Science!

The age when girls hit puberty has been falling at an alarming rate for decades, and scientists have struggled to explain why. New research suggests a compound found in a wide variety of products — from cosmetics to air fresheners to detergents and soaps — may send a signal to an area of the brain that triggers the start of puberty.

It’s the first time researchers have looked at the possible impact of environmental chemicals on the brain to explain the rise in early puberty, said Dr. Natalie Shaw, a pediatric endocrinologist at the National Institute of Environmental Health Sciences in Durham, North Carolina.

Starting puberty significantly early — younger than age 8 in girls, 9 in boys — may have health effects lasting into adulthood, including higher risks of breast cancer, diabetes and heart disease. It can also lead to shortened stature in both girls and boys. In May, a study from the Harvard T.H. Chan School of Public Health found that 15.5% of girls experienced early periods — younger than age 11 — and that 1.4% started menstruating younger than age 9.

Previously, scientists have suggested possible causes including obesity, diet, socioeconomic status and potential exposure to substances such as phthalates that can disrupt sex hormones.

Shaw, a co-senior author of the new study, acknowledged a link between early puberty and excess weight in young girls. “I do think it plays a role, but in my practice, it’s not just those who are overweight or obese who are having early puberty,” she said.

While the timing of puberty may depend at least partly on genetics, a rapid change points “100% to environmental factors,” Shaw said. That’s what led the researchers to search for a compound that children might commonly be exposed to.

If Shaw and her team have found a compound that might affect when the brain sends the signal to begin puberty, they will also have discovered the mechanism at the root of the change in timing, which population studies haven’t been able to do.

Combing through 10,000 compounds in a library of licensed pharmaceuticals, environmental chemicals and dietary supplements, the researchers found several that might influence the timing of puberty. But children were most likely to be exposed to only one of them: musk ambrette, according to the report, published in Endocrinology.

Musk ambrette, a synthetic form of the fragrance, could latch onto a puberty-related receptor in the hypothalamus, which would lead to the release of GnRH, a hormone involved in the maturation of sexual organs and the production of estrogen, testosterone and progesterone.

Musk ambrette is widely used in inexpensive or counterfeit fragrances and other scented personal care products, Shaw said. But it has also turned up in surveys of wastewater and in the bodies of freshwater fish, the researchers noted.……

https://www.nbcnews.com/health/wome...emical-used-personal-care-products-rcna169967