IC professor writes about cancer's link to early puberty
TRUMANSBURG — American girls are going through puberty younger and younger,
putting them at higher risk for breast cancer along with learning problems and
mental health issues.
“We know that if you get your first period
before the age of 12, your risk of breast cancer is 50 percent higher than
someone who gets their period at 16,” said Sandra Steingraber, an award-winning
environmental author who teaches at Ithaca College. She formerly worked for the
Sprecher Institute for Comparative Cancer Research Program on Breast Cancer and
Environmental Risk Factors at Cornell University.
The Breast Cancer Fund published her
monograph, “The Falling Age of Puberty in U.S. Girls: What We Know, What We Need
to Know,” this month. Her new work builds on discoveries that began after she
was diagnosed with cancer when she was in college. She documented her
experiences with cancer in her book, “Living Downstream: An Ecologist Looks at
Cancer and the Environment” (1997). She also wrote “Having Faith: An Ecologist's
Journey to Motherhood” (2001), which explored fetal toxicology and genetics with
respect to her own pregnancy.
What she found in studying puberty was that
white girls' periods start at 12.6 years; for black girls, it's even earlier, at
12.1. That's a few months earlier than their mothers or grandmothers 40 years
ago, Steingraber reports.
“Early puberty is not only a women's
issue, but it is a class and race issue as well,” Steingraber said.
Girls' breast development starts one or
two years earlier than getting their periods. Half of all U.S. girls show signs
of breast development by their 10th birthday, 14 percent growing breast buds
between age 8 and 9.
Since the monograph came out and during
Breast Cancer Awareness Month, the media attention and speaking engagements have
kept Steingraber, a Trumansburg resident, busy.
“I've been riding the tiger of a lot of
media attention on it,” said Steingraber. She appeared on “Good Morning America”
a few weeks ago and had speaking engagements last week in Olympia and Seattle,
Steingraber wasn't entirely surprised to
document that puberty starts earlier. She'd been hearing stories, sometimes in
whispers from parents and had questions from family doctors about early puberty.
For instance, there was a 5-year-old girl who already had pubic hair. And she
regularly heard of third graders getting their periods. Her research was able to
back that up and pose hypotheses as to why.
The very first signs of puberty, pubic
hair, appear at about age 9 for black girls and 10 for white girls, she found.
“The childhoods of U.S. girls have been
significantly shortened,” she wrote.
In contrast, while she was exhaustively
researching the monograph, she was reading chapters of Louisa May Alcott's 1868
novel “Little Women” as a bedtime story to her daughter. The age of puberty,
according to European records, was higher back then.
She quotes the character Jo, age 15,
saying to Meg, who's 16, “Don't try to make me grow up before my time, Meg. It's
hard enough to have you change all of the sudden; let me be a little girl as
long as I can.”
“It really struck me. (Meg is) developing
breasts and dressing in more provocative ways,” she said.
There are numerous social and
psychological risks of early puberty, like earlier use of drugs, alcohol and
sexual experiences, she found.
“We've basically chopped six years out of
the childhood of our girls, and you learn better before puberty. I think there
are huge implications here,” she said.
After puberty, the brain is less plastic,
less able to learn new languages or an instrument, she said.
“Our bodies are an environment,”
In “The Falling Age of Puberty in U.S.
Girls: What We Know, What We Need to Know,” she writes that early breast
development — which is sometimes, but not always, coupled with early periods —
seems to influence breast cancer risk in and of itself.
What comes first, pubic hair or breasts,
is also a factor.
“The tempo of puberty may also affect
later breast cancer risk: A long period between breast budding and first
ovulation creates a wide ‘estrogen window' that is thought to be favorable to
the future development of breast cancer,” she writes, citing a 2004 study.
In addition, “Girls who enter puberty with
breast budding as the presenting event may be more likely to develop breast
cancer in later life than girls whose puberties manifest with pubic hair,” she
writes, citing a 2003 study.
The reasons for early puberty are not
completely clear, but Steingraber said she gleaned a variety of reasons related
to, as she calls it, “living an American lifestyle,” from dietary fat, toxins in
the environment and obesity.
Steingraber's monograph draws on
epidemiology, endocrinology, toxicology, evolutionary biology, sociology, child
development, nutrition, veterinary medicine, media studies and anthropology.
She explains the problem as ecological,
like chemicals in food and the environment that disrupt hormones.
“Certain plastics and pesticides can
signal early puberty. We also know that young girls have these chemicals in
their system because we can test them in their urine,” she said, noting that
animal evidence suggests this, too.
Various aspects of obesity — obesity
itself and hyperinsulism (insulin resistance) — appear to be factors.
“The role of obesity is strong. It's
almost certainly playing a role in the story. It's not the only factor. Lean
girls are going through puberty earlier, and even among lean black girls, black
girls are going into puberty sooner,” she said, suspecting that early puberty is
affected by some kind of endocrine disruptors.
Farmers know that heifers, young female
cattle, enter puberty earlier by being weaned, confined and put on a
It's similar with young human females,
with early weaning, too sedentary a lifestyle and junk food.
For example, formula feeding has been
linked to early puberty, she said.
She considers other environmental exposure
factors in early puberty, including high and low-level exposure to
endocrine-disrupting chemicals like cosmetics containing estrogen or
testosterone or to polybrominated biphenyls, or PBBs, used as flame retardants.
She also looks at hormones in meat and
milk and at how tobacco smoke accelerates puberty.