'Precocious Puberty' Is on the Rise

Kids these days are growing up too fast -- in more ways than one. American girls are reaching puberty up to a year earlier than in previous generations, with some children showing signs of sexual development as young as age 3. In extreme cases, girls are budding breasts before they’ve even learned to read.

Researchers call this phenomenon "precocious puberty," which some say is on the rise. Forty-eight percent of African-American girls and 15 percent of Caucasian girls show physical signs of puberty by age 8, according to a study of 17,000 U.S. girls published in Pediatrics in 1997. In a subsequent study of more than 2,000 boys, lead author Marcia Herman-Giddens found that 38 percent of African-American boys and 30 percent of Caucasian boys showed signs of sexual development by age 8.

What’s going on? Although scientists have yet to prove definitive causes, many suspect that hormone-mimicking chemicals, obesity and stress all contribute to precocious puberty. The chemicals, often called endocrine disruptors, are of particular concern because they’re everywhere -- in food, water, personal-care products, some plastics and many consumer goods.

Pediatrician Darshak Sanghavi notes in The New York Times that outbreaks of precocious puberty are most often traced to accidental exposure to drugs in hormone-laden products. He describes a case in which a kindergarten-age boy and his younger sister had both begun growing pubic hair. In addition, the boy was exhibiting aggressive behaviour.

When Sanghavi's colleagues examined the children, they discovered that both had extremely elevated levels of testosterone -- equivalent to those of an adult male -- and that their father was using a concentrated testosterone skin cream "for cosmetic and sexual purposes." The children had absorbed the testosterone from normal skin contact with their father.

It’s a problem that’s not likely to go away anytime soon. The New York Times notes that prescriptions for products containing testosterone are on the rise, doubling to more than 2.4 million between 2000 and 2004.

Of course, we can’t blame it all on testosterone. Phthalates, ubiquitous industrial plasticizers common in everything from personal-care products to vinyl and plastic packaging, mimic estrogen. So do compounds in some pesticides and flame retardants. A growing body of evidence suggests that these and other endocrine-disrupting chemicals can interfere with sexual development, an idea widely introduced in the groundbreaking book "Our Stolen Future" by Theo Colburn, Diane Dumanoski, and John Peterson Myers.

In the two decades since the book’s publication, evidence has mounted that substantiates its main thesis. The September, 2006 issue of Alternative Medicine points out that a number of human studies have found possible links between endocrine disruptors and early puberty. One study found that Puerto Rican girls whose breasts developed earlier were three times more likely to have elevated levels of phthalate esters in their blood. Another reported that girls who had been accidentally exposed in the womb to polybrominated biphenyls -- common flame retardants containing compounds that mimic estrogen -- began menstruating a year earlier than a control group.

Some researchers have linked precocious puberty with factors including obesity, stress, and a sedentary lifestyle. "In the animal industry, to hasten puberty, they keep the animals confined, they feed them really rich diets, and they grow really fast," Marcia Herman-Giddens notes in Alternative Medicine. "That is exactly what we are doing to our children."

As young children struggle to cope with changing bodies, the psychological trauma can lead to later problems including depression, substance abuse and teenage pregnancies, according to a number of studies. Meanwhile, parents wrestle with painful decisions such as whether or not to give their children injections of drugs like Lupron, an expensive medication that suppresses hormones and has some 26 possible side effects.