By Janet Raloff
Exposures in the womb to a ubiquitous family of industrial chemicals can subtly perturb preferences of boys for certain types of child’s play thought to be hardwired in the brain, a new study suggests. Phthalates are widely used solvents and plastics softeners. In this study, the greater a boy’s fetal exposure to certain phthalates, the less often he tended to engage in typically masculine play.
Girls’ play was unaffected, according to the study, set to be published in an upcoming International Journal of Andrology.
The reason boys like trucks and girls like dolls relates to fetal differences in brain development, explains Heather Patisaul, a neuroendocrinologist at North Carolina State University in Raleigh. Males develop differently from females — physically and behaviorally — only through programming by androgens, male sex hormones such as testosterone, she says In animals, anything that dampens the testosterone signal during fetal development, such as a chemical or genetic defect, can trigger a subtle demasculinization in males.