In the late 1980s, Marcia Herman-Giddens, then a physician's associate in the pediatric department of the Duke University Medical Center, started noticing that an awful lot of 8- and 9-year-olds in her clinic had sprouted pubic hair and breasts. The medical wisdom, at that time, based on a landmark 1960 study of institutionalized British children, was that puberty began, on average, for girls at age 11. But that was not what Herman-Giddens was seeing. So she started collecting data, eventually leading a study with the American Academy of Pediatrics that sampled 17,000 girls, finding that among white girls, the average age of breast budding was 9.96. Among black girls, it was 8.87. When Herman-Giddens published these numbers, in 1997 in Pediatrics, she set off a social and endocrinological firestorm. I had no idea it would be so huge," Herman-Giddens told me recently. "The Lolita syndrome" - the prurient fascination with the sexuality of young girls - "created a lot of emotional interest. As a feminist, I wish it didn't." Along with medical professionals, mothers, worried about their daughters, flocked to Herman-Giddens's slide shows, gasping as she flashed images of possible culprits: obesity, processed foods, plastics. One concern, among parents and researchers, is the effect of simultaneous exposures to many estrogen-mimics, including the compound BPA, which is ubiquitous. Ninety-three percent of Americans have traces of BPA in their bodies.