For most of us, it's hard to imagine a girl entering puberty when she's in third or fourth grade - before she's even started Algebra. But the newest data from a study that began in 2003 was just published in Pediatrics and the findings are startling.
In 2003, 1,239 girls living in Harlem, metropolitan Cincinnati, and the San Francisco Bay area were recruited by the Breast Cancer and Environment Research Centers to participate in a longitudinal study. The girls, all between 6 and 8 years old, had physical examinations and their caregivers were interviewed and these two sets of information became the basis for the study data.
Well-established guides of puberty onset were developed collaboratively across the three study sites, including the Tanner Breast Stages, where stage 2 was determined to characterize the onset of puberty. The results varied by age, race/ethnicity, body mass index (BMI), and site. Here they are:
- At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage 2;
- At 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage 2.
These numbers represent a significant growth in the overall population of girls entering puberty earlier than those born 10 to 30 years earlier. And the most significant increase is seen among white girls. The numbers do not necessarily represent the general U.S. female population however, and researchers are now looking at the geographical factors that might influence an earlier onset of puberty.
Exposure to toxic environmental substances, such as a plasticizer known as phthalate, may act as an endocrine disruptor, encouraging early onset of puberty. Phthalate was associated in one study with intake of seafood, meat, drink, and the use of plastic cups and plastic wrap. (Chou Y.Y, published in the Journal of Pediatric Endocrinology & Metabolism.)
Obesity may be another factor in early puberty among girls; in this study, for example, high BMI was one of the correlating factors with early onset.
Yet other research is investigating the role of animal protein in the diets of toddlers and young girls, and another is investigating the role of vegetable proteins in "pubertal timing."
But whatever factors have intervened to alter the timing of this critical period in a young girl's life, the event is not like Christmas showing up early. It is indeed a very difficult time, especially for a 7 or 8 year old girl. It is associated with depression, low self-esteem, and eating disorders. Looking older than they are may cause them to act older, or invite boys and men to treat them like they are older, when, in fact, they tend to be less socially mature than their peers. Any of these factors may lead to early sexual behavior.
And then there is 'later in life," when they can look forward to a higher risk of breast cancer.
FoodConsumer.org, Medical News Today, Pediatrics