Fifty-three years after Rachel Carson, in her book Silent Spring, first raised concerns about the safety of the pesticide DDT, the chemical once again is in the news.
Public health researchers in California have published findings that connect maternal exposure to DDT during pregnancy to breast cancer—not in the exposed mothers but rather, 40 or 50 years later, in offspring exposed in utero. The article was published in the Journal of Clinical Endocrinology and Metabolism. In it, the authors looked at the rates of breast cancer in a group of 9,300 women born between 1959 and 1967. Of these, 118 developed breast cancer…
The authors used a well-established study approach called case-control: the 118 daughters with breast cancer (cases) were paired with 354 breast cancer-free daughters born at the same time (controls) and standard clinical variables extracted from each group. In this way, variables like race, maternal weight, lipid profiles, and breast-feeding history could be eliminated as likely causes of any difference in breast cancer rates.
By this analysis, the mothers with high rates of detectable DDT during pregnancy produced daughters who, 50+ years on, had three or four times more breast cancer than daughters of Moms with substantially lower DDT levels. A potentially very big deal for sure.
There is a large and important caveat in the analysis however. The investigators also examined the frequency of breast cancer in mothers, comparing the rate between cases and controls. Here, there was a large and very strong tilt: About 20 percent of daughters with breast cancer had a mom with the disease; in the controls, only 4 percent had a mother with breast cancer. Thus, some and perhaps most of the risk of breast cancer might be explained not by DDT exposure but genetic predisposition.
Which does not exclude DDT as an amplifying effect on genetic risk—but it does deflate some of the headline grabbing excitement the article already has claimed.
The Daily Beast further classifies divergent opinions of the results into Right vs Left instead of the fact that conservative denial is almost wholly grounded in ideology. The counterpoint being individuals and groups dedicated to science and scientific method for progress – a truly conservative style.
That the Daily Beast sees only the conflict between political entities is a reflection of their own tidy journalistic ideology. Historically, properly termed sophistry – that truth lies only safely between opposing contradictions.