Fertility Study Finds DDT's Legacy

The report by the Public Health Institute in Berkeley is the first scientific evidence that DDT that collects in women's bodies can affect their female offspring many years later, when they reach adulthood and attempt to reproduce.

The findings support a controversial theory that pesticides and other environmental contaminants that mimic sex hormones are altering human fertility and health.

DDT was used worldwide in the 1940s through 1960s for pest control. Banned in the United States and most of the world, it is still used in parts of Africa, Southeast Asia, South America and Latin America to control malaria-carrying mosquitoes. Many Americans still have the pesticide and its byproducts in their bodies, and they continue to be exposed through produce grown in tropical countries, as well as fish caught in some U.S. waters, particularly in the Los Angeles area.

The Berkeley team measured the pesticide in stored blood that had been drawn between 1960 and 1963 from new mothers in the Oakland area. Then the researchers questioned the daughters of those women to calculate how long it had taken them to conceive.

On the basis of responses from 289 women, the scientists found that the length of time it took for the women to get pregnant correlated strongly with the amount of DDT in their mother's blood, according to the study, which was published in the British journal Lancet.

To their surprise, the scientists also found that a common breakdown product of DDT seemed to have the exact opposite effect: The more DDE in the mothers, the less time it took for the daughters to become pregnant.

Scientists say that the unexpected, mixed results of the new study show that hormone-disrupting chemicals work in a complicated way on human bodies that no one yet understands. The results indicate that a woman's fertility can be altered in sometimes inexplicable ways by what her mother was exposed to decades earlier.

"This raises the specter that the chemical cocktail we are all exposed to is altering our human reproductive capability," said the study's lead researcher, Barbara Cohn, director of the Center for Research on Women's and Children's Health at the Public Health Institute, which is one of the largest nonprofit public health agencies in the country.