In the patriarchy (that's Women's Studies for "dicktopia") we live in, there is pretty much no worse fate than wussification. So in a way, we're glad to hear that Bisphenol A, an organic compound found in a lot of plastics, makes male mice act less masculine. Maybe this will induce Girl Panic in some of the straight dudes who run things, and we can finally get the stuff taken out of our baby bottles, plastic packaging, and cans.
According to an article published in the Proceedings of the National Academy of Science, deer mice exposed to BPA in utero (the way many human fetuses would be) showed diminished ability to navigate mazes. That sounds like the BPA mainly just made them dumb, but researchers swear that male deer mice have notably better spatial skills, and that the males were just navigating like ladies. (Of course, the researchers also say that we could test this in humans based on "Does the boy go after male toys or after female toys?" which suggests that a) they think toys have genitals b) they think BPA can affect gender socialization. So, you know, grain of salt.) Females were also only half as interested in males who had been exposed to BPA.
Of course, you always have to be cautious when applying the results of animal studies to humans, but this is hardly the first animal study showing harmful effects from BPA, which many scientists believe can disrupt the endocrine system. Other studies have raised concerns about accelerated puberty, heart disease, diabetes, and cancer from BPA exposure, and nine states have BPA bans. But none of those have to do with manly masculine manliness!