|"Only dull people are brilliant at breakfast"
|"The liberal soul shall be made fat, and he that watereth, shall be watered also himself."
-- Proverbs 11:25
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.
Overweight girls were more likely to have more breast development, the study showed. But Dr. Biro said he did not think weight was the whole story. He said it was possible that environmental chemicals were also playing a role, and added that he and his colleagues were now studying the girls’ hormone levels and lab tests measuring their exposures to various chemicals.
“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.”
Dr. Catherine Gordon, a pediatric endocrinologist and specialist in adolescent medicine at Children’s Hospital Boston, said that so far, most evidence showed that neither breast development nor menstrual age had changed for white girls of normal weight.
The new study included 1,239 girls ages 6 to 8 who were recruited from schools and examined at one of three sites: the Mount Sinai School of Medicine in Manhattan, Cincinnati Children’s Hospital or Kaiser Permanente Northern California/University of California, San Francisco. The group was roughly 30 percent each white, black and Hispanic, and about 5 percent Asian.
At 7 years, 10.4 percent of white, 23.4 percent of black and 14.9 percent of Hispanic girls had enough breast development to be considered at the onset of puberty.
At age 8, the figures were 18.3 percent in whites, 42.9 percent in blacks and 30.9 percent in Hispanics. The percentages for blacks and whites were even higher than those found by a 1997 study that was one of the first to suggest that puberty was occurring earlier in girls.