early puberty

Arsenic exposure linked to early puberty, obesity

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Exposure to low levels of arsenic through drinking water in utero resulted in signs of early puberty and obesity as adults in female mice, according to recent findings.

“We unexpectedly found that exposure to arsenic before birth had a profound effect on onset of puberty and incidence of obesity later in life,” Humphrey Yao, PhD, a reproductive biologist at the National Institute of Environmental Health Sciences (NIEHS), said in the release. “Although these mice were exposed to arsenic only during fetal life, the impacts lingered through adulthood.”

Currently, the Environmental Protection Agency states that the maximum allowable amount for arsenic in drinking water is 10 parts per billion.

The researchers divided female mice into three groups: control (no exposure), standard exposure (current EPA guideline) or high level (42.5 parts per billion). Exposure occurred during gestation, between 10 days after fertilization and birth corresponding to the middle of the first trimester and birth in humans.

The researchers found that both the high and low doses resulted in weight gain as well as onset of puberty.

“It’s very important to study both high doses and low doses,” Linda Birnbaum, PhD, director of NIEHS and the National Toxicology program, said in the release. “Although the health effects from low doses were not as great as with extremely high doses, the low-dose effects may have been missed it only high doses were studied.”

Chemicals in Cosmetics, Soaps Tied to Early Puberty in Girls

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Girls who are exposed before birth to chemicals commonly found in toothpaste, makeup, soap and other personal care products may hit puberty earlier than their peers who aren’t exposed to these chemicals in the womb, a U.S. study suggests.

Many chemicals have been linked to early puberty in animal studies including phthalates, which are often found in scented products like perfumes, soaps and shampoos; parabens, which are used as preservatives in cosmetics; and phenols, which include triclosan, researchers note in a paper online December 3 Human Reproduction. While this is thought to interfere with sex hormones and puberty timing, few studies have explored this connection in human children.

For the current study, researchers followed 338 children from birth through adolescence. They tested mothers’ urine during pregnancy and interviewed them about potential chemical exposures, then tested childrens’ urine for chemical exposure at 9 years old and examined them for signs of puberty development every nine months between ages 9 and 13 years.

Over 90 percent of kids’ urine samples showed concentrations of all the potentially hormone-altering chemicals, except for triclosan, which was found in 73 percent of pregnant mothers’ urine samples and 69 percent of their kids’ urine samples.

For every doubling in concentration of a phthalate indicator in mothers’ urine, their daughters developed pubic hair an average of 1.3 months earlier, the study found. And with every doubling of mothers’ urine concentrations of triclosan, girls started menstruating one month earlier.

Boys’ puberty timing didn’t appear to be influenced by prenatal exposure to these chemicals.

“There has been considerable concern about why girls are entering puberty earlier and hormone disrupting chemicals like the ones in personal care products that we studied have been suggested as one possible reason,” said lead study author Kim Harley, associate director of the Center for Environmental Research and Children’s Health at the University of California, Berkeley.

Half of the girls in the study started growing pubic hair when they were at least 9.2 years old and then began menstruating when they were 10.3 years old, the study found.

Phthalates, parabens and triclosan are not banned for use in personal care products, and there isn’t solid evidence yet that they cause health effects in humans, Harley said by email.

But the current results add to increasing evidence from lab studies that suggests these chemicals can disrupt or interfere with natural hormones in the body like estrogen, Harley added.

“The fact that we find associations with earlier puberty in girls is additionally concerning,” Harley said. “The good news is, that if women want to reduce their exposure to these chemicals, there are steps they can take.”

Triclosan is no longer allowed in antibacterial soap in the U.S., but it is still in toothpaste, Harley said. Consumers should make sure it’s not a listed ingredient on any toothpaste they buy, she advised.

Parabens are also on the ingredients list, often as methyl paraben, or propyl paraben, and consumers should avoid these products, too, Harley said.

Diethyl phthalate is harder to avoid, however, because it isn’t listed on labels and is often used in fragrances, Harley said.

The study wasn’t designed to prove whether or how prenatal exposure to these chemicals might have caused early puberty. And one limitation of the study is that researchers lacked data to know if girls going through puberty might be more likely to use these personal care products, and be directly exposed that way, the study authors note.

“The effects of these chemicals are very complex,” said Dr. Luz Claudio of the Icahn School of Medicine at Mount Sinai in New York City.

