Many theories exist surrounding the increases in early puberty in young girls and boys, but while the causes are unclear, the rise in numbers is a certainty. Precocious puberty, defined as the onset of signs of puberty before ages 7 or 8 in girls and age 9 in boys, can be physically and emotionally difficult.
Puberty occurs during adolescence when children develop physically and emotionally into young men and women. Usually, this begins at approximately age 10 for girls and age 12 for boys.
A Disturbing Trend
Anecdotal evidence from parents and others in the medical community provides support for the increase in early puberty rates. Elise G. Hewitt, DC, CST, DICCP, and president of ACA’s Council on Chiropractic Pediatrics, says she sees signs of puberty among patients in her pediatric practice earlier than ever before. And research backs up this noticeable trend.
A 2010 study1 shows that girls had high rates of breast stage 2 development at ages 7 and 8 on the Tanner Scale. For example, at age 7, 23.4 percent of black non-Hispanic girls, 14.9 percent of Hispanic, and 10.4 percent of Caucasian girls had reached stage 2 on the Tanner Scale. At age 8, the rates had almost doubled. These numbers indicate increases from earlier studies. (The Tanner scale or Tanner stages is a scale of physical development. It is based on a scale of 5 progressive stages in which stage 1 is prepubertal, stage 2 is onset, and stage 5 is adult.)
The top theory among experts is that girls who have a high-fat diet and are not active or are obese are more likely to mature early. That could be the primary driver because estrogen, which triggers puberty, is stored in fat tissue. It helps explain why early puberty is more common in females than in males.
Food Supply
Another suspect in early puberty is growth hormone (GH) in the food supply. There are more chemical compounds in what we are eating and they are wreaking havoc with children’s hormonal systems.
Hormones allow for greater yields of lean muscle meat in farm animals and higher milk production, thereby feeding more people at less cost. GH is a protein hormone produced in the pituitary gland of animals, including humans, and is essential for normal growth, development, and health.
Recombinant bovine growth hormone, or rBGH (sometimes referred to as rBST, or recombinant bovine somatotropin), is used to increase milk output. It is a genetically engineered growth hormone that is banned from use in Canada, Australia, New Zealand, Japan, and all EU countries. However, in 1993, the U.S. Food and Drug Administration (FDA) approved rBGH for sale in the United States.
Better Nutrition
A June 2010 study, published in Public Health Nutrition3 in the United Kingdom, found high-meat diets in childhood are linked with early puberty for girls. The research, led by Imogen Rogers at the University of Brighton, compared the diets of 3,000 12-year-old girls at ages 3, 7, and 12.
Biro FM, et al. Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls. Pediatrics. 2010 Sep;126(3):e583-90.
Report on the Food and Drug Administration’s Review of the Safety of Recombinant Bovine Somatotropin, April 23, 2009 (This report was updated on April 23, 2009 to clarify quantities of growth hormone found in milk and those used in the 1989 rat study. www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation/ucm130321.htm.)
Rogers I, Northstone K, Dunger D, Cooper A, Ness A and Emmett P. Diet throughout childhood and age at menarche in a contemporary cohort of British girls. Pub Health Nutri. June 8, 2010; 13(12): 2052-2063.
NTP Soy Brief on Infant Formula, NTP Center for the Evaluation of Risks to Human Reproduction, National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services, Sept. 16, 2010. http://ntp.niehs.nih.gov/ntp/ohat/genistein-soy/SoyFormulaUpdt/FinalNTPBriefSoyFormula_9_20_2010.pdf
Environmental Factors
It is believed that environmental exposure to chemicals, such as pesticides and endocrine-disrupting chemicals like bisphenol A (BPA), found in plastics, also may play a role in early puberty. BPA is used primarily in the production of polycarbonate plastics and epoxy resins. These plastics are used in some food and drink containers; the resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes.
These concerns are dismissed by some. According to bisphenol-A. org, scientific evidence supports the safety of BPA and provides strong assurance there is no basis for health concerns from exposure to low doses of BPA.
But more studies need to be done. The National Toxicology Program (NTP) of the U.S. Department of Health and Human Services (HHS) in a 2008 report1 found “minimal” concern for effects on the mammary gland and an earlier age for puberty for females in fetuses, infants, and children at current human exposures to BPA. The report did conclude, however, that current human exposure to BPA is of “some concern” for effects on development of the prostate gland and brain and for behavioral effects in fetuses, infants, and children.