Phthalates Linked to Feminine Behavior in Boys

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Exposure to two common phthalates found in plastics and plastic products appears to cause feminine behavior in preschool age boys, according to a study conducted at the University of Rochester Medical Center. Phthalates are anti-androgens, which means they block the action of male hormones such as testosterone.

Phthalates are chemicals used to soften plastics, and plastics are ubiquitious in our environment. Two phthalates that present a great deal of concern are di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP), both of which can be found in food products. These phthalates are used mainly in polyvinyl chloride (PVC), a product that is involved in food processing, packaging, storage, and heating. Other means of exposure include contact with vinyl and plastic tubing, soaps and lotions, and various household products.

Some research has associated phthalates with conditions such as genital defects, pre-term birth, lowered testosterone levels in infants and adults, and metabolic abnormalities. In 2008, the federal government was concerned enough to pass a law banning six phthalates from being used in the production of toys such as teething rings, dolls, play bath items, and soft books.

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The new study is the first to find that when concentrations of two phthalates in the prenatal urine of women are elevated, their male offspring are less likely to engage in typical male behaviors, such as fighting and playing with trucks. The study group consisted of 145 preschool children. While the presence of DEHP and DBP were associated with less male-typical behavior in the boys, the girls’ play activities were not associated with phthalate concentrations in their mothers.

Researchers are concerned because exposure to anti-androgens such as phthalates has the potential to impact testosterone, which produces the masculine brain. Thus exposure to these chemicals in the womb could impact behavior, as this study suggests. The findings of this current research are also consistent with other study results showing that hormones affect sex differences in the brain.

The lead author Shanna H. Swan, PhD, professor of Obstetrics and Gynecology, director of the URMC Center for Reproductive Epidemiology, and an expert in phthalates, noted in the Center’s news release that phthalates may reduce production of fetal testosterone during a critical period of development, likely within eight to 24 weeks’ gestation, when the testes begin to function. This action could alter brain sexual differentiation.

Previous studies of phthalate exposure during pregnancy have indicated that the chemicals might affect the development of genitals of male rodents and baby boys. While the findings of the current study strongly encourage further investigation as to how these phthalates affect the brain, including feminized behavior in young boys, it is left for consumers, especially women of childbearing age, to try to avoid these chemicals, which may be nearly impossible to do given that they are so pervasive in the environment.

SOURCES:
Gartner S et al. Journal of Agricultural and Food Chemistry 2009 Oct 30
Martino-Andrade AJ, Chahoud I. Molecular Nutrition and Food Research 2009 Sep 16
University of Rochester Medical Center news release

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