Puberty is arriving ever younger in American females -- 8 is no longer considered abnormal.

Excerpts courtesy of the LA Times

The first visible sign of puberty, breast budding, is arriving ever earlier in American girls.

Some parents and activists suspect environmental chemicals. Most pediatricians and endocrinologists say that, though they have suspicions about the environment, the only scientific evidence points to the obesity epidemic. What's clear, however, is that the elements of female maturity increasingly are spacing themselves out over months, even years -- and no one quite knows why according to a summary in an August 2007 report called "The Falling Age of Puberty in U.S. Girls." The report was financed by the Breast Cancer Fund, an advocacy group interested in exploring environmental causes of that disease.

Earlier breast development is now so typical that the Lawson Wilkins Pediatric Endocrine Society urged changing the definition of "normal" development. Until 10 years ago, breast development at age 8 was considered an abnormal event that should be investigated by an endocrinologist. Then a landmark study in the April 1997 journal Pediatrics written by Marcia Herman-Giddens, adjunct professor at the School of Public Health at the University of North Carolina, Chapel Hill, found that among 17,000 girls in North Carolina, almost half of African Americans and 15% of whites had begun breast development by age 8. Two years later, the society suggested changing what it considered medically normal.

The new "8" -- the medically suggested definition for abnormally early breast development -- is, the society says, 7 for white girls and 6 for African American girls.

Since the 1960s the decline in the age of maturity has crossed the line from positive reasons, such as better diet, to negative ones, such as eating too much, exercising too little and the vast unknowns of chemical pollution.

"My fear," Herman-Giddens says, "is that medical groups could take the data and say 'This is normal. We don't have to worry about it.' My feeling is that it is not normal. It's a response to an abnormal environment."

With statisticians proving that "average" is younger than recently thought, environmental activists are asking whether hormones in food, pesticides in produce or phthalates in plastics and cosmetics could be contributing to breast buds in third-graders. Overall, the biggest single factor is the trend toward obesity. Fatty tissue is a source of estrogen, so chubbier girls are exposed to more estrogen.

The biggest concern is that earlier puberty means longer lifetime exposure to estrogen, and early puberty, along with late menopause, is known to increase the risk of breast cancer.

But to design a study in which some girls are deliberately exposed to higher doses of such chemicals would be unethical.

Bonnie - I started commenting about this over 15 years ago when the changes in girls at younger ages was evident. I believe that the environment has a tremendous impact on early puberty, especially rBGH (growth hormone ), found predominately in milk. For boys, extreme environmental estrogen exposure has created development and abnormalities, as well as infertility later in life.

Bottom line, the reasons for this are man-made.