December 20, 2018
2 min read

Chemicals used in personal care products linked to early puberty in girls

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Photo of Kim Harley
Kim G. Harley

Prenatal exposure to chemicals found in toothpaste, fragrances and makeup may cause girls to enter puberty at an earlier age, according to a study published in Human Reproduction.

“Specifically, we found that mothers who had higher levels of two chemicals in their urine during pregnancy — diethyl phthalate (which is used in fragrance) and triclosan (which is an antibacterial agent in certain toothpaste) — had daughters who entered puberty about 4 to 6 months earlier than those with low levels,” Kim G. Harley, MPH, PhD, associate professor of public health and associate director of the Center for Environmental Research and Children's Health at the University of California, Berkeley, told Infectious Diseases in Children.

“We also found that girls who had higher levels of parabens (used as preservatives in makeup and other personal care products) in their urine at age 9 also entered puberty about 6 months earlier than those with lower levels.”

Harley and colleagues used data from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) — a longitudinal birth cohort study of pesticides and other environmental exposures among children in a farmworker community — to follow 338 children (179 girls) from birth to adolescence. Pregnant women were enrolled in CHAMACOS between 1999 and 2000, and most were Latina, living below the federal poverty line and had not graduated from high school. The researchers measured concentrations of chemicals in urine collected from the mothers during pregnancy and children aged 9 years.

Harley and colleagues used Tanner staging to measure pubertal timing among the children every 9 months between the ages of 9 and 13 years.

The researchers noted an association between earlier onset of pubic hair development in girls and prenatal urinary monoethyl phthalate concentrations, and earlier menarche and prenatal triclosan and 2.4-dichlorophenol concentrations. Methyl paraben was associated with earlier breast and pubic hair development and menarche; probyl paraben was associated with earlier menarche; and 2.5 dichlorophenol was associated with later pubic hair development.

The researchers found no associations between prenatal urinary biomarker concentrations and the early onset of puberty in boys, and only one association with peripubertal concentrations: propyl paraben was linked to earlier genital development.

The study results are “important because earlier puberty in girls is associated with an increased risk for mental health and behavior problems in childhood and increased risk for breast cancer later in life,” Harley said. “These chemicals are suspected endocrine disruptors and appear to act as weak estrogens in some circumstances, which may explain why we found the associations in girls but not boys.:

Harley added that the findings are “another piece of evidence suggesting that these personal care product chemicals act as endocrine disruptors and may impact human health, so it definitely gives us cause for concern. There are steps people can take to reduce their exposure. We know that you can lower your exposure to these chemicals significantly by choosing products that are labeled as ‘phthalate free’ and ‘paraben free’ and choosing toothpaste that does not contain triclosan.” – by Bruce Thiel

Disclosures: The authors report no relevant financial disclosures.