Quirks and Quarks

Sick legacy — how DDT exposure from the past can affect many generations to come

Study indicates that the granddaughters of women who were exposed are more likely to menstruate early, become obese and develop breast cancer

Animal studies suggest pollutant exposure may result in permanent changes to how genes work

Akilah Shahid (left) is one of 235 granddaughters from a multigeneration study that began with her grandmother, Beatrice Jett (right), back in the 1960s to track the effects of DDT in women. All are participants in the Public Health Institute’s Child Health and Development Studies research program. (Akilah Shahid)

New research is providing worrying evidence that your grandparents' exposure to toxic pollutants like DDT could increase the risk of illnesses for you and all your future offspring.

A recent study suggests that granddaughters of women who were exposed to DDT decades ago are more likely to menstruate early, more susceptible to becoming obese and may even have a higher risk of developing breast cancer.

Michele La Merrill, an environmental toxicologist from the University of California, Davis, is one of the authors of this multigenerational human study, but she also studies this in animals. 

She said that her group has also found in animals that DDT impedes how calories are burned, which leads to more calories getting stored as fat. 

Crews with the Greater Winnipeg Mosquito Abatement District use DDT to fog land and water in 1955. DDT was officially phased in Canada in the mid-1970s. (City of Winnipeg Archives/Parks and Recreation Photo Collection)

But other work suggests that the effects of pollution exposure could last well beyond three generations 

Michael Skinner, a biologist from Washington State University, studies how environmental toxicants, like DDT, affect epigenetic inheritance. That is the science of how changes to the way our DNA gets expressed can be transmitted to future generations.

He's found the effects of DDT exposure can be passed down four generations in rodents, but said based on other studies with different animals, and with different toxic chemicals, the effects could be expected to last many more generations, and may, in fact, be permanent.

Given the effects he and other scientists have seen, Skinner said our current and ancestral exposures — to DDT and many other toxic synthetic chemicals we've been exposed to over the years — could be behind the rise in chronic diseases around the world today.

Produced and written by Sonya Buyting. To hear the interview with Michael Skinner, click on the link at the top.