Teens Before Their Time

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For that reason, he chose PCBs and DDE for one of the very few large, long-term studies of chemical exposure and puberty in humans. Rogan and his colleagues began with some 600 pregnant women, measuring concentrations of the chemicals in their bodies. When their babies were born, the researchers then measured levels in the mothers' breast milk. Finally, the team monitored the children as they grew and entered puberty.

The most prominent effect, reported last spring in the Journal of Pediatrics, was that boys exposed to DDE and girls exposed to PCBs were heavier than their unexposed peers at age 14. The study also noted an intriguing fact: girls with high prenatal PCB exposure tended to hit the first stages of puberty a bit earlier than others. Rogan stresses that the numbers were too low to be statistically significant. "If there is an effect of environmental chemicals on puberty," he says, "it's pretty small, because we studied these kids in detail over a long period of time, and we didn't see it." But, Rogan adds, "I can't rule it out."

Could other substances besides PCBs and DDE influence sexual development? Perhaps, Rogan says. But few compounds are as persistent and pervasive. Hormones given to livestock, for instance--another frequently invoked possibility--break down very quickly in the body. "I have not studied the effects of hormones in beef or dairy cattle," Rogan says. "It's not something I'm running out to study either."

What merits another look, some researchers believe, is a suite of chemicals used to make plastics. One is Bisphenol A, or BPA. Like DDE and PCBs, it is a chemical cousin of estrogen's, and it has been shown to affect the reproductive systems of lab mice. Another category of plastics ingredients, phthalates, may have played a role in a rash of cases of very early puberty in Puerto Rico back in the 1980s, with girls as young as 2 growing breasts and pubic hair. And while no cause has yet been determined, a study published last month suggests that a possible culprit could be phthalates, which are used, among other things, to make plastics flexible. It's by no means an ironclad case, however, and the plastics industry doubts that there's any link. But, says Rogan, "what went on in Puerto Rico is a good question and one that needs more study."

Then there are those who believe the sexualized messages bombarding kids from all sides could be triggering changes in the brain that are jump-starting development. Drew Pinsky, a physician and co-host of MTV's recently canceled Loveline advice program, is a proponent of this notion. "MTV," he asserts, "is absolutely one of the factors in early puberty." But even though the idea sounds nutty, says Herman-Giddens, "it would not be scientific to dismiss it. If someone cuts a nice juicy grapefruit in front of you, you salivate. Seeing things can affect us physiologically."

Whatever the cause--and it may eventually turn out to be a mix of some of or all these factors--doctors say early development has become too widespread to be treated as a medical aberration. In the past, girls who developed breasts before age 8 were often given hormone therapy to slow things down. But in a report being prepared for the Pediatric Endocrine Society, Kaplowitz and co-author Dr. Sharon Oberfield of Columbia University argue that most girls between 6 and 8 who develop breasts or pubic hair should be reclassified as normal and left untreated. "Three-, four- and five-year-old girls should still be managed aggressively," he says, "but there are far fewer of these."

That doesn't mean that breasts on seven-year-olds can simply be ignored. Mentally and emotionally, these kids are no different from their undeveloped peers. "They're not dyeing their hair purple and talking on the phone all the time," says Dr. Francine Kaufman, head of pediatric endocrinology at Childrens Hospital Los Angeles. "They're still 7."

But they don't look it, which can lead to all sorts of problems. For one thing, it makes these girls very obviously different from their peers--a position that can be deeply embarrassing for early and late developers alike. More ominously, says Susan Millstein, a professor of pediatrics at the University of California, San Francisco, "people think they're older, and the kinds of pressures put on them are more than they can handle." Marissa Carter, Sharon's mother, puts it more bluntly. "Girls who look more mature for their age are like honey," she says. "They attract older boys."

For Chicago friends Angelica Andrews, 13, and Emily Jacobson Ranalli, 12, that kind of attention is such a source of pride that the girls are willing to use their real names. Says Angelica: "The boys tease me. They ask me, 'Have you had plastic surgery?' My friends get kind of jealous." Emily, giggling, says, "I've been mistaken for 17." But even they see a downside to looking a half-decade older than they really are. "Life gets harder and harder when you're developed," admits Angelica. "Boys walk up and hit your butt. They won't stay away. They're like dogs."