A long-running study has found that chemicals commonly found in household personal care products could cause early onset of puberty in girls. These include phthalates, parabens and phenols. No similar association was found in boys.
Phthalates are used in scented products such as perfumes, deodorants, soaps, shampoo, nail polish and cosmetics; parabens are often used as preservatives in cosmetics and other personal care products; and phenols, which include triclosan and benzophenone-3, are used in soap, toothpaste, lipsticks, hairsprays, shampoos and skin lotion to increase the durability of the products.
Elaborating on the study’s findings, lead author Dr Kim Harley of University of California, Berkley said: “We found evidence that some chemicals widely used in personal care products are associated with earlier puberty in girls. Specifically, we found that mothers who had higher levels of two chemicals in their bodies during pregnancy – diethyl phthalate, which is used in fragrance, and triclosan, which is an antibacterial agent in certain soaps and toothpaste – had daughters who entered puberty earlier. We also found that girls with higher levels of parabens in their bodies at the age of nine entered puberty earlier.”
Earlier puberty in girls increases risk of mental health problems, risk-taking behaviors, breast cancer and ovarian cancer.
Harley and her colleagues analyzed data from pregnant women who enrolled in the study between 1999 and 2000. 338 of their children were followed from birth to adolescence. While the mothers were pregnant, they were interviewed at around 14 and 27 weeks’ gestation. Urine samples were also taken in order to measure concentrations of phthalates, parabens and phenols. After birth, the researchers assessed pubertal development in the 179 girls and 159 boys at the age of nine and collected urine samples. Pubertal development was checked again every nine months between the ages of 9 and 13.
It was found that increase in concentration of the aforementioned chemicals were consistently in line with earlier onset of secondary sexual characteristics. When the researchers looked at the urine samples taken from the children at the age of nine, they found that for every doubling in the concentrations of parabens, the timings of breast and pubic hair development and first menstrual period all shifted approximately one month earlier.
“This study is important because it is one of the first studies to look at human exposure in the womb and because it gives us a chance to examine exposures both in the womb and at puberty,” said Dr Harley.
However, girls who hit puberty earlier are also more likely to start using personal care products like deoderant earlier. This could be why parabens phthalate showed up in their urine.
“This is still an active area of research and more studies are needed. However, we are concerned about evidence that some widely-used chemical in the products that we put on our bodies every day may be having an impact on hormonal and reproductive development,” concluded Dr Harley.
The study was published in Human Reproduction.