Boston, MA – Healthy, nonsmoking women with high levels of DDT residues in their bloodstream are far more likely to miscarry during the early weeks of pregnancy than those with lower levels, a study by researchers at the Harvard School of Public Health found.
The study, to be published in the October 5 issue of the American Journal of Epidemiology (an Oxford University Press journal), looked at 388 newly married, healthy female textile workers in China, between the ages of 20 and 34 years old, who were attempting to get pregnant. The results found that those who had the highest levels of DDT residues in their bloodstream were most likely to miscarry during the early weeks of pregnancy, before the women even realized they were pregnant. The researchers initially screened a group of 961 recently married women, full-time workers for the study, excluding 452 due to not meeting data collection requirements such as failure to collect a daily urine samples, continued use of contraception, drank alcohol or were current smokers.
DDT production and its use were banned decades ago throughout most of the world, including China, due to concerns about its biologic persistence and potentially harmful effects on humans and animals. However, most people continue to carry the chemical’s residue in their bodies, even if they live far from areas where DDT was used or produced. DDT is a persistent organic pollutant, meaning it circulates globally and does not break down but instead lingers in the environment. The average level of DDT residues found in the blood of the Chinese women in this study were about 10 times higher than those ordinarily found in the United States, but similar to levels found in some countries where DDT was more recently used.
As the level of DDT residues found in a woman’s preconception blood sample rose, so did the risk of early miscarriage, the study found. Researchers found that for every additional 10 nanograms of DDT per gram of serum, a woman’s chance of early miscarriage rose by about 17 percent. The study did not investigate whether DDT was linked to infertility.
“Although more research in this area is needed, we can see that DDT exposure could have serious consequences on human reproduction,” said Scott Venners, lead author of the study and a research associate in the Department of Environmental Health at the Harvard School of Public Health.
The research was supported by grants from the National Institute of child Health and Human Development, the National Institute of Environmental Health Sciences and the U.S. March of Dimes Birth Defects Foundation.