Years later, doctors still talk about the strange case of the cows that made the children grow up too fast. The children were all girls living in or around Michigan, and all of them were born sometime after 1973. The cows were just cows--but ones that had been given very nasty feed.
Through a manufacturing error that was never quite explained, factory workers inadvertently mixed a fire retardant containing polybrominated biphenyls (PBBs) instead of a nutritional additive into animal feed. Before long, cows around the state were giving birth to stillborn calves and milk production was plummeting--but not before thousands of area residents had consumed beef or dairy products spiked with PBBs. In 2000, researchers sponsored by the National Institutes of Health caught up with daughters of women who had been pregnant or of childbearing age when they became contaminated with the toxin. They asked the daughters just one question: At what age did you begin menstruating? The answer: on average, 11.6 years old--or more than a year earlier than other girls in the area.
PBBs are known as endocrine disrupters: toxic chemicals that get inside the body and turn its hormonal systems upside down. The daughters had all likely been exposed to them either in utero or through breast milk, and the result had been a fast-forwarding of the puberty cycle, which is hard enough to manage without rushing things. The Michigan-area girls are hardly the only ones who have experienced such problems--and PBBs are hardly the only reason.
Modern parents often lament that their kids grow up too fast, but in the past generation that's been true in a whole new way, particularly for girls. It's not just the MTV airs and the world-weary mien and the too sexy outfits that kids display as a sort of rite of social passage. It's undeniable physical changes as well. Preteen girls who have not yet outgrown their Bratz and American Girl dolls are being fitted for their first bras, scrubbing away at acne, even going to school with pads in their backpacks to deal with periods that are increasingly starting in fourth grade or earlier.
This takes a toll in many ways. Bodies that grow up too fast can break down too easily. There are cancer risks that come from too much hormone dosing and skeletal problems that occur when bone growth outraces the calendar. When presexual minds find themselves in newly sexualized bodies, there is emotional damage that can be done as well--unwanted attention from boys or even men. Beyond sexual pressure, there's a simple discordance when kids look older than they feel. "I recently treated a 6-year-old who was already developing breasts and pubic hair," says Dr. Michelle Klein, a pediatric endocrinologist at Mount Sinai Medical Center and Uptown Pediatrics in New York City. "She would get into a bathing suit at camp, and the other kids would tease her. She was already a good deal taller than her peers, and adults would talk to her as if she was older and more mature--and expect more-mature behavior out of her too."
The question a growing number of parents and doctors are asking now is, How did we upset the biological balance so badly--and what can we do to set things right again?