DDT Exposure During Pregnancy May Raise Breast Cancer Risks: Study

Children whose mothers who were exposed to the pesticide DDT during pregnancy may face a higher risk of developing breast cancer as adults, according to the findings of new research. 

In a study published this week in The Journal of Clinical Endocrinology & Metabolism, researchers determined that women whose mother’s had higher levels of the pesticide Dichlorodiphenyltrichloroethane (DDT) in their bodies while they were pregnant with them were four times more likely to develop breast cancer as adults, when compared to women whose mothers were not exposed to the chemical.

The case-controlled study involved a 54 year followup for more than 20,000 pregnancies, resulting in 9,300 daughters in the Child Health and Development Studies pregnancy cohort focused on women who were Kaiser Foundation Health Plan members who received obstetric care in Alameda County, California, between 1959 and 1967.

Researchers were able to use 50 year old blood samples to determine how much DDT was in the pregnant women’s systems.

A total of 118 women who were born to DDT-exposed mother’s were diagnosed with breast cancer, compared to 354 women who were daughters of women who were not exposed to DDT.

“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, co-author of the study.

DDT Health Concerns

DDT was first used in the U.S. in 1945 to fight mosquitoes that carried diseases like malaria. It became heavily used in the 50s and 60s; but was phased out when it began to affect wildlife, causing declines in the populations of bald eagles and ospreys. DDT use continues in Africa and Asia.

Many women were exposed to DDT during the time it was in widespread use. The children of those women are now coming to an age where the risk of breast cancer is heightened.

In utero exposure to diethylstilbestrol, another xenoestrogen, has also been linked with increased risk of breast cancer.

Breast cancer affects more than 200,000 women a year in the U.S., killing more than 40,000. There is no known direct cause, yet genetic mutations typically raise the risk, as does obesity, poor diet, cigarette smoke, the miscarriage drug DES and lack of exercise.

“Experimental studies are essential to confirm results and discover causal mechanisms,” said Cohn. “Findings support classification of DDT as an endocrine disruptor, a predictor of breast cancer, and a marker of high risk.”