When expectant mothers are exposed to either of two phthalates, their sons are less likely to play with typical male toys such as trucks or engage in typical boy scuffles, according to a study published recently in the International Journal of Andrology.
The study links less-than-typical behavior by boys ages 4-7 with normal prenatal levels of either dibutyl phthalate or diethylhexyl phthalate two of three phthalates the federal government has banned from toys and child-care articles.
Steve Risotto, senior director of the Phthalates Ester Panel of the American Chemistry Council in Arlington, Va., said the way the mothers were selected, and the failure to use a third party to evaluate the children's behavior, casts doubt on the validity of researchers' conclusions.
The mothers were picked from a pool of people [in the 2005 study] who were already biased against phthalates, Risotto said in a telephone interview. So you wind up [with] a tremendous potential to bias the results, since the mothers evaluated the behavior of their children.
There is a strong potential that the mothers were biased that their sons were emasculated, he said.
The research team, led by Dr. Shanna Swan of the Rochester School of Medicine, said there is no evidence that any other forms of phthalate metabolites in mothers affect behavioral patterns of young boys. The study showed no behavioral changes in young girls.
Swan is director of the Center for Reproductive Epidemiology at the University of Rochester School of Medicine and Dentistry; a member of the Environmental Health Sciences Center funded by the National Institute of Environmental Health Sciences (NIEHS); and principal investigator of the Study for Future Families, which is examining the health effects of phthalates and other chemicals.
Other groups involved in the research were Harbor-UCLA Medical Center and Cedars-Sinai Medical Center, both in Los Angeles; the University of Minnesota Health Center in Minneapolis; and University Physicians Hospital in Columbia, Mo.
Our findings on boys' behavior suggest that early exposure to [DHEP and DBP] can influence their brain development [and that] the implications are potentially profound and far-reaching, Swan said.
Risotto disagreed: It is a real stretch to make that conclusion, because you don't have any data on neurological effects. I scratch my head as to whether this statistical analysis has any validity.
He also faulted the study's limited size (74 boys and 71 girls), that it didn't consider other environmental factors mothers were exposed to, and the number and gender of the subjects' siblings.
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