A new study in the International Journal of Andrology has raised a storm of concern that prenatal exposure to these chemicals could make boys less masculine in their play preferences.
Phthalates, which block the activity of male hormones such as androgens, could be altering masculine brain development, according to Shanna H. Swan, a professor of obstetrics and gynecology at the University of Rochester Medical Center and lead author of the new report [Los Angeles Times]. To test whether that link extended into behavior, Swan’s team tested women for phthalate levels midway through their pregnancy and then checked back in on the children four to seven years later.
The researchers asked parents to report their children’s patterns of play, but they knew they also had to separate any potential phthalate effect from the “nuture ” side of question. To determine how parental views might sway behavior, parents completed a survey that included questions such as, “What would you do if you had a boy who preferred toys that girls usually play with?” They were asked to respond with whether they would support or discourage such behavior, and how strongly [TIME].
The study of about 150 kids found that while girls were mostly unaffected, boys who had been exposed to the highest phthalate levels showed a lower likelihood than other boys to participate in what we consider typical rough-and-tumble male recreation—play fighting, pretending to play with guns, and so on. But the research might not imply the national masculinity crisis that some headlines suggest. Play in the most highly phthalate-exposed boys wasn’t “feminized,” Swan explains, since these kids didn’t preferentially play with dolls or don dresses. Rather, she says, “we’d describe their play as less masculine” [Science News]. Rather than play-fighting, she says, those boys tended toward “gender neutral” play like putting puzzles together or competing in sports.