Another possibility is that higher income girls in father-absent homes may be exposed to more artificial light which has been shown to accelerate puberty in animal studies through television, computers and other forms of technology, according to the study authors. The researchers also suggested that higher income African American girls may be more exposed to certain beauty products, such as hair straighteners, which have estrogenic properties that could influence pubertal timing.
The study adds to the debate of why girls in the United States are entering puberty at an increasingly early age. Last month, a study of 1,200 girls led by BCERC researchers at Cincinnati Children's Hospital Medical Center found that about 15 percent of the girls showed the beginnings of breast development at age 7, an increase from similar studies conducted in the 1990s.
"The hunt for an explanation to this trend is significant since girls who enter puberty earlier than their peers are not only at greater risk for reproductive cancers, they are also more likely to develop asthma and engage in higher risk sexual behaviors and substance abuse, so these studies have broader relevance to women's health," said Bay Area BCERC's principal investigator Dr. Robert Hiatt, UCSF professor and co-chair of epidemiology and biostatistics, and director of population science at the campus's Helen Diller Family Comprehensive Cancer Center.
"In some ways, our study raises more questions than it answers," said Deardorff. "It's definitely harder for people to wrap their
|Contact: Sarah Yang|
University of California -- Berkeley