WASHINGTON—Baby boys are far more likely to have smaller, less developed genitals if their mothers had high levels of chemicals commonly found in cosmetics, detergents, medicines and plastics, a study released Friday said.
The higher the levels of the chemical compound phthalates in the mothers during the final months of pregnancy, the less masculine their boys were when examined by pediatricians, said the study's lead author, Shanna Swan, a professor of reproductive epidemiology at the University of Rochester.
"We were able to show, even with a relatively small sample, that phthalate-exposed boys have an increased likelihood of a cluster of genital changes," Swan said Thursday.
The infant sons of the high phthalate-level moms had more instances of smaller penises and scrotums and not properly descended testicles, according to the peer-review study published in the journal Environmental Health Perspectives. Boys of highly exposed moms were four to 10 times more likely to have reduced genital development.
The most glaring difference between exposed boys was in the anogenital distance, the measurement from the genitals to the anus. In males it is twice the size of females, and smaller distances have been shown in animal studies to indicate reduced testosterone levels.
Nine of the 10 boys exposed to the highest mix of different phthalates had short anogenital distances. Only one of the 11 boys with the least phthalate exposure had a short measurement, Swan said.
Scientists are concerned that these boys might go into puberty late, be infertile and contract testicular cancer because that's what rats with similar reduced anogenital distances showed, said Earl Gray, a senior research biologist at the U.S. Environmental Protection Agency.
The mothers in the federally funded study—including those with high phthalate levels—showed similar levels in the range and amounts of the chemicals as the average American, based on previous Centers for Disease Control and Prevention studies, said study co-author Antonia Calafat, the CDC's lead research chemist.
"If I were pregnant, I would try to keep my phthalate levels low," said study co-author Christine Ternand, a professor of pediatric endocrinology at the University of Minnesota. "How I would do that would be a tricky thing."
Phthalates are used as plasticizers, solvents, coatings and perfume fixatives. They are in hundreds of products, including food packaging, coatings on time-released medicines, soap, shampoo, nail polish, hair sprays, detergents, and vinyl floor coverings.
The European Union has restricted use on some phthalates based on similar problems found in rat studies. Legislatures in California and New York are also looking into limited bans.
Earlier this month, the U.S. Food and Drug Administration said that at the moment the agency "does not have compelling evidence that phthalates, as used in cosmetics, pose a safety risk."
Marian Stanley, a senior director of the American Chemistry Council and spokeswoman for a group of companies that use phthalates, said it was too hard to come to any conclusion from the Swan study, especially since it involved too few people.
Irene Malbin, a spokeswoman for the Cosmetic, Toiletry and Fragrance Association, said "an extensive body of scientific research and data" shows that phthalates in cosmetics are safe.
But environmental groups have been saying otherwise for years.
"If you have a chemical out there that's shown is harming kids, you need to do something about it," said Tim Kropp, a toxicologist for the Environmental Working Group. "It's kind of sad that we had to wait for children to be harmed."
Numerous rodent studies found smaller genitals in phthalate-exposed males, but Swan's study is the first to look for the problem in humans.
"In the rats and in the babies, they (children of mothers with high phthalates) are less masculine," said Paul Foster, a reproductive toxicologist with the National Institute of Environmental Health Sciences.
In rodents, studies have shown a cause-and-effect link, but the human study is only an association so far, said Foster.
"What these phthalates do is inhibit the production of testosterone in the testes and that's what is really important," Foster said. "Because it's the fetal testes that drives the normal development of the male plumbing."
But in rats, undeveloped males often grow out of short anogenital distance problems, said toxicologist Rochelle Tyl of the private research company RTI International.
"It may not be permanent. It may be transient," she said.
The study, conducted in Minneapolis-St. Paul; Columbia, Mo.; and Los Angeles, examined 85 infant boys and used urine samples taken from their mothers during the last few months of pregnancy. The National Institutes of Health and the U.S. Environmental Protection Agency paid for it.
For more information check out the following Web sites:
The study in Environmental Health Perspectives is at:
The cosmetics' industry statement on phthalates is at:
Activists who want to restrict phthalate use have a Web site at:
The Food and Drug Administration's questions and answers on phthalates and cosmetic products:
(c) 2005, Knight Ridder/Tribune Information Services.
Need to map