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Taking a hard look at chlorine
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| Photo by Chris Hammond Dr. Christina Bottaro |
Recent debate over contaminated drinking water and the cry to reduce greenhouse
gas emissions have helped make more people aware of the long-term effects
of environmental damage. But being aware of the problem and doing something
about it are two very different things, and it’s a distinction that
Dr. Christina Bottaro, Chemistry, knows all too well.
She has spent her entire research career working on the study of compounds
that may produce negative environmental effects. Her research focuses
specifically on the by-products that are produced from the chlorination
of waste water and drinking water.
“About 62 per cent of all by-products that are formed when you chlorinate
water with organic materials present have not been identified. Many of
those that have been identified have been found to be carcinogenic or
toxic,” pointed out Dr. Bottaro.
The fact that most Canadian municipalities use chlorine as their primary
disinfection method might cause a few people to question the reasoning.
Is this the best way of eliminating bacteria in surface water, and thus
the best way to ensure safe drinking water? And is it the most cost-effective
method? It is a fact that useing chlorine in surface waters containing
dissolved organic material results in the formation of chlorinated disinfection
by-products.
“Chlorinated compounds are formed inadvertently in the extensive
use of chlorine for disinfection of water and waste water before it is
discharged into the environment,” added Dr. Bottaro. “What people
don’t often realize is that sometimes they are forming compounds
that are potentially more destructive in the long term than the bacteria
they are trying to kill with the chlorine.”
The amount of compounds produced is positively correlated with the levels
of dissolved organic materials present in the water. These compounds may
include trihalomethanes (THM) and chlorinated carboxylic acids, substances
that have been proven to be mutagens. Prolonged exposure to these compounds
has been linked to various forms of cancer, and other health problems.
What is needed, according to Dr. Bottaro, is better analysis of these
compounds in order to gain an informed assessment and remediation of risks
associated with the use of chlorine as a disinfectant.
Other methods for eliminating bacteria during treatment include UV light
and ozone. The problem, Dr. Bottaro explains, is that once the water leaves
the plant and goes on down the line, ozone dissipates quickly and UV light
only works when it is present, therefore chlorine has to be added at some
point to prevent bacteria from flourishing. Chlorine disinfection will
unlikely be gotten rid of completely, but there are steps that can be
taken to minimize the environmental impact.
“Education is the most effective way of changing the way people look
at environmental issues,” said Dr. Bottaro. “There is little
public awareness of the long-term effects of such contamination. We need
greater understanding in order to achieve stronger regulations on water
treatment.
“There are also a lot of things going down the toilet which are known
to be bad and cause problems. Things like medications and estrogenic compounds
like birth control pills. This is creating problems in river systems as
a result. We need to paint a picture of what happens to the environment
when people do this.”
Dr. Bottaro hopes her work will shed some light on the significance of
environmental monitoring and the importance of taking a long-term view
of the issues. She has just submitted an application for a research grant
that will allow her to recreate the conventional municipal disinfection
process in her lab, and investigate the chlorinated compounds that are
formed.
“Exploitation of the environment is a global issue and we each have
to do our part to resolve it.”
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