From the Chickens to the Crabs - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 62

pesticides, or industrial runoff laced with plastics. Also, a group of compounds are
known as estrogen mimics, the chemical structure of which allows them to act like
estrogen. These range from herbicides to personal-care products such as antibacterial
soap and even perfume. Indeed, so many chemicals show varying degrees of estrogenic
activity that methods to identify them are still being developed.
Estrogen is a normal hormone, but when high levels of it or estrogen mimics are
present, scientists believe that they bind to estrogen receptors on numerous cells within
the body and disrupt the endocrine system. That system of glands controls the release of
hormones and is a key regulator of growth, development, metabolism, and tissue health.
If the endocrine system is disrupted, an animal can suffer lesions, cancer, and numerous
health problems in its reproductive, immune, and nervous systems.
In 2007, in an effort to understand intersex better, a Canadian scientist named Karen
Kidd added a small amount of ethinyl estradiol, one of the active ingredients in birth
control pills, to an experimental lake in Canada. It caused the feminization of most of
the male fathead minnows in the lake. Over a number of generations, Kidd showed, the
minnows were not able to reproduce successfully, and the population was nearly wiped
out. “That was really scary,” Blazer recalled. In a 2009 study, Kidd found that once she
stopped dosing the lake with estrogen, the fathead minnow population rebounded.
“The issue is, if these chemicals are affecting the endocrine systems of fish, which are
basically the same as the endocrine system of humans, then couldn't we face some of
the same negative health effects as fish?” Blazer wondered. “I think the answer is yes, we
could.”
A growing body of evidence suggests that certain man-made chemicals released into
the water and the air have led to a surge in serious health issues, such as breast cancer,
leukemia, asthma, neurodevelopmental disorders, and physiological changes. Accord-
ing to Dr. Philip Landrigan , the chairman of the department of preventive medicine at
Mount Sinai Medical Center, in New York, the risk that a fifty-year-old white woman
will develop breast cancer has spiked from 1 percent in 1975 to 12 percent in 2009 (al-
though some of this increase is likely due to better detection). Similarly, childhood leuk-
emia is increasing by 1 percent a year, while asthma rates have trebled since 1980, and
obesity and diabetes are on the rise.
It is well documented that Western women are beginning puberty earlier and going
through menopause later. In 1800, American girls had their first period at age seven-
teen. By 1900, that had dropped to fourteen. By 2000, it was twelve. Studies have linked
early puberty to exposure to PCBs, industrial chemicals, and pesticides. Although the
evidence is not conclusive, doctors are particularly concerned about the role of endo-
crine disruptors, which may fool the body into undergoing hormonal changes early.