DDT Exposure Quadruples Breast Cancer Risk

Written by Melissa Breyer

I find it surprising when people find it surprising that pesticides can have a harmful effect on human health. These chemicals are designed to kill living organisms – and yes a bug is tiny compared to a human, but after repeated exposure? Common sense might dictate that this is not a healthy thing.

But even so, a new study published in The Journal of Clinical Endocrinology & Metabolism is … surprising. Or not? Who can even tell any more. But one thing is for sure, it’s distressing.

Researchers looked at 54 years of data on women starting from the time they were in utero; 9,300 of them, all daughters of women who were part of a study at the Kaiser Foundation Health Plan from 1959 to 1967 in California. Although DDT was banned in the United States in 1972, during the time of the initial study the pesticide was widely used and it accumulated in the food supply. It was also imbued in consumer products, like wallpaper. Oh dear.

Joe Wolf/Flickr/CC BY 2.0

Among the mothers in the study, all of them had a measurable level of DDT in their blood. The researchers figured out the level of daughters’ exposure to DDT in utero by analyzing stored blood samples that were taken from the mothers during pregnancy or shortly after they delivered their babies, explains The Washington Post. They then collected data on the daughters, who are now in their late 40s and early 50s, to determine breast cancer rates.

What they found was that the daughters of mothers with elevated levels of DDT in their blood were four times as likely to have breast cancer, independent of the mother’s history of breast cancer. They also concluded the daughters of mothers with higher levels of exposure were diagnosed with more advanced breast cancer.

The study shows “direct evidence” that higher DDT exposure in utero places women at increased risk of breast cancer, said study author Barbara Cohn, PhD, a researcher at the Public Health Institute in Berkeley, California.

“Environmental chemicals have long been suspected causes of breast cancer, but until now, there have been few human studies to support this idea,” she said.

Even though DDT, one of the first known endocrine disruptors, has been banned for 43 years, its legacy endures – many women who may have been affected are just now getting to the age when they are at a higher risk for breast cancer.

And despite the fact that DDT has been associated with other ill-health effects as well, like Alzheimer’s disease, obesity, and kidney and ovarian diseases, a number of countries still use it in the war against malaria. The authors of the study hope that policymakers will consider their research as they decide on banning or continuing the use of DDT.

This post originally appeared on TreeHugger

Photo credit: Public Domain


Jerome S
Jerome S2 years ago


Jim Ven
Jim Ven2 years ago

thanks for sharing.

Dimitris Dallis
Past Member 3 years ago

I never heard of any safe chemical.

Nikki Davey
Nikki Davey3 years ago


Warren Webber
Warren Webber3 years ago

Sign my petition to stop workplace sexual harassment in Ghana


Pamela A.
Pamela A3 years ago


Brian F.
Brian F3 years ago

Amazing how we continue to allow the use of chemical pesticides that we know are poisoning us and our wildlife, and yet we put people in prison for using a harmless plant, marijuana. All chemical pesticides should be banned and made illegal.

Janis K.
Janis K3 years ago

Thanks for sharing.