NEW YORK (Reuters Health) - Girls exposed to chemicals commonly used in toothpaste, cosmetics, soaps and other personal care products may reach their counterparts who do not.
Animal studies have linked early puberty with many chemicals, including phthalates, usually found in products that smell like perfume, soap and shampoo, as well as parabens, which are used as preservatives in cosmetics and triclosan, researchers in the journal Human Reproduction have reported.
Although scientists have found that these substances affect sex hormones and adulthood, few studies have explored this relationship in humans.
For the study, researchers followed 338 children from birth to adolescence. They analyzed mothers' urine during pregnancy and interviewed them about their potential exposure to chemicals.
The researchers then analyzed children's urine to monitor exposure to chemicals at the age of nine, and examined children for signs of puberty every nine months between the ages of 9 and 13.
More than 90 percent of children's urine samples showed concentrations of all chemicals that could cause hormonal changes.
The study found that each increase in the concentration of phthalates in the mother's urine led to the growth of pubic hair in their daughters 1.3 months earlier than usual.
However, the attainment of males did not appear to be affected by the exposure of parents to these chemicals.
The study found that pubic hair began to grow in half of girls when they were at least 9.2 years old and began menstruating when they were 10.3 years old.
Kim Harley, a senior researcher at the Center for Environmental Research and Child Health at the University of California at Berkeley, said phthalates, shampoos and treaclosan were not banned in personal care products and there was little evidence of harm to human health.
The latest findings add to growing evidence from scientific studies that these substances can cause and affect the body's natural hormones such as estrogen.
"The discovery of their association with early puberty in girls is worrying, but if women want to limit their exposure to these chemicals, there are steps they can take," she said.
Harley recommended consumers make sure that triclosan is not a component of any toothpaste before buying. Paraben was also included in the list of ingredients in the form of methyl paraben or propylparaben, and consumers should ensure that the products were free of these substances as well.
