EarthTalk: Is there any proof linking human
breast cancer to exposure to chemicals in the environment?
Or do researchers think most cases of breast cancers are
-- Bettine Carroll, New York, NY
groundbreaking research study coordinated by the non-profit
Silent Spring Institute and recently published by the American
Cancer Society found that synthetic chemicals have likely
played a large role in the rising incidence of breast cancer
throughout the world over the last half-century. The study
identified 216 man-made chemicals—including those
found in everyday products like pesticides, cosmetics, dyes,
drugs and gasoline (and diesel exhaust)—that have
been shown to cause breast cancer in animals. Researchers
believe these substances, many of which “mimic”
naturally occurring hormones once inside the body, are also
to blame for the increasing prevalence of human breast cancer.
to epidemiologist Devra Lee Davis of the University of Pittsburgh’s
Graduate School of Public Health and one of the lead researchers
on the new study, the more hormones cycling through a woman’s
body during her lifetime, the more likely she is to develop
breast cancer. Synthetic chemicals that mimic hormones magnify
the risk, as the body doesn’t know the difference
between its own real hormones and other introduced chemicals.
Only one in 10 women who develop breast cancer inherits
a defective gene from their parents, Davis adds, meaning
that in 90 percent of breast cancer cases studied, external
non-genetic agents (e.g. synthetic chemicals) contributed
to the development of the cancer.
telling clue is the fact that the breast cancer risk of
adopted children parallels the risk of the family they grew
up in, not that of their biological family, as proven by
analyzing medical records from Scandinavian countries that
keep detailed registries following people from birth to
death. “What we understand is that if cancer runs
in your family it could be because your family had similar
eating patterns, similar lifestyle patterns as well as lived
in the same area,” says Davis. “It’s really
important that we take another look at…the kinds of
chemicals that we are using everyday,” she adds. “We
think that there are alternatives that can be used.”
U.S. government has been reluctant to institute new restrictions
on the production of highly profitable synthetic chemicals,
but European regulators are taking the issue very seriously.
The European Commission’s new Registration, Evaluation,
Authorisation and Restriction of Chemicals (REACH) Program
calls on chemical manufacturers selling anywhere in Europe
to re-register and re-evaluate the potential health hazards—including
cancer risks—of their products. Environmental and
public health advocates hope that American chemical companies
will follow that lead with chemicals sold here.
the meantime, consumers can help prevent cancer by buying
and eating organic foods, avoiding pesticides and other
synthetic chemicals whenever possible, using non-plastic
containers to reheat and store foods (some plastics are
thoughts to leach cancer-causing chemicals into food when
heated), and supporting government regulation and more research
on synthetic chemicals and their effects.
Spring Institute; European
Commission’s REACH Program.
EarthTalk: What is the population status of
Africa’s large mammals, such as elephants, lions,
rhinos, and hippos? Are they all headed for extinction?
--Elias Corey, Seattle, WA
variety and abundance of wildlife in Africa, as elsewhere
around the world, is shrinking fast as human population
grows and encroaches ever more on once wild and pristine
landscapes. While illegal hunting (known in Africa as “poaching”)
still runs rampant despite government crackdowns, the spread
of logging and agriculture contributes even more to the
decline of many species of large mammals.
of the continent’s biggest mammal, the African elephant,
has declined by more than 99 percent since the 1930s, when
as many as 10 million of the great creatures roamed free
there. At last count, biologists estimated that only about
600,000 elephants are left in all of Africa.
are thriving in areas of southern Africa, thanks to massive
government conservation efforts, including a ban on the
ivory trade as part of the 144-nation strong Convention
on International Trade in Endangered Species of Wild Fauna
and Flora (CITES), which limits trade in wild animals and
their parts and accords varying degrees of protection to
more than 33,000 species of plants and wildlife.
hippopotamus population is also suffering, partly because
of the very ban on ivory. Bullied out of the ivory trade,
many African poachers have turned to hippo teeth, which
measure as long as 24 inches and have become a valuable
substitute for ivory. A 2003 census of the hippos of Virunga
National Park in the African Republic of Congo, for example,
found only 1,300 animals, down from an estimated 29,000
in a previous count three decades earlier. In neighboring
Burundi, another recent census found that two thirds of
that country’s hippo population—some 200 animals—had
disappeared in just a five-year period.
As for rhinos,
only 10,000 individuals exist around the world, down 85
percent since just 1970. Poaching has been the main culprit
in the decimation of these animals, with a single pair of
black rhino horns—coveted by Arabs in oil-rich Yemen
who collect them as symbols of wealth and status—fetching
as much as $50,000 on the black market. Of the two rhino
species in Africa, the white rhino is faring slightly better
and has rebounded from near extinction but isn’t quite
in the clear yet. The black rhino, down to only about 2,500
animals, is still considered critically endangered, however.
Where it once roamed across the entire African continent,
the black rhino is barely hanging on in just a few East
Lions may be
faring a little better, but not much. The nonprofit African
Wildlife Foundation reports that the continent’s lion
population has fallen off by half since the early 1950s
when an estimated 40,000 “kings of the jungle”
ruled. Besides contending with habitat loss to ever expanding
human settlement, Africa’s lions have also had to
deal with hunting and poisoning by livestock ranchers.
conservation efforts within Africa and internationally are
helping some of these species remain barely viable, fighting
extinction is an uphill battle, especially when expanding
human population and sputtering economies force people to
occupy previously wild lands and generate income by any
means necessary. Individuals can help by donating money
and time to organizations committed to saving these magnificent
animals. With the extinction clock ticking fast, there’s
no time to waste.
Wildlife Foundation; Convention
on International Trade in Endangered Species of Wild Fauna
and Flora (CITES).
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