Phthalates Affect Way Young Boys Play
Boys With High Phthalate Exposure in Womb Show Less Masculine Play
Nov. 16, 2009 -- Mothers exposed to high levels of chemicals known as
phthalates during pregnancy may have boys who are
less likely to play with trucks and other male-typical toys or to play fight,
according to a new study.
Phthalates, common in the environment, are found in toys, food packaging,
personal care products, nail polish, adhesives, and other products.
In the study, the researchers focused on two phthalates of concern to
environmental experts, DEHP and DBP. They tested the urine of women during
the 28th week of pregnancy and divided them into four groups depending on the
concentration of phthalate metabolites or breakdown products. Then they
assessed the play behavior of the 145 children when they reached age 3 to
If mothers were in the highest concentration group, the chance that their
boys had a less masculine score was five times greater than mothers in the
lowest concentration group, according to study researcher Shanna Swan,
PhD, professor of obstetrics and gynecology at the University of Rochester
Medical Center's Center for Reproductive Epidemiology and an expert on
''I'm not saying these boys are feminized," Swan tells WebMD. Rather, she
says, ''they are less likely to play in a male-typical manner." No effect was
found with the girls.
Swan and other experts suspect that exposure to the chemicals affects the
level of testosterone crucial for the development not only of male reproductive
organs, but also the masculine brain. ''We now suspect that the phthalate [exposure]
affects the entire body, not just the reproductive tract,'' Swan says.
The study is published in the International Journal of Andrology.
Exposure to Phthalates
Swan and her colleagues tested urine samples of 74 pregnant women who gave
birth to boys and 71 who gave birth to girls, looking for nine different
phthalates. The women were part of The Study for Future Families, an ongoing
When the children were ages 3.6 to 6.4 years, Swan's team asked the mothers
to answer questions about their children's play behavior. Parents described the
type of toys and play their children favored, and each child was given a score
reflecting masculine-typical play or feminine-typical play.
Exposure to two of the nine phthalates, DEHP and DBP, was associated with
less masculine play behavior, the researchers found.
For example, Swan says, ''If the mother's MEHHP concentration [one of the
phthalate metabolites] was high, in the upper quartile, the odds that her boy
had a score that was less masculine [in play behavior] was five times
greater than mothers whose MEHHP was in the lowest quartile."
Exposure to phthalates may lower testosterone production in the fetus during a crucial period
of development, at about 8 to 24 weeks' gestation, Swan says, when the testes
begin to function, and in doing so alter sexual differentiation in the