In the News

DDT in Pregnancy May Raise Breast Cancer Rates in Daughters

Women who were exposed to higher levels of the pesticide DDT in utero were nearly four times more likely to be diagnosed with breast cancer as adults than women who were exposed to lower levels before birth, according to a new study published in the Journal of Clinical Endocrinology & Metabolism. “This 54-year study is the first to provide direct evidence that chemical exposures for pregnant women may have lifelong consequences for their daughters’ breast cancer risk,” said Barbara A. Cohn, PhD, director of PHI's Child Health and Development Studies and one of the study’s authors.

Women whose mothers had higher levels of DDT in their blood while pregnant were nearly four times more likely to develop breast cancer as adults, a new study finds.

The report provides one of the strongest links yet between exposure to DDT – still widely used globally – and cancer. It’s especially reliable because the researchers found 50-year-old blood samples to show how much DDT was in the pregnant women’s systems, rather than rely on possibly faulty memories or other indirect measurements.

“Environmental chemicals have long been suspected causes of breast cancer, but until now, there have been few human studies to support this idea,” said Barbara Cohn of the Public Health Institute in Berkeley, California, who worked on the study.

“This 54-year study is the first to provide direct evidence that chemical exposures for pregnant women may have lifelong consequences for their daughters’ breast cancer risk.”

Breast cancer affects more than 200,000 women a year in the United States, and kills more than 40,000. Most cases are sporadic — there’s no direct known cause. Obesity, poor diet and a lack of exercise are very strong factors, and there are some genetic mutations that greatly raise the risk.

And while women often fear that environmental contaminants may raise the risk, there are only a few studies that show chemicals do affect it. The chemicals in cigarette smoke are a known risk factor, as is the drug DES, used in the 1950s and 60s to prevent miscarriages.

One study showed that women who worked with certain cancer-causing solvents also have a higher risk. But no study has so strongly demonstrated that DDT can raise the risk.

“Currently no direct evidence links in utero dichlorodiphenyltrichloroethane (DDT) exposure to human breast cancer,” Cohn and colleagues wrote in their report, published in the Journal of Clinical Endocrinology and Metabolism.

If their findings hold true, the consequences could be far-reaching, they said.

“Many women were heavily exposed in utero during widespread DDT use in the 1960s. They are now reaching the age of heightened breast cancer risk,” Cohn’s team wrote.

“DDT exposure persists and use continues in Africa and Asia without clear knowledge of the consequences for the next generation.”

Read the full article on

This study was picked up by many other media outlets. Read stories from The Washington PostForbesTIME MagazineNational GeographicCBS NewsFox News, PRI’s Living on Earth and Le Monde.


More Updates

Work With Us

You change the world. We do the rest. Explore fiscal sponsorship at PHI.

Bring Your Work to PHI

Support Us

Together, we can accelerate our response to public health’s most critical issues.


Find Employment

Begin your career at the Public Health Institute.

See Jobs

Aerial view of wildfire smoke


Wildfires & Extreme Heat: Resources to Protect Yourself & Your Community

Communities across the U.S. and around the world are grappling with dangerous wildfires and extreme heat. These threats disrupt and uproot communities and pose serious risks to environmental and community health—from rising temperatures, unhealthy air pollutants, water contamination and more. Find PHI tools, resources and examples to help communities take action and promote climate safety, equity and resiliency.

Get started

Continue to