From Grist (and Sandra Steingraber is one of my favorite environmental writers). This could have huge impacts on breast cancer (which i estrogen driven), fertility, etc.:
Over the course of just a few decades, the childhoods of U.S. girls have been significantly shortened. Girls get their first periods, on average, a few months earlier than did girls 40 years ago. But they get their breasts, on average, one to two years earlier. Recent studies show that the advent of breast budding -- one of the earliest visible signs of puberty -- appears to be arriving earlier and earlier in the lives of U.S. girls. We need to know why.