Young girls in America are experiencing puberty at an earlier age than biologists would particularly expect with the average age falling to ten, with black girls undergoing the process a year earlier than their peers on average, experts warn.
She found that the average age of puberty was dropping, falling to ten years old, with some girls developing as early as age six.
While there are no concrete reasons to explain what is happening, experts tell the New York Times they believe it has been caused by a combination of increasing obesity rates, the prevalence of chemicals used in plastic and the stress they are feeling in every day life.
Experts also warn that girls that undergo these early puberties are at an increased risk of developing multiple types of cancer and suffer from mental health issues like depression or anxiety.
Herma Giddens, who at the time was serving as a director of a child abuse team at Duke University – also in North Carolina – noticed that many of the children that had been abused were developing breasts as young as six or seven years old.
Young girls usually go through puberty in their early teens, with those that start showing signs of the development around age ten being considered early.
She told the Times that the number of girls that were developing quickly did not ‘seem right’. With little available data for her to investigate, she started to gather data herself.
That led to a 1997 study that changed the medical field, and the understanding doctors had about puberty in young women.
Extended research found that young girls in the U.S. were instead having puberty at around ten years old, earlier than any previous average data had shown. On average, the puberty age for young girls seemed to be moving up around three months each decade.
Black girls in particular are developing early, with the average age of puberty being found to be nine years old, according to recent studies.
This early puberty can come with serious risks as well. They are more likely to suffer breast cancer or uterine cancer later in life, other studies have found.
Rates of depression, anxiety, and other potential mental health issues are higher in girls who undergo an early puberty as well.
Discovering this phenomena was only the first step, though, as now researchers have to find out why.
While there is still no conclusive research, experts that spoke to the Times laid out three potential causes that are being investigated.
The first is obesity, a growing problem in the U.S. that has had devastating consequences for people of all ages.
Multiple studies have linked early-life obesity to an early puberty, though there is not a mechanism in places explaining this link.
‘I don’t think there’s much controversy that obesity is a major contributor to early puberty these days,’ said Dr Natalie Shaw, a pediatric endocrinologist at the National Institute of Environmental Health Sciences, told the Times, though she believes there are other factors as well.
‘Obesity can’t explain all of this…it’s just happened too quickly.’
Around one-in-five children in the U.S. aged two through 19 are obese, according to official figures, making pediatric obesity a major problem in the U.S.
Another potential factors is the prevalence of chemicals found in plastics that the young girls are being exposed to.
Phthalates are used in many plastics to make them more durable, according to the Centers for Disease Control and Prevention (CDC).
The CDC reports that the chemicals – which can be inhaled or consumed if they are contaminating food or drink – can disrupt the reproductive system of animals, though impacts on humans are unclear.
Levels of the chemicals can be found in urine samples, though, and can tell a scientist the level of exposure a person has suffered from.
Researchers have noted increased levels of the chemicals appearing in recent years, but there has yet to be a study tying them to early puberty, despite many hormone experts believing they could potentially be playing a role.
An increased amount of stress could be at play as well. Experts have already known that young girls who suffer sexual abuse are more likely to experience an early puberty.
During the pandemic, physicians also noticed an increase in reports of early puberty in young girls across the world as well – a sign that the overwhelmingly stressful period was triggering early puberty.
Similar links have also been found in girls whose parents suffer from mood disorders, or do not have a father at home – both scenarios that would likely increase daily stress levels.
While there is no concrete evidence that stress in young age can lead to early puberty, experts have long-speculated on causality.