Chemicals in cosmetic products that disrupt hormone balance could explain the ‘alarming’ trend of girls getting their periods earlier.
A US government study found that these chemicals, found in cleaning products, perfumes and cosmetics, block and mimic the production of hormones responsible for the onset of puberty in girls, such as the hormones that trigger ovulation.
This would explain why the average age of onset of puberty has fallen since the 1990s, especially among girls compared to boys.
These chemicals are responsible for the sweet, musky scent of various perfumes and are also used in medications for asthma and smoking cessation.
Researchers at the NIH found that chemical exposure can lead to early puberty in girls, which is becoming more common in the US
The findings also come as girls start wearing makeup and perfume at a younger age. Recent research has shown that eight out of ten nine to eleven year olds in the US who use a beauty product.
Researchers at the National Institutes of Health (NIH) exposed lab-grown human cells and zebrafish to 10,000 different environmental factors.
Zebrafish are typically used for these types of studies because they share genetic similarities with humans and other mammals.
They found that a fragrance called musk ambrette and drugs called cholinergic agonists could disrupt, mimic or block the action of hormones.
Musk ambrette is a fragrance with a sweet, musky, seedy scent, derived from a yellow flower. Although its use is limited in the US, it can still be found in small quantities in various perfumes sold to young girls on online marketplaces such as Amazon and Etsy.
Cholinergic agonists are medications primarily used to treat smoking addiction, COPD, and asthma.
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“There is an alarming trend toward earlier puberty in girls, suggesting an environmental factor,” the study authors wrote.
Obesity, a sedentary lifestyle and stress have previously been mentioned as possible explanations.
Girls previously told DailyMail.com that the phenomenon is not only “humiliating” at school and at home, but can also be confusing and cause them to miss holidays and other social activities.
Earlier puberty in girls is associated with complications such as increased risk of obesity, heart disease, breast cancer, and psychological problems.
Menstruation usually begins around age 12, but according to study author Dr. Natalie Shaw, a neuroendocrinologist at the National Institute of Environmental Health Sciences (NIEHS), girls have been starting their periods at an earlier age on average in recent decades.
In some cases, girls as young as six years old begin menstruating before other signs of puberty are visible.
Major studies in the 1990s confirmed the average age at which girls began to develop breasts, a sign of puberty that often begins before the onset of the first menstrual period, around age ten.
This was about a year earlier than scientists previously thought, and further studies have confirmed that since the 1970s, the average age of onset of puberty in girls has decreased by about three months per decade.
This trend suggests that something in our environment is at play, the study authors wrote.
To investigate, the group of doctors from the NIEHS, a part of the NIH, studied a database of chemicals and prescriptions that may affect hormones.
Their findings were published in the Endocrinology journal.
Doctors have been unable to identify a single or even a handful of causes for precocious puberty, although 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 disrupt the natural flow of hormones that control puberty, stress and development. according to NIEHS.
EDCs are everywhere: from flame retardants to so-called ‘forever chemicals’ and plastics. That’s why the researchers included 10,000 potential targets in their study.
They ultimately settled on two agents: musk ambrette and drugs called cholingeric agonists.
Musk ambrette has been used for years to give a pleasant scent to detergents, perfumes and makeup, as well as chewing gum, sweets and beverages, according to the International Agency for Research on Cancer.
It is banned in the US, EU and Canada. It has been removed from the FDA’s list of fragrances that are “generally recognized as safe” and are generally used in the country.
The watchdog Environmental Working Group (EWG) says there is “strong” evidence that musk ambrette causes skin allergies.
However, the authors write that musk ambrette has still been detected in some water sources and fragrances, including on various online marketplaces such as Amazon and Etsy.
Cholinergic agonists are a type of prescription drug, such as Chantix, that is used to help people quit smoking. “Children are less likely to encounter cholinergic agonists in their daily lives,” the authors wrote.
However, there are also two asthma drugs, ipratropium and tiotropium, that are cholinergic agonists.
When the scientists applied both chemicals to lab-grown human cells and to living zebrafish, cells that regulate puberty, called musGnRh neurons, were activated.
This, they say, suggests that exposure to these EDCs could be the cause of the earlier onset of puberty.
“This study shows that, out of sheer caution, it is important for parents to only use child care products that are federally regulated,” Dr. Shaw said.