A study published last year in the journal Human Reproduction found that three groups of endocrine-disrupting chemicals commonly found in personal care products, phthalates, parabens and phenols, were associated with multiple indicators of early puberty in girls but only one indicator in boys. Puberty indicators include the onset of menstruation, pubic hair growth, breast development and genital development. 

There was one type of phenol, 2,5-dichlorophenol, that was associated with later pubic hair growth in girls, however. 

This was a longitudinal study that followed 338 children from a low-income, predominantly Latino farm-working community in the Salinas Valley of California from birth to adolescence. Pregnant women were tested for the presence of personal care chemicals to determine prenatal exposure levels. Their children were later tested for the presence of the same chemicals every nine months between the ages of 9 to 13.

Exposure to endocrine-disrupting chemicals in utero and during the onset of puberty is particularly significant for reproductive development. Earlier onset of puberty is concerning because it’s associated with increased mental health problems and risk-taking behaviors, increased risk of testicular cancer in boys, and increased risk of breast and ovarian cancers in girls.

A 2008 study found that between 1940 and 1994, the age of breast development and menstrual onset trended progressively earlier for girls. Data for changes in the timing of puberty onset in boys, on the other hand, was deemed insufficient.

The current study adds to existing scientific literature suggesting that exposure to endocrine-disrupting chemicals, such as those in personal care products, may impact the timing of puberty.

Researchers noted that findings from one particular community demographic may not be applicable to the general population. They also expressed caution over the possibility that youth undergoing earlier puberty may be more likely to use personal care products, casting doubt on the direction of causality.