Swan said her team found "a cluster of small genital changes" associated with low-dose exposure to four phthalates.
One of the most important findings was that the phthalate levels associated with the genital changes "were not unusually high" for the general population, according to the study, which was funded by the National Institutes of Health and the EPA.
For The Record
Los Angeles Times Saturday May 28, 2005 Home Edition Main News Part A Page 2 National Desk 1 inches; 54 words Type of Material: Correction
Genital abnormalities -- An article in Friday's Section A about a study linking phthalates, compounds used in plastics and cosmetics, with genital abnormalities in boys stated that Europe had prohibited using phthalates in cosmetics. Europe has banned two major types of the compounds in cosmetics, but other phthalates are still legal in the products.
Nearly everyone in a 1999-2000 survey of 2,500 people throughout the United States had phthalates in their urine, and the effects in the babies were seen at concentrations below those detected in the urine of 25% of them, according to the results of the testing by the Centers for Disease Control and Prevention.
Some scientists specializing in reproductive health say that finding anatomical changes in infants related to a chemical is disturbing, even if their health is not shown to be affected.
But Marian Stanley, manager of a phthalates panel at the American Chemistry Council, said the authors did not report any negative health effect on the babies, and that the differences in their genitalia have "no known significance" and could be caused by natural variability, not chemical exposure.
"As of now, the authors have yet to demonstrate that their data are solid, or that they are meaningful," Stanley said.
Several scientists ruled out the Chemistry Council's assertion that the results could be due to natural variations in boys. Kim Boekelheide, a professor at Brown University's department of pathology, who studies the testicular effects of phthalates on animals, said the associations between the chemicals and the babies' genital effects "are strikingly strong. Overall, this is a very important study."
Boys exposed to the highest levels of the chemicals were 4 to 10 times more likely to have the genital changes. The Los Angeles-area mothers were patients of prenatal clinics at Harbor-UCLA Medical Center and Cedars-Sinai Medical Center.
Swan emphasized that none of the abnormalities was serious enough to be considered birth defects.
Dr. Larry Lipshultz, a professor of urology at Baylor College of Medicine in Houston, said there is no "normal" anogenital length for boys. It is measured often in lab animals, and sometimes in girls, but rarely in boys.
