Girls Are Reaching Puberty Earlier: Should Parents Be Worried?

By Anastacia Mott Austin

A study recently commissioned by the Breast Cancer Fund in San Francisco reveals more unsettling news about the fact that girls are reaching puberty earlier than their mothers did. The report, "The Falling Age of Puberty in U.S. Girls: What We Know, What We Need to Know," was compiled by biologist Sandra Steingraber.

Why should their parents be worried? The fact that earlier puberty increases risks for several types of estrogen-dependent cancers, such as breast and ovarian cancer, is worrisome, to be sure. "The data indicates that if you get your first period before age 12, your risk of breast cancer is 50 percent higher than if you get it at age 16," said Steingraber to reporters. "For every year we could delay a girl’s first menstrual period, we could prevent thousands of breast cancers."

Also troubling is the probability that chemicals in our everyday environment, such as plastics and regular household cleaners, are at least part of the cause of disruptions to our daughters’ developing hormonal systems, especially when looked at cumulatively.

In addition, girls who reach puberty earlier than their peers face potential social embarrassment and unwanted attention, as well as a shortened childhood. Girls who reach puberty early aren’t emotionally prepared for the physical changes they are going through. "The world is not a good place for early-maturing girls," writes Steingraber. "They are at higher risk of depression, early alcohol abuse, substance abuse, early first sexual encounter and unintended pregnancies."

White girls today reach the age of menarche, or first menstruation, only slightly earlier than their mothers did, but breast-bud development (seen as the first true marker that puberty has begun) is happening up to two years earlier than it was in girls 30 years ago. For black girls, menarche is happening earlier than for whites, and the rate at which the age of puberty arrives is progressing more rapidly. In addition, the cases of precocious puberty, or significantly early development, are on the rise for both races. Girls as young as 8 years old are beginning to menstruate.

Studies have been coming in steadily over the last several years with theories as to why the phenomenon is happening. In March of this year the journal Pediatrics released a study in which rates of obesity were correlated with earlier onset of puberty. The study showed an especially strong connection between obesity in earlier childhood (ages two to five) and premature puberty – defined as the development of breast buds by age nine.

Many studies have been performed with regard to endocrine disruptors and their effects on wildlife. Bizarre stories abound of animals who developed reproductive organs of both sexes, or who reversed their sex entirely. Scientists have long been convinced that our modern environment, with its abundance of chemicals known to be endocrine disruptors, are having similar effects on humans.

In 1973, about 4,000 people in Michigan were accidentally exposed to high levels of a fire retardant containing PBBs (polubrominate biphenyls) when it was mistakenly given to dairy cattle in their feed. Years later, a study revealed that girls who had been exposed while in utero or through breastfeeding began menstruation a full year earlier than they were supposed to.

The National Institute of Environmental Health Sciences recently awarded neuroscientist Dr. Heather Patisaul a five-year grant to study the effects of exposure to Bisphenol-A (found in plastics, and a known estrogenic compound) and the age of puberty in girls.

The comprehensive new report by Steingraber looks at many of the factors examined in previous studies, such as obesity, lack of physical exercise, environmental endocrine disruptors, stress, exposure to cigarette smoke, as well as factors like premature birth, excessive television viewing, formula feeding, hormone exposure from meat and milk, and the disparities in puberty development between races.

Her conclusion is that the trend toward earlier puberty is definitely occurring, and seems to be an "ecological disorder," caused by a combination of different factors. Steingraber writes, in the overview of her report, "The evidence suggests that children’s hormonal systems are being altered by various stimuli, and that early puberty is the coincidental, non-adaptive outcome."

She is especially concerned with the regulation and public disclosure of various chemicals which are endocrine disruptors, and with ensuring that children today, regardless of gender, are given healthy choices in their diets and plenty of exercise to avoid the causative factor of obesity.

The report is the most extensive, thorough compilation of its kind of the different possible causative factors of early puberty in girls.

Dr. Marion Kavanaugh-Lynch, the director of the California Cancer Research Program in Oakland, California, is grateful for Steingraber’s work. "This is a review of what we know - it's absolutely superb," said Kavanaugh-Lynch to reporters. "Having something like this document put together that discusses all the factors that influence puberty will advance the science and allow us to think creatively about new areas of study."