisphenol-A, or BPA. These toxins have been shown to disrupt the molecular processes of DNA, causing certain genes to turn “on” or “off” without changing their sequence.
The DDT results have only been demonstrated in gestating rats, but the researchers believe similar effects could be seen in humans. DDT has now been banned in the United States for more than 30 years, but “the third generation of people exposed in the 1950s is now of adult age and has a dramatic increase in diseases such as obesity,” Skinner said in a statement.
It’s worth noting that the study concluded that ancestral DDT exposure may be a factor in the current obesity crisis, but it’s not the whole story. As tempting as it may be to blame grandma, lifestyle choices like diet, activity and stress level have also been shown to play a part in weight gain.