Pesticides disrupt our hormones for generations - even women whose grandmothers were exposed to the chemical have higher risks of obesity and breast cancer, scientists say

• A new study found women whose grandmothers had DDT exposure are more likely to be obese and have early periods.
• DDT was a widely used insecticide that's been banned in the US since 1972.
• Early onset periods are a risk factor for breast cancer and heart conditions.

There's evidence that DDT, a pesticide previously used to kill insects like mosquitoes, is still wreaking havoc on human health four decades since the government banned it.

In 1972, Congress banned DDT, or dichlorodiphenyltrichloroethane. Since then, evidence has emerged - first in wildlife and then in humans - that the pesticide left an enduring mark on health.

According to a study published April 14 in the journal Cancer Epidemiology, Biomarkers & Prevention, the granddaughters of people who were exposed to DDT while pregnant are more likely to be obese, have early-onset periods, breast cancer, high blood pressure, and diabetes.

To study the effects of DDT, researchers at UC Davis and the Public Health Institute in Oakland used archived blood samples from 15,000 women who were pregnant when DDT was still used. The researchers then worked with these women's daughters and granddaughters, collecting their blood samples to see how DDT impacted them before they were born.

Researchers found that women in their 20s and 30s with grandmothers who were exposed to DDT are between two and three times more likely to be obese and two times more likely to have their periods start earlier than usual - around the age of 11.

Early-onset menstruation can lead to other health conditions later in life, like breast cancer, high blood pressure, and diabetes, according to the study authors.

"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," Barbara Cohn told the LA Times. Cohn is director of the Public Health Institute's Child Health and Development Studies, the institution that researched the 15,000 women who gave blood samples decades ago.

'Forever chemicals' are ruining reproductive abilities and overall health

This isn't the first study to find chemicals' lasting impact on human health.

An October 2007 study in the journal Environmental Health Perspectives found the daughters of pregnant women exposed to DDT were more likely to develop breast cancer. The researchers of the study also found children who had DDT exposure were five times more likely to develop breast cancer.

In addition to DDT, chemicals in plastics like water bottles are altering human reproductive abilities, Insider previously reported.

"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," Cohn told the LA Times.