DDT was among the first recognized endocrine disruptors, according to the introductory guide to endocrine-disrupting chemicals published by the Endocrine Society and IPEN. DDT and related pesticides can mimic and interfere with the function of the hormone estrogen. Past studies have found DDT exposure is linked to birth defects, reduced fertility and increased risk of Type 2 diabetes.
“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 one of the study’s authors, Barbara A. Cohn, PhD, of the Public Health Institute in Berkeley, Calif. “Environmental chemicals have long been suspected causes of breast cancer, but until now, there have been few human studies to support this idea.”
The case-control study is prospective, having tracked the daughters of women who participated in the Child Health and Development Studies (CHDS) for 54 years beginning in utero. CHDS studied 20,754 pregnancies among women who were members of the Kaiser Foundation Health Plan from1959 through 1967. CHDS participants gave birth to 9,300 daughters during that period.
For the analysis published in JCEM, researchers used state records and a survey of CHDS participants’ grown daughters to determine how many were diagnosed with breast cancer by age 52. To determine levels of DDT exposure in utero, the researchers analyzed stored blood samples from CHDS to measure DDT levels in the mothers’ blood during pregnancy or in the days immediately after delivery. The researchers measured DDT levels in mothers of 118 women who were diagnosed with breast cancer. The scientists identified 354 daughters who did not develop cancer to use as controls and tested their mothers’ blood for comparison.
The researchers found that independent of the mother’s history of breast cancer, elevated levels of o,p’-DDT in the mother’s blood were associated with a nearly fourfold increase in the daughter’s risk of breast cancer. Among the women who were diagnosed with breast cancer, 83 percent had estrogen-receptor positive breast cancer, a form of cancer that may receive signals from the hormone estrogen to promote tumor growth.
Researchers also determined that exposure to higher levels of o,p’-DDT was associated with women being diagnosed with a more advanced stage of cancer. In addition, the scientists found women with greater exposure to o,p’-DDT were more likely to develop HER2-positive breast cancer, where the cancer cells have a gene mutation that produces an excess of a specific protein. Basic research studies where breast cancer cells were exposed to DDT have found the pesticide activated the HER2 protein.
A study conducted over a 50-year period involving three generations of American women who had been exposed to the estrogen mimicking chemical DDT while in the womb are nearly four times more likely to develop breast cancer.
Many women maintain hints of DDT in their bodies due to the pervasive use of the chemical before it was banned in the United States during the 70’s. It was sprayed from planes and trucks into fields, into cities and over residences with or without permission, and was advertised for use in homes. This pesticide killed not only harmful insects, but also beneficial insects, fish and birds. Decades later, they find that is has also been hurting women.
The study reacted mothers and daughters over the course of 50+ years. One third of the daughters being reacted were diagnosed with breast cancer by the age of 52.
Scientist performing this study theorized that exposure to DDT in uterine could alter a woman’s genes and ultimately the formation of breast tissue, increasing the risk.
According to state records for California, the State sprayed for leaf hoppers, mosquitos, along with flies and their larvae during the month of July 1961 throughout the San Joaquin Valley. This is the place of my birth…where my Mother was during her entire pregnancy with me…makes a person wonder! I wonder how many of us might have been affected by this chemical?
I have actually e-mailed the woman who conducted the study so I could get more information. I will relay this info when I get it.