“Their effects on the hormonal system is different with different chemicals, they have different potencies, their effects can be modulated by other factors such as genetic predisposition, and importantly, their effects can be different depending on the timing of the exposure,” Claudio, who wasn’t involved in the study, said by email. “With that said, this and other studies, together with the laboratory experimental evidence point to potential effects on children.”

Early Puberty May Lead to Adult Depression

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Early screening could have long-lasting psychological effects

The association between early puberty in girls and depression in adolescence is well-known, but a new study appearing in the journal Pediatrics finds that early puberty has psychological effects that last well into adulthood. In this 150 second analysis, F. Perry Wilson, MD, MSCE discusses the results which imply that earlier depression screening may be appropriate for girls who develop earlier.

Several animal studies, and basically all of human experience have taught us that puberty is a particularly difficult stage of life psychologically. A new study appearing in the journal Pediatrics now suggests that early puberty in girls can lead to depression and anti-social behavior well into adulthood, suggesting that the difficulties of those teenage years are far from fleeting.

Researchers led by Jane Mendle, MD, at Cornell used data from the National Longitudinal Study of Adolescent Health, a nationally representative survey study which ran from 1994 to 2008. More than 10,000 girls, average age 16 years, were interviewed at the start of the study and followed into their late 20’s. Over that span, they were asked about depressive and antisocial symptoms. They also reported the date of their first period, which is a proxy for pubertal development.

The average girl reported the onset of menarche at around 12 years, but there was a wide distribution, with about 10% of girls reporting a first period at age 10 or younger.

The study showed that a younger age of menarche was associated with greater depressive symptoms in the later teen years.

Perhaps more interestingly, it showed that younger age at menarche was associated with more depressive symptoms even as the women approached 30 years of age.

In an elegant analysis, the authors went on to show that the driver of that elevated depression rate in later adulthood was the depression in the teenage years. In other words, girls who develop early are more likely to get depressed as teenagers, and that depression may set the tone for decades to come.

Now there are some factors here that were unaccounted for, body weight being a major one. Overweight and obese girls go through puberty earlier, and body weight is a risk factor for depression. I asked Mendle about this potential confounder.

“We know that people treat girls who look very physically mature different from girls who do not look physically mature and that is not purely attributable to weight. We know that parents do it and we know that teachers do it. There is also not any good evidence that weight would be influencing the antisocial and externalizing behaviors that were seen”.

Clinically, whether early puberty is a sign of other stressors or a cause of distress in itself might not matter. If early puberty is associated with depression, the implication is that pediatricians should start screening for depression earlier in girls who develop earlier. The United States Preventative Services Task Force currently recommends screening for depression starting at age 12. For some girls, an even earlier intervention may have long-lasting effects.

GnRHa therapy shows no effect on final height in girls with early puberty

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In girls who experience moderately early puberty, gonadotropin-releasing human analogue treatment had no effect on final height, according to study findings published in the Journal of Clinical Research in Pediatric Endocrinology.

Şenay Sava-Erdeve, MD, faculty of medicine, department of pediatrics, division of pediatric endocrinology at Ankara University in Turkey, and colleagues evaluated 49 girls with early puberty (mean age at diagnosis, 8.65 years) to determine the effects of gonadotropin-releasing human analogue(GnRHa) treatment on final height. The mean height standard deviation (SD) score among all participants was 1.39, target height SD score was –0.22 and predicted final height SD score was –0.11.

Participants were divided into three groups: treatment group with a bone age up to 10.5 years (group 1; n = 18; mean age at diagnosis, 8.09 years), treatment group with a bone age older than 10.5 years (group 2; n = 23; mean age at diagnosis, 9.03 years) and a group in which treatment approval could not be obtained (group 3; n = 8; mean age at diagnosis, 8.83 years).

Mean height SD scores among the three groups were 0.96 for group 1, 1.78 for group 2 and 1.22 for group 3. Target height SD scores among the three groups were –0.26 for group 1, –0.4 for group 2 and 0.38 for group 3. Predicted final height SD scores were 0.08 for group 1, –0.45 for group 2 and 0.39 for group 3.

The three groups had similar final heights (P = .403), and final height was positively correlated with target height and height at diagnosis. Final height increased by 0.213 times for each 1 cm increase in height at diagnosis and by 0.459 times for each 1 cm increase in target height.

“Factors such as age at menarche and the psychological condition of the child should be considered rather than height when deciding whether to start GnRHa treatment in girls showing signs of moderately early puberty,” the researchers wrote. – by Amber Cox