Personal care products may have dangerous side effects, says new study

By Naveed Saleh, MD, MS, for MDLinx
Published May 29, 2019

Key Takeaways

Endocrine-disrupting chemicals found in personal care and consumer products—such as cosmetics, toothpaste, and hand soaps—may play a role in the advent of early puberty, particularly in girls, according to the results of a study published in Human Reproduction.

During the past 20 years, girls and possibly boys have been experiencing puberty earlier.

“Earlier age at puberty is associated with increased risk of mental health problems and risk-taking behaviors as well as increased risk of breast and ovarian cancer in girls and testicular cancer in boys,” wrote authors, led by Kim G. Harley, PhD, associate director for health effects, Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA.

“Although many factors have been promulgated to explain this phenomenon, one possible explanation is exposure to endocrine-disrupting compounds in the environment,” Dr. Harley and coauthors wrote.

For their study, they included 179 girls and 159 boys who are part of the ongoing longitudinal Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study. Concentrations of phthalates, parabens, and phenols in urine were measured in pregnant mothers and, in time, from their 9-year-old children. Researchers analyzed puberty timing every 9 months in children aged 9-13 years based on Tanner stages, which are developmental milestones reflecting changes to the breasts and genitals.

Covariates were accounted for, including mothers’ age at puberty and children’s weight. Of note, overweight girls tend to experience puberty earlier.

The following were found with respect to prepubertal exposure:

  • Higher urine levels of triclosan and 2,4-dichlorophenol in mothers during pregnancy were correlated with earlier menstrual periods in daughters. Triclosan is found in some toothpastes and hand soaps, and 2,4-dichlorophenol is derived from triclosan and found in pesticides and weed killers.
  • Increased urine levels of monoethyl phthalate in pregnant women was significantly tied to earlier pubic hair development in daughters. Monoethyl phthalate is found in fragranced personal care products.
  • No correlations were observed in sons.

The following were found with respect to peripubertal exposure.

  • At 9 years, girls with heightened urine concentrations of methyl paraben or propyl paraben experienced menstrual periods earlier than girls with lower levels. Moreover, methyl paraben was linked with earlier breast and pubic hair development. Both of these chemicals are used as preservatives in cosmetics.
  • Girls with increased urine levels of 2,5-dichlorophenol, which is found in moth balls and room deodorizers, experienced later pubic hair development.
  • Boys with increased urine levels of propyl paraben experienced earlier genital development.

To date, only a few human studies have examined the relationship between phthalates, parabens, phenols, and puberty timing, but results have been mixed. No studies have examined what occurs when children are exposed to such chemicals in utero. But in animal studies, researchers have demonstrated that prenatal and peripubertal exposures to endocrine-disrupting chemicals in cosmetics, personal care products, and scented household items can interfere with reproductive development.

“This study contributes to a growing literature that suggests that exposure to certain endocrine-disrupting chemicals may impact timing of puberty in children,” the authors concluded.

This study had certain limitations. First, the chemicals measured in urine tend to metabolize quickly, thus associations may be stronger than reported. Second, the study population consisted of Latino children in farming communities, where pesticide or other environmental exposures could be confounding results. Third, it could be that kids who go through puberty earlier use more personal care products than kids who develop more slowly.

What can be done?

“There has been increasing awareness of chemicals in personal care products and consumer demand for products with lower levels of chemicals,” Dr. Harley said.

She recommended that people who are concerned about chemicals in personal care products can check the ingredients in their products, and take practical steps to limit their exposure: “Resources like the Environmental Working Group’s Skin Deep database or the Think Dirty App can help savvy consumers reduce their exposure.”

This study was funded by the National Institute of Environmental Health Sciences and the US Environmental Protection Agency.

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