EarthTalk: I was wondering how toxic chlorine
is, because my well water was just chlorinated yesterday
and today the smell is still strong. I have a 4-year-old
daughter and I’m concerned.
—Rose Smith, via e-mail
98 percent of U.S. water treatment facilities use
chlorine to clean drinking water supplies. If your
water is from a well, there are expensive ways to
remove it close to the source, but the most affordable
approach is to filter it at the faucet or with a
to the U.S. Environmental Protection Agency (EPA), chlorine
levels of four parts per million or below in drinking water—whether
from a private well or municipal reservoir—are acceptable
from a human health standpoint. Inexpensive home drinking
water test kits (from $5 on up) that can detect levels of
chlorine and other elements in water are widely available
from online vendors. Administering the tests is easy and
can provide parents with a way to involve kids in science
for a practical purpose right at home.
was first used in drinking water to reduce waterborne infectious
diseases in Jersey City, New Jersey more than a century
ago. It was so effective at destroying potentially harmful
bacteria and viruses that the practice soon spread far and
wide. Today some 98 percent of water treatment facilities
in the U.S. use some form of chlorine to clean drinking
water supplies. The American Water Works Association (AWWA),
a trade group representing water utilities across the country,
credits the presence of chlorine in drinking water with
a 50 percent increase in life expectancy for Americans over
the last century. Indeed, some consider the chlorination
of drinking water to be one of history’s greatest
public health achievements.
others aren’t so sure that any chlorine in drinking
water should be considered safe. Opponents of chlorination
point to studies linking repeated exposure to trace amounts
of chlorine in water with higher incidences of bladder,
rectal and breast cancers. The problem lies in chlorine’s
ability to interact with organic compounds in fresh water
to create trihalomethanes (THMs), which when ingested can
encourage the growth of free radicals that can destroy or
damage vital cells in the body. Besides cancer, exposure
to THMs has been linked to other health issues including
asthma, eczema, heart disease and higher miscarriage and
birth defect rates.
with their own private wells who are skittish about chlorine
have other options for disinfecting their water. One baby
step would be to replace chlorine with chloramine, an ammonia
derivative that doesn’t dissipate into the environment
as rapidly as chlorine and has a much lower tendency to
interact in bad ways with organic compounds in the water.
However, traces of chloramine in the water may not be to
everyone’s liking either, because it causes rashes
after showering in a small percentage of people and can
apparently increase lead exposure in older homes as it leaches
the heavy metal off old pipes.
option, though somewhat costly, would be to purchase a machine
to purify the water. Ozonation units, which disinfect by
adding ozone molecules to water and leave no residues, start
at around $9,000. Another choice would be a UV light treatment
machine—at $6,000 or more—which cancels out
viruses and bacteria by passing the water through UV light
rays. The Clean Water Store is a reputable vendor and good
online source for such water treatment equipment.
the most sensible and affordable approach is to filter the
water at the faucets and taps. Carbon-based tap- or pitcher-mounted
filters can work wonders in removing impurities from drinking
water. They can even be installed on shower heads for those
with sensitive skin.
Clean Water Store.
NEW SET OF ANSWERS IS FEATURED EACH WEEK!
EarthTalk: What is the “de-extinction”
movement all about?
—Bill Mitchell, New York, NY
wooly mammoths stalk the Earth once more? If de-extinction
movement proponent and Whole Earth Catalog founder
Stewart Brand has his way, they just might.
© Royal BC Museum in Victoria
back extinct animal and plant species—is a term that
conservation biologists and environmentalists have been
bandying about for a decade or so. But only recently have
advances in genetic sequencing and molecular biology transformed
de-extinction from theory into something that we are all
likely to see in our own lifetimes.
Or so Revive
& Restore, a project of the Stewart Brand’s California-based
non-profit Long Now Foundation, likes to think. The group
is creating a movement around de-extinction, and is taking
the lead on efforts to bring back the passenger pigeon while
helping out on other ongoing efforts to restore other extinct
species including European aurochs, Pyrenean ibexes, American
chestnut trees, Tasmanian tigers, California condors, even
The main rationale behind bringing back these long gone
species and others is to preserve biodiversity and genetic
diversity, undo harm that humans have caused in the past,
restore diminished ecosystems and advance the science of
may seem only theoretical at this point, biologists are
already knocking on its door. In 2003, Spanish researchers
used frozen tissue from the last Pyrenean ibex, which had
died three years earlier, to clone a new living twin (birthed
by a goat). While the baby ibex died of respiratory failure
within 10 minutes of its birth—a common problem in
early cloning efforts—the de-extinction movement was
Restore expects to see much more progress in the coming
decade given the recent focus on the topic by geneticists,
conservation biologists and environmentalists. The group
is working with researchers around the world to put together
a list of “potentially revivable” species. Some
of the criteria for whether a given species is a good candidate
for revival include how desirable it would be to have it
around, how practical it would be to bring it back, and
whether or not “re-wilding” (returning it to
a natural environment) would be possible.
First up for
Revive & Restore is the passenger pigeon, which was
hunted from a population of billions in the 19th century
to extinction by 1914. The group has enlisted the help of
bird experts around the world to contribute to the project,
and in February 2012 convened a meeting at Harvard University
to coordinate the next steps. Currently Revive and Restore
is busy sequencing the DNA of the passenger pigeon’s
nearest living relative, the band-tailed pigeon, and is
simultaneously gathering DNA from some 1,500 preserved passenger
pigeon specimens. The group hopes to combine this biological
and genetic material to reintroduce the once abundant species.
In response to
critics who question the logic of bringing back extinct
species in a world potentially unprepared to host them,
Brand, founder of the Whole Earth Catalog, counters that
it’s our job to try to fix “the hole in nature”
we created. “It’s our fault that some of these
crucial species have been completely wiped out, so we should
dedicate our energy to bringing them back,” he says.
“It may take generations but we will get the wooly