What's In Your Water? Disinfectants Create Toxic By-products
In Drinking Water And Public Swimming Pools Although perhaps
the greatest public health achievement of the 20th century was
the disinfection of water, a recent study now shows that the
chemicals used to purify the water we drink and use in
swimming pools react with organic material in the water
yielding toxic consequences.
University of Illinois geneticist Michael Plewa said that
disinfection by-products (DBPs) in water are the unintended
consequence of water purification. "The reason that you and I
can go to a drinking fountain and not be fearful of getting
cholera is because we disinfect water in the United States,"
he said. "But the process of disinfecting water with chlorine
and chloramines and other types of disinfectants generates a
class of compounds in the water that are called disinfection
by-products. The disinfectant reacts with the organic material
in the water and generates hundreds of different compounds.
Some of these are toxic, some can cause birth defects, some
are genotoxic, which damage DNA, and some we know are also
carcinogenic."
The 10-year study began with an EPA grant
to develop mammalian cell lines that would be used
specifically to analyze the ability of these compounds to kill
cells, or cytotoxicity, and the ability of these emerging
disinfection by-products to cause genomic DNA damage.
"Our lab has assembled the largest
toxicological data base on these emerging new DBPs. And from
them we've made two fundamental discoveries that hopefully
will aid the U.S. EPA in their regulatory decisions. The two
discoveries are somewhat surprising," Plewa said.
The first discovery involves
iodine-containing DBPs. "You get iodine primarily from sea
water or underground aquifers that perhaps were associated
with an ancient sea bed at one time. If there is high bromine
and iodine in that water, when you disinfect these waters, you
can generate the chemical conditions necessary to produce DBPs
that have iodine atoms attached. And these are much more toxic
and genotoxic than the regulated DBPs that currently EPA
uses," he said.
Plewa said that the second discovery
concerns nitrogen-containing DBPs. "Disinfectant by-products
that have a nitrogen atom incorporated into the structure are
far more toxic and genotoxic, and some even carcinogenic, than
those DBPs that don't have nitrogen. And there are no
nitrogen-containing DBPs that are currently regulated."
In addition to drinking water DBPs, Plewa
said that swimming pools and hot tubs are DBP reactors.
"You've got all of this organic material called 'people' --
and people sweat and use sunscreen and wear cosmetics that
come off in the water. People may urinate in a public pool.
Hair falls into the water and then this water is chlorinated.
But the water is recycled again and again so the levels of
DBPs can be ten-fold higher than what you have in drinking
water."
Plewa said that studies were showing higher
levels of bladder cancer and asthma in people who do a lot of
swimming - professional swimmers as well as athletic swimmers.
These individuals have greater and longer exposure to toxic
chemicals which are absorbed through the skin and inhaled.
"The big concern that we have is babies in
public pools because young children and especially babies are
much more susceptible to DNA damage in agents because their
bodies are growing and they're replicating DNA like crazy," he
said.
Some public pools have been closed because
they have high levels of bacteria. "Public pools keep a high
level of chlorine in the water to keep bacteria and pathogens
down but very little work research is conducted on evaluating
levels of generated dangerous disinfection by-products.
"The idea is to keep the pools disinfected,
keep them in compliance, just as with drinking water but then
use engineering techniques that reduce the levels of these
toxic by-products." Plewa described another project he is
working on as a researcher with a National Science Foundation
Center called WaterCAMPWS at the University of Illinois.
"We're working with engineers and chemists to develop new
technologies that will disinfect water, that will desalinate
water, that will remove pharmaceuticals from water but in so
doing, don't generate by-products that are even more toxic
than the things you're trying to remove."
Ironically, the DBPs that are regulated by
the EPA tend to be some of the least toxic DBPs in Plewa's
study. "We've found that the emerging DBPs are much more
genotoxic and much more cytotoxic. But I can't fault EPA
because these data were not present at the time and in fact
the development of the database of over 70 DBPs has been done
in concert with our colleagues at the federal EPA."
Plewa said that until new technologies are
engineered to safely disinfect the water in public pools,
education is needed to encourage people to bathe or shower
before entering a public pool. "It's the organic material that
gets in the pool that is disinfected and then recirculated
over and over again. That's why we call swimming pools
disinfectant by-product reactors. But by public education, by
personal behavior, there should be ways that we can reduce the
levels of the dissolved organic material that should reduce
the level of DBPs."
Plewa, along with a team of scientists
received a United States Environmental Protection Agency
Science and Technology award for their paper Occurrence,
genotoxicity and carcinogenicity of regulated and emerging
disinfection by-products in drinking water: A review and
roadmap for research. It was published in the scientific
journal Mutation Research.
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