By Dorsey Griffith
SACRAMENTO, Calif. — American girls are entering puberty at earlier ages, putting them at far greater risk for breast cancer later in life and for all sorts of social and emotional problems well before they reach adulthood. Girls as young as 8 increasingly are starting to menstruate, develop breasts and grow pubic and underarm hair — biological milestones that only decades ago typically occurred at 13 or older. African American girls are especially prone to early puberty.
Theories abound as to what is driving the trend, but the exact cause, or causes, are not known. A new report, commissioned by the San Francisco-based Breast Cancer Fund, has gathered heretofore disparate pieces of evidence to help explain the phenomenon — and spur efforts to help prevent it. “This is a review of what we know — it’s absolutely superb,” said Dr. Marion Kavanaugh-Lynch, an oncologist and director of the California Breast Cancer Research Program in Oakland, which directs tobacco tax proceeds to research projects. “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.”
The stakes are high: “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 the report’s author, biologist Sandra Steingraber, herself a cancer survivor. “For every year we could delay a girl’s first menstrual period, we could prevent thousands of breast cancers.”
Kavanaugh-Lynch said most breast cancer cells thrive on estrogen, and girls who menstruate early are exposed to more estrogen than normally-maturing girls. Steingraber’s paper, “The Falling Age of Puberty in U.S. Girls: What We Know, What We Need to Know,” examines everything from obesity and inactivity to family stress, media imagery and accidental exposures of girls to chemicals that can change the timing of sexual maturation. Steingraber concludes that early puberty could best be understood as an “ecological disorder,” resulting from a variety of environmental hits.
“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 writes. Steingraber’s report is being released amid growing national interest in how the environment contributes to disease, particularly cancer. California is at the forefront of the research movement. Among the ongoing efforts:
The California Environmental Contaminant Biomonitoring Program, a 5-year, state-funded project, will measure chemical exposures in blood and urine samples from more than 2,000 Californians.The Bay Area Breast Cancer and the Environment Research Center, a federally funded project run by scientists at Kaiser Permanente and the University of California, San Francisco, is studying predictors of early puberty through monitoring of environmental exposures in more than 400 Bay Area girls over several years.
For years, parents, doctors and teachers have recognized the trend in early puberty among girls, with little information to explain it. Dr. Charles Wibbelsman, a pediatrician with Kaiser Permanente in San Francisco and a member of the American Academy of Pediatrics committee on adolescents, said he now routinely sees girls as young as 8 with breast development and girls as young as 9 who have started their periods. He said the phenomenon is most striking in African American girls. “We don’t think of third graders as using tampons or wearing bras,” he said. In fact, he said, pediatricians are having to adjust the way they do regular check-ups because the older approaches don’t jibe with reality.