Researchers Find DDT Dangers Span Three Generations, Grandchildren at Risk of Disease

DDT being sprayed on Prince of Wales Island, Southeast Alaska, 1963. Image: USDA/Flickr

by Amy Lupica, ODP Staff Writer

Decades after scientists first discovered the dangerous public health risks of the pesticide DDT, researchers have confirmed that two generations later, it’s impacting the grandchildren of women exposed in the 1950s and 60s.

  • Those exposed to DDT before it was banned first-hand saw increased rates of breast cancer; subsequently, their children experienced higher rates of obesity, birth defects, reduced fertility, and testicular cancer in sons.
  • Now, scientists at UC Davis and the Public Health Institute in Oakland say DDT has leaped one more generation.

Why This Matters: 
Silent Spring, released in 1962 by Rachel Carson, originally documented DDT’s harm to ecosystems. The pesticide, designed to kill many species of insects at once, permeated the water and land, leading to defects, infertility, and death in hundreds of species. That the chemical still impacts the grandchildren of human victims implies that hundreds of species and habitats may be suffering similar generational consequences and that the battle against DDT is far from over.

As we begin Earth Week, it’s a reminder that the fight for our planet is ongoing and just as necessary today as it was when Rachel Carson began raising awareness about the dangers of chemicals through her research

Dangerous DDT: This is something that people had always thought was possible,” said Barbara Cohn, director of the Public Health Institute’s Child Health and Development Studies, “but there had never been a human study to support the existence of that link.” The latest study found that a grandmother’s exposure to DDT could put granddaughters at a higher risk of obesity and early menstrual onset, increasing the risk of breast cancer, high blood pressure, diabetes, and other diseases. The results come from a longitudinal study that has followed more than 15,000 pregnant women and their descendants since 1959.


One unique element of these studies is that the consequences of DDT use 50 years ago are still coming out generation by generation. Each pregnant woman in the survey provided samples to evaluate the presence of DDT, but until their children are at a certain age, it can be challenging to say for sure if they, too, have been affected. These new findings come from the evaluation of women now in their 20s and 30s. “Even though we banned that stuff more than 40 years ago, people now walking the Earth — the granddaughters of those who were pregnant — were exposed,” said Cohn. She says that the public health community should take this as a cautionary tale and not wait for longitudinal results before deciding to practice restraint.


“Forever Chemicals”

It’s the full meaning of what a ‘forever chemical’ is — in some ways, that makes every chemical potentially ‘forever’ if it has the potential to do this,” said Cohn. Julia Brody, executive director at the Silent Spring Institute, agrees, “we don’t want to wait the next three generations to find out the chemicals that are in use now cause breast cancer.”

One way to hunt down which chemicals may have generational impacts on humans is to evaluate smaller animals with shorter life cycles. Researchers hope that by identifying endocrine disruptors in other species, they can determine what chemicals contribute to early menstrual periods, obesity, cancer, and more.

Researchers hope that many future generations will choose to participate in the study, and for many descendants, the findings bring answers and closure. Akilah Shahid, 30, said that knowing her family was a part of the study made things click. “How many times have we talked about climate change and things that we need to do better for our children and grandchildren? This is more proof that hello, what we do today is going to affect people way forward,” she said. “I hope this is a wake-up call for a lot of people because we’re talking about saving the environment again, today, for our future generations.”


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