Polybrominated diphenyl ether. Wikipedia Commons By DENISE GRADY
Published: August 9, 2010

A new study finds that girls are more likely today than in the past to start developing breasts by age 7 or 8. The research is just the latest in a flood of reports over the last decade that have led to concern and heated debate about whether girls are reaching puberty earlier, and why it might be happening. Increased rates of obesity are thought to play a major role, because body fat can produce sex hormones. Some researchers also suspect that environmental chemicals that mimic the effects of estrogen may be speeding up the clock on puberty, but that idea is unproved. The issue is of concern for both medical and psychosocial reasons. Studies suggest that earlier puberty, as measured by the age at first menstruation, can slightly increase the risk of breast cancer, probably because it results in longer lifetime exposure to the hormones estrogen and progesterone, which can feed some tumors. Although the new study did not look at menstrual age, breast growth is also a sign of hormone exposure, and some researchers fear that early development might also mean an increased cancer risk. Socially and emotionally, life can be difficult for a girl who has a child’s mind in a woman’s body and is not ready to deal with sexual advances from men and boys, or cope with her own hormone-spiked emotions and sexual impulses. “Our analysis shows clearly that the white participants entered puberty earlier than we anticipated,” said Dr. Frank M. Biro, the first author of the study and the director of adolescent medicine at Cincinnati Children’s Hospital Medical Center. … “It’s certainly throwing up a warning flag,” Dr. Biro said. “I think we need to think about the stuff we’re exposing our bodies to and the bodies of our kids. This is a wake-up call, and I think we need to pay attention to it.” … 

First Signs of Puberty Seen in Younger Girls