DDT’s Toxic Legacy Could Span Three Generations

More than 50 years ago, scientists at the Kaiser hospital in Oakland started a simple experiment: When a pregnant woman would come in for routine maternal care, they were asked to give a sample of blood, to be frozen for future research. They didn’t know it at the time, but those samples would later be key in understanding the long-term health impacts of DDT.

…“People thought of this chemical as a miracle, because it was very good at controlling the mosquito that transmits malaria,” said Barbara Cohn, director of the Public Health Institute’s Child Health and Development Studies program. “It was one of the most ubiquitous exposures in human history”

… in the early 2000s, Cohn found a new source of potential answers — in the bank of frozen blood taken from pregnant women at Kaiser during the ‘50s and ‘60s. The library, which had grown to include blood samples from around 15,000 women, was a priceless cache of biological data from which DDT’s effects could be analyzed.

“These data, which are 60 years old, are the only data like this in the world,” Cohn said.

Cohn’s team got to work: They tested each woman’s blood sample for DDT, then searched California’s cancer registry to see if she eventually developed breast cancer. They found that women who were exposed to DDT at specific periods in their life were more likely to develop breast cancer later in life. In other words, a woman’s cancer risk wasn’t just determined by how much DDT she was around, but when she was around it.