Bad for the boys
By Alison Motluk BREAKDOWN products from the pesticide DDT have been detected for the first time in the amniotic fluid of pregnant women. Claude Hughes of the Cedars-Sinai Medical Center in Los Angeles and Siu Chan of the University of Calgary in Canada led a study of amniotic fluid from 53 women in the Los Angeles area who were between 16 and 20 weeks pregnant. Thirty per cent of the samples contained detectable levels of DDE—a breakdown product of DDT, long outlawed in developed countries. DDE can bind to and inactivate cell receptors for the hormone testosterone, which plays an important role in the masculinisation of boys. Male fetuses tend to have about twice as much testosterone in their blood as females, but concentrations of DDE in amniotic fluid ranged from 0.1 to 0.63 nanograms per millilitre—approaching the level of testosterone normally found in female fetal blood. The researchers fear that such levels could have a long-term effect on male development and reproductive health, by reducing the amount of testosterone binding to receptors. Although the researchers cannot be sure whether the DDE has any adverse effects, Chan cites the example of alligators in Florida that were exposed to the chemical after a spill. “In males, the penis was much smaller than normal,” he says. Hughes, who presented the results at an Endocrine Society meeting in San Diego last week, fears that DDE might lead to a low sperm count in adulthood: “How much interference do you have to have before there is a change in the sex hormone-related development of several structures?