The study released in the American Academy of Pediatrics
journal looked at the results of well-child exams of 4131 boys from 144 pediatric offices across the United States. The results were analyzed for the prevalence and mean ages of onset of sexual maturity markers.
Race seemed to play some role in the early development, with African American boys showing signs of puberty at age 9½, whereas White and Hispanic boys are entering puberty at age 10½ - 11 years-old. Previously, the average age for boys to begin entering puberty was 11 ½. Researchers, who are cautious about the findings however, say the age difference between this study and past studies could be a result of small studies and a different methodology. However, according to an Examiner
report, the study mirrors the results of a 2010 study that showed that girls are beginning to enter puberty at an earlier age as well.
Dolores J. Lamb, a molecular endocrinologist at Baylor College of Medicine and president of the American Society for Reproductive Medicine, told the New York Times
“This should perhaps set a standard going forward for being very attentive to puberty in boys and being mindful that they’re developing earlier. Whether the difference is as large as what they say on some papers 40 years ago is not clear....this is going to be incredibly useful to pediatricians and urologists.”
Although researchers did not attempt to determine the cause of the earlier development in either study, environmental factors and obesity were identified as possible causes. It has been speculated in the past that the use of hormones in the food supply may be responsible for earlier puberty. However, Stanford University pediatric endocrinology professor, Dr. Laura Bachrach, told the the New York Times
“I don’t want people to get up in arms and rush out and buy organic milk. When patients ask me, I say, ‘Do that for political reasons or because you like the taste, but don’t do it because you think it’s going to influence puberty.’”
Growth Hormones in Food
According to a Live Strong
article published in 2011, although a Cornell University study showed that research findings were mixed and limited, it did show that growth hormones used in meat and dairy products may be linked to early puberty. The Cornell University
study stated the Centers for Disease Control (CDC) conducted an investigation in Puerto Rico which found higher than normal levels of estrogen in chicken and beef which has been linked to early puberty in girls.
A University of Ottawa
study also showed that "accelerated sexual development is plausible in individuals exposed to high concentrations of estrogenic substances."
In the 80's the use of growth hormones in cattle was banned throughout much of Europe after an Italian study
showed that the hormones were linked to early puberty. The European Union banned the import of beef from the United States and Canada in the 1990's because of the prevalent use of growth hormones in cattle.
There is also a possible link between elevated hormone levels and obesity. According to a Vanderbilt University School of Medicine
study, body weight showed to be "significantly positively correlated
" with the levels of testosterone, estradiol, and estrone in individuals. A National Heart and Lung Institute
study found that high levels of hormones called androgens
, which includes male sex hormone testosterone, can be found in individuals who are obese.
The Mayo Clinic
suggests keeping children away from external sources of estrogen and testosterone as a way to possibly prevent early puberty, also known as "precocious puberty".
Estradiol and testosterone are two of the hormones banned by the European Union but are commonly used in cattle farming in the United States.
Whether hormones in the the American food supply can be directly linked to early puberty, or if obesity is the culprit is still in question among many in the medical community. The number of studies showing the possibility of a direct, or indirect link in the case of obesity, cannot be denied however.
Health Risks of Early Puberty
The CDC study showed a correlation between early puberty in girls and a higher risk for breast cancer. A Breast Cancer Fund
report also shows a link between early puberty and a higher incidence of breast cancer, along with an increased chance of developing depression and anxiety disorders. According to an Environmental Health Monthly
report, a University of North Carolina study has also found that early puberty may be linked to an increased risk of breast cancer, along with prostate cancer, infertility and, potentially, birth defects.