Researchers at Mount Sinai School of Medicine in New York analyzed urine samples of 1,151 girls ages 7-9 from New York, Ohio and California for three classes of chemicals -- phenols, phthalates and phytoestrogens.
The study, published in Environmental Health Perspectives, found all three chemical classes widely detectable in the girls. High exposure to one phenol, two phytoestrogens and a subset of phtalates was strongly associated with delayed puberty. However, phthalates found in personal products such as lotion and shampoo -- especially those with fragrance -- were related to earlier breast and pubic hair development.
"Our research shows a connection between chemicals that girls are exposed to on a daily basis and either delayed or early development," Dr. Mary Wolff said in a statement. "While more research is needed, these data are an important first step in continuing to evaluate the impact of these common environmental agents in putting girls at risk."
Wolff suggested certain periods of vulnerability in the development of the mammary gland and exposure to these chemicals may influence breast cancer risk in adulthood, but she noted diet may play a role as well.