The first study on the health effects of exposure over three human generations to DDT, an environmentally toxic chemical, has found that granddaughters whose grandmothers were exposed to the pesticide have higher rates of obesity and an earlier first menstruation. This can increase granddaughters’ risk of breast cancer, as well as hypertension, diabetes, and other cardiometabolic diseases.
Research conducted by the Child Health and Development Studies (CHDS) of the Institute of Public Health and the University of California and published in “Cancer Epidemiology, Biomarkers & Prevention” (a journal of the American Association for Cancer Research), suggests that the effects of the pesticide DDT, despite being banned almost 50 years ago, may contribute to lowering the age of first menstruation and increasing obesity rates among young women today.
The study found that the risk of obesity in young adult granddaughters was 2 to 3 times higher when their grandmothers (who were not overweight) had higher levels of o, p’-DDT (a contaminant of commercial DDT) in their blood during or just after pregnancy. Granddaughters were twice as likely to have earlier first periods when their grandmothers had higher levels of o, p’-DDT in their blood. DDT and related chemicals, including o, p’-DDT, are known to be endocrine disrupting chemicals, compounds that can disrupt and interfere with natural hormones that are essential for development.
«We already know that it is almost impossible to avoid exposure to many common environmental chemicals that are endocrine disruptors. Now our study shows for the first time in people that environmental chemicals like DDT can also pose a threat to the health of our grandchildren, ”says Barbara Cohn, CHDS Director and lead author of the study.
‘Combined with our ongoing studies on the effects of DDT on the generations of grandmothers and mothers, our work suggests that we should take precautionary measures about the use of other endocrine disrupting chemicalsgiven its potential to affect future generations in ways we cannot anticipate today, ”he adds.
The Child Health and Development Studies is a unique project that has followed 20,000 pregnant women and their families for more than 60 years. CHDS enrolled and began tracking pregnant women in the Bay Area between 1959 and 1967, a time of heavy pesticide use before DDT was banned in 1972.
These «Founding grandmothers» The study gave blood samples in each trimester of pregnancy and a sample shortly after delivery. Blood samples were analyzed for levels of DDT and its related chemicals, including active ingredients, contaminants, and their metabolites.
The study focused on o, p’-DDT, as it has previously been linked to breast cancer, obesity, and other detrimental effects on daughters’ health, and it is believed to be the most sensitive biomarker for exposures before and immediately after birth. Since the exposure of the granddaughters would occur through the development of their mothers’ eggs in the womb, the levels of o, p’-DDT are a potential predictor of the results of the exposure of the granddaughters.
“These data suggest that DDT disruption of endocrine systems begins in immature human eggs, decades before the eggs are fertilized,” says Michele La Merrill, associate professor at UCD and co-author of the study. The CHDS study included interviews, home visits, and questionnaires from the daughters and granddaughters of the original enrollees. During home visits, measurements of blood pressure and height and weight were taken.
The current study is based on 365 adult granddaughters who filled out questionnaires, participated in a home visit, had measurements of DDT from the grandmothers’ serum, and (for 285 of them) had information available on the body mass index (BMI) in the grandmothers. three generations. Information on the age of first menstruation was available for the three generations of 235 granddaughters.
Previous CHDS studies have shown that maternal exposure to DDT during pregnancy or immediately after delivery is correlated with an increased risk of breast cancer in daughters and with prevalence of breast cancer risk factors, including obesity, among adult daughters. Other previous studies have linked DDT exposure to birth defects, reduced fertility, and an increased risk of diabetes.