Hormone-warping chemicals found in cosmetic products could explain the ‘alarming’ trend of girls starting their periods earlier than ever before.
A US government-backed study has found that these chemicals – found in detergents, perfumes, and cosmetics – block and mimic the production of hormones responsible for the onset of puberty in girls, such as those that cause ovulation.
This would explain why the average age of puberty has decreased since the 1990s, particularly in girls rather than boys.
The chemicals are responsible for the sweet and musky smell of several perfumes, as well as found in medications for asthma and smoking cessation.
Researchers at the NIH found that chemical exposure could lead to early puberty in girls, which is increasing in the US
The findings also come as girls start wearing makeup and perfume at younger ages, with recent research finding that eight in 10 nine- to 11-year-olds in the US wearing some form of beauty product.
The researchers at the National Institutes of Health (NIH) exposed human cells grown in the lab and zebrafish to 10,000 different environmental contributors.
Zebrafish are typically used for studies like this because they share several genetic similarities to humans and other mammals.
They found that a fragrance called musk ambrette and medications called cholinergic agonists could disrupt, mimic, or block the effect of hormones.
Musk ambrette is a fragrance with a sweet, musky, and seedy smell derived from a yellow flower. Though its use is restricted in the US, it can still be found in small quantities in several perfumes sold to young girls on online marketplaces like Amazon and Etsy.
Cholinergic agonists, meanwhile, are medications used mainly to treat smoking addiction, COPD, and asthma.
‘There has been an alarming trend toward earlier puberty in girls, suggesting the influence of an environmental factor,’ the study authors wrote.
Obesity, sedentary lifestyles, and stress have all previously been touted as possible explanations.
Girls have previously told DailyMail.com that the phenomenon is not only ‘mortifying’ at school and at home, but it can also be confusing and make them miss out on vacations and other social activities.
Earlier puberty in girls has been linked to a complications like increased risk for obesity, heart disease, breast cancer, and psychological problems.
Menstruation usually starts around age 12, but study author Dr Natalie Shaw, a neuroendocrinologist at the National Institute of Environmental Health Sciences (NIEHS), said, in recent decades, girls on average have been tending towards a younger onset.
In some cases, girls as young as six have started menstruating before noticing any other signs of puberty.
Large studies in the 1990s confirmed the average age girls began developing breasts, a sign of puberty that often begins before the onset of the first period, around age ten.
This was about a year earlier than scientists previously thought, and subsequent studies have confirmed that since the 1970s, the average age of puberty onset has dropped by about three months per decade in girls.
This trend suggested that something in our environment was playing a role, study authors wrote.
To investigate this, the group of doctors from the NIEHS, an arm of the NIH, looked at a database of chemicals and prescriptions that could have an effect on hormones.
Their findings were published in the journal Endocrinology.
Doctors have not been able to identify a single or even a handful of causes for precocious puberty, though experts have told DailyMail.com that some underlying factors include obesity, stress, and genetics
Specifically, they looked at molecules called endocrine-disrupting chemicals (EDCs), substances that mimic, block, or interfere with the natural flow of hormones. These control puberty, stress, and development, according to NIEHS.
EDCs are found all over – from flame retardants to so-called forever chemicals to plastic, so the researchers included 10,000 potential targets in their research.
They narrowed in on two: musk ambrette and medications called Cholingeric agonists.
Musk ambrette has been used over the years to provide a pleasant odor to detergent, perfumes and makeup, as well as in chewing gum, candy and beverages, according to the International Agency for Research on Cancer.
It’s restricted in the US, EU and Canada. It was removed from the FDA’s list of fragrances ‘generally recognized as safe’, and in use in the country, generally.
The watchdog Environmental Working Group (EWG) states that there is ‘strong’ evidence that musk ambrette causes skin allergies.
However, the authors write, musk ambrette has still been detected in some water sources and fragrances, including several on online marketplaces like Amazon and Etsy.
Cholinergic agonists are a type of prescription drug like Chantix – which is used to stop smoking. ‘Children are less likely to encounter cholinergic agonists in their daily lives,’ the authors wrote.
However, two asthma medications called ipratropium and tiotropium are also cholinergic agonists.
When the scientists applied both of these chemicals to human cells grown in the lab and to live zebra fish, it activated cells that control puberty called musGnRh neurons.
This, they write, suggests that exposure to these EDCs could be causing the earlier onset of puberty.
‘This study suggests that, out of an abundance of caution, it is important for parents to only use personal care products for their children that are federally regulated,’ Dr Shaw said.
