Chemicals in cosmetics, lotions and shampoos may affect female development, according to a new study published online in the journal Environmental Health Perspectives. Researchers at Mount Sinai School of Medicine found that exposure to three common chemical classes —phenols, phthalates and phytoestrogens—disrupted the timing of puberty and could put girls at risk for health complications later in life. The study is the first to examine the effects of these chemicals on young female development.

“Research has shown that early pubertal development in girls can have adverse social and medical effects, including cancer and diabetes later in life,” said Mary Wolff, PhD, professor of Preventive Medicine and Oncological Sciences at Mount Sinai School of Medicine. “Our research shows a connection between chemicals that girls are exposed to on a daily basis and either delayed or early development.”

The research team analyzed the impact of exposure to environmental agents on 1,151 girls from New York, greater Cincinnati and northern California.

“The study measured several classes of hormone disruptors—oxybenzone, phthalates, parabens and triclosan from body care; dietary estrogens; and a phenol used in mothballs and cleaners,” said Sonya Lunder, a senior analyst for the Washington, D.C.-based Environmental Working Group. “This alone underscores the fact that pubertal girls—and the rest of us—face a barrage of hormone disrupting chemicals at a key stage of development.”

The study data showed that three classes of chemicals—phenols, phthalates and phytoestrogens—were widely detectable in the study population. High exposure to some of these chemicals was associated with early puberty. For example, the phthalates found in personal care products were related to earlier breast and pubic hair development.

But one phenol, two phytoestrogens and a subset of phthalates (those found in building products and plastic tubing) were associated with later puberty. “Enterolactone, a phytoestrogen from beans, grains flax and berries, modified the association between body mass and breast development—meaning higher BMI girls with higher enterolactone levels were less likely to have early breast development,” said Lunder.

Lunder added: “Some of the most interesting information was about the contaminant measurements themselves, which point to opportunities to identify sources and prevent exposures. Oxybenzone, the sunscreen ingredient, was much higher in white girls and all samples taken during the summer. 25DCP, a breakdown product of dichlorobenzene in mothballs and room deodorizers, was highest in black and Hispanic girls. Isoflavones from soy products were higher among Asians, while enterolactone was highest in blacks and whites.”

Although the associations between chemicals and puberty were small, the long-term impact could be significant.

“We believe that there are certain periods of vulnerability in the development of the mammary gland, and exposure to these chemicals may influence breast cancer risk in adulthood,” said Wolff. “Dietary habits may also have an impact. Further study is needed to determine how strong the link is.”