A new study has found a possible explanation why girls are attaining puberty earlier. The study titled, ‘Association of phthalates, parabens and phenols found in personal care products with pubertal timing in girls and boys’, find that certain chemicals present in household shampoos, perfumes, deodorants, toothpastes, soaps etc are to blame. The study results were published in the latest issue of the journal Human Reproduction.
The team of researchers looked at the levels of chemicals such as parabens, phenols and phthalates in these household products. They report that phthalates are used increasingly in scented deodorants, shampoos, soaps, cosmetics, perfumes, nail polish etc. Parabens too are commonly used preservatives in cosmetic products and those used for personal care. They are abundantly used in soaps, shampoos, hairsprays, skin care products and lipsticks.
Personal care products. Image Credit: Gts / Shutterstock
The study was a collaboration between researchers from University of California, Berkeley along with local paediatricians and representatives of the Centers for Disease Control and Prevention (CDC).
The team looked at 179 females and 159 boys born to mothers living in California between 1999 and 2000. A total of 338 pregnant women were studied. They looked at the levels of these culprit chemicals among the mothers while they were pregnant and then again in the children when they were nine years old. The team then looked at the time of onset of puberty among the study children by following them up to the age of 13 years. Their results showed that exposure to these chemicals was directly associated with early onset of puberty among the girls but did not affect the boys. The data was a part of the US Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS).
Dr Kim Harley, associate professor in public health at the University of California, who led the study, explained that two of these chemicals were significant. She said, “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.” She added, “We also found that girls with higher levels of parabens in their bodies at the age of nine entered puberty earlier.”
Dr. Harley said that there has been a trend of girls attaining puberty earlier than before and it has been worrying. Now the cause is ascertained with this hypothesis. Early puberty could mean health issues later in life she explained. She said, “Earlier puberty in girls increases their risk of mental health problems and risk-taking behaviour as teenagers and increases their risk of breast and ovarian cancer over the long-term, so this is an important issue to address.”
The study also noted a dose-response relationship between the chemicals and the effects. They noted that when the concentration of the chemicals were doubled in the mother’s urine, there was a shift in puberty among the girl children born at a consistent rate. Authors write that these chemicals mimicked female hormones and that could be one of the reasons why boys were not found to be affected. The authors warn that this phenomenon could be linked to growing obesity rates, infertility and other population health problems. They call these chemicals “endocrine disrupters”.
The team urges precautionary measures to stop such exposure in pregnant mothers and children.