A recent study has reportedly claimed that male deer mice exposed to bisphenol A (BPA) through maternal diet “showed no changes in external phenotype, sensory development, or adult circulating concentrations of testosterone and corticosterone, but spatial learning abilities and exploratory behaviors were severely compromised compared with control males.” Eldin Jašarevic, et al., “Disruption of adult expression of sexually selected traits by developmental exposure to bisphenol A,” Proceedings of the National Academy of Sciences, June 27, 2011. According to University of Missouri researchers, “adult male-male competition for mates in this species is supported by enhanced spatial navigational and exploratory abilities, which enable males to search for prospective, widely dispersed females.” But males exposed to BPA in utero and while nursing allegedly lost their spatial-navigation skills when running a maze, as well as their ability to attract females, which evidently preferred the control group on a 2-to-1 basis.
As lead author Cheryl Rosenfeld explained in a June 27, 2011, PBS article, “Non-BPA exposed males can almost immediately get to the correct hole [in a maze]. The BPA exposed male took quite a bit longer. They didn’t use the most efficient strategy and just wandered around aimlessly.” Her team had hypothesized that if male deer mice were exposed to BPA “when testosterone begins programming the brain, later behaviors would be affected,” and in particular “sexually selective traits, or behaviors that are differently expressed between males and females.”
“Clearly males and females do not react to this chemical in the same way,” Rosenfeld concluded. “Many previous studies have been generic testing rather than being tailored to factors that are relevant to a particular species and behaviors that are consistent with whether they are male or female. If you test behaviors that are not important to that gender, you may or may not get an effect.”