DDT was a pesticide commonly used in the 1960s, but its use was banned in the US in 1972 due to health problems.
Study co-author Barbara A. Cohn, the Public Health Institute in Berkeley, California, and colleagues report their findings in the Journal of Clinical Endocrinology and Metabolism .
more than 5 decades, DDT (dichlorodiphenyltrichloroethane) is widely used to prevent insects from the destruction of agricultural crops or spread of diseases, such as malaria and typhus.
While regions such as Africa and Asia still use DDT to reduce the spread of malaria, pesticide use was banned in the US in 1972, as well as in many other countries in the following years.
DDT bans came into force after the chemical was identified as an endocrine disruptor – meaning that interferes with hormone function estrogen . Previous research has also linked prenatal exposure to pesticides developmental problems in children , an increased risk of birth defects, reduced fertility and increased risk of high blood pressure in women.
According to Cohn, who has long been suspected that exposure to environmental chemicals such as DDT can also be linked to cancer breast . “But so far,” he adds, “there have been few human studies to support this idea.”
As such, Cohn and colleagues evaluated the risk of breast cancer among 9,300 women in the US born between 1959 and 1967 – a period when the use of DDT was common in the country.
Women are born to mothers who were part of the Child Health and Development Studies (CHDS) and followed them for 54 years from when they were in the womb of his mother.
To identify the levels of exposure to DDT among the daughters in the womb, assessed stored blood samples that were taken from their mothers during pregnancy or within a few days after birth.
The use of state records and health questionnaires completed by daughter during 54 years of follow up, the team was able to identify how many daughters were diagnosed with breast cancer.
Study provides “direct evidence” of the relationship between prenatal exposure to DDT and breast cancer
Breast cancer was identified in 118 daughters during follow-up blood samples from their mothers by DDT levels were evaluated and compared with blood samples from mothers of 354 daughters who were not diagnosed with breast cancer.
The team found daughters of mothers who had higher levels of o, p’-DDT in their blood samples – a form of commercial DDT known as one of the strongest endocrine disruptors – were 3.7 times more likely to developing breast cancer, compared with the daughters of mothers who had lower levels of this DDT in blood.
This finding held true even after considering the history of the mother of breast cancer, according to researchers.
The team points out that 83% of breast cancers identified in the study were the estrogen receptor positive – in which breast cancer cells contain estrogen receptors that can receive signals from the hormone to stimulate growth.
In addition, the study revealed that exposure to high levels of o, p’-DDT in the womb was associated with a greater likelihood of being diagnosed with a more advanced form of breast cancer.
The team also found that women with higher exposure to or, p’-DDT were more likely to develop HER2-positive breast cancer – in which the cells of breast cancer contain a mutation that causes the excess receptors epidermal growth factor human 2 proteins (HER2). The researchers note that previous studies have found DDT can activate HER2.
Commenting on their findings, Cohn says:
“This study 54 is the first to provide direct evidence that chemical exposures for pregnant women can have lifelong consequences for the risk of breast cancer her daughters.
This study requires a new emphasis on finding and control of environmental causes of breast cancer operating in the womb. “
Cohn says that their findings should also encourage further studies that may lead to prevention, early detection and treatment strategies for many women with breast cancer related to DDT-who were exposed to pesticides in the womb.
“We also continue to look for more chemicals to see what can affect the risk of breast cancer among the study participants cancer,” he added.
In January 2014, Medical News Today reported on a study that found that exposure to a byproduct of DDT – called dichlorodiphenyldichloroethylene (DDE) – May raise the risk of Alzheimer’s disease .