We’ve known for quite a while now that girls are beginning menstruation at a younger age than ever. I’ve blogged about the link between increased exposure to hormone-disrupting chemicals and decreased age of menstruation in girls before. It looks like girls are not alone.

In a recent study published in the journal Pediatrics, no less, researchers found that boys are entering puberty six months to two years earlier than they did only 30 to 40 years ago. This is the first study of its kind in boys in the United States, but studies in Denmark, Sweden, Great Britain, Italy, and China have found earlier puberty in boys. The researchers were not entirely surprised by the findings based on previous studies that found boys were growing taller at an earlier age. “They can’t do that without entering puberty,” stated Marcia Herman-Giddens, lead researcher.

The study included 4,100 boys, aged 6 to 16 in 41 different U.S. states. While the study did not investigate possible causes of early puberty, the researchers noted, “Current environmental factors, including exposure to chemicals, changes in diet, less physical activity, and other modern lifestyle changes and exposures may be related.”

Early puberty is particularly problematic when you consider that children’s brains are not maturing at an earlier age. The combination of a body ready to reproduce with a mind that is anything but can be a dangerous one. The environmental causes of early puberty need to be found and regulated. The huge amount of chemicals we—and our vulnerable children!—are exposed to daily is sickening, literally.