By Janet Raloff
From New Orleans, at the e.hormone 2004 conference
Although production and use of DDT have been banned throughout most of the world for decades, people continue to carry the pesticide’s residues in their bodies. That’s a concern because animal studies have shown that DDT can mimic the action of some hormones and derail the normal development of reproductive tissues (SN: 2/5/00, p. 87: Available to subscribers at DDT treatment turns male fish into mothers). A new study conducted in China’s rural Anhui province indicates that at DDT concentrations present in young women there, the pesticide can not only affect menstrual cycles, but also can foster miscarriages in the first few weeks of pregnancy.
Scott A. Venners of the Harvard School of Public Health in Boston and his colleagues studied 388 newly married, nonsmoking textile workers who were attempting to get pregnant. Blood tests of each woman indicated how much of DDT and its breakdown products were stored in her body. Each woman also submitted a daily urine sample for analysis of human chorionic gonadotropin (hCG), a hormone whose concentration in urine rises sharply within a week or so after conception. In some women, hCG concentrations rose only to plummet a few weeks to a month later, signifying a miscarriage.
After stratifying the women into three groups on the basis of blood DDT concentrations, the researchers found that each additional 10 nanograms of the pesticide per gram of serum increased a woman’s chance of early miscarriage by 17 percent. Women in the highest-exposure group—with a mean concentration of 53 ng of DDT per gram of serum—were twice as likely to miscarry within the first 6 weeks of pregnancy as were women in the lowest group, with a mean serum DDT concentration of only 16 ng/g. However, Venners notes, among women who were far enough along to know they were pregnant, no difference in miscarriage rates emerged among the different DDT-exposure groups.
