Ask A Scientist Chemistry Archive

name         Michael C.
status       other
age          40s

Question -   Occasionally I read health alerts regarding the failure
of EPA and Congress to clean up our rivers and reservoirs of sewage,
lawn/farm runoff.  The idea is that water utilities are forced to
chlorinate water containing organic material such as fertilizer, algae,
sediment, etc.  When Chlorine disinfects organic molecules present in
drinking water, chloroform and other compounds are formed.  Ingesting
chloroform may cause disease.  What is the difference between this idea
and ingesting chlorinated water where there is plenty of organic
molecules in the human digestive tract?  Is this type of health alert
bogus?
------------------------
Michael,

No, the cautionary is not bogus. However, there are safer ways to purify
drinking water -- bromine and ozone, for example. Neither process produces
chloroforms. Alas, both are more costly than chlorine because their
respective delivering technologies are different from that of chlorination.
For good or bad, at the bottom line is cost.

Regarding the amount of chlorine in water: As I understand the matter, water
delivered by water purification facilities is dosed with chlorine in an
amount sufficient to do the job at hand. Done properly, there should be only
a trace of chlorine in the water actually delivered to the tap.

Regards,
ProfHoff 440
==============================================================
In my opinion, the health alerts are not without concern.  There have been
reported cases where chlorinated hydrocarbons have been found in waterways
with no known source.  The supposition is that the chlorine reacts with
hydrocarbons to form the new chlorinated compounds.  There has been some
research to support this.  I drink regular tap water, and do not filter.  If I
were to use a filter, I would have an activated charcoal component to reduce
the quantity of chlorinated compounds.  Some of the compounds are identified
as known or suspected carcinogens.  I do not know how organics in the body
react to chlorine, if at all.

Pat Rowe
==============================================================
Complaints about the chlorination of drinking water drive me up onto
my "soap box".  First, chlorination of drinking water has been widely used
for about 100 years. Few chemical substances have been subjected to as large
epidemical studies as the chlorination of water. Only in the past about 30
years have analytical tools become so sensitive that it has even been
possible to detect any chlorinated organic by-products of chlorination. Yes,
there are some chlorinated by-products. But those same by-products arise
from many other sources too. Second, look at history. The number of deaths
and illnesses caused by water-borne pathogens is astronomical compared to
the number of side effects caused by chlorination of water supplies. The
chlorination of municipal water supplies is THE MOST significant advance in
public health in all of recorded history. Not even anti-biotics come even
close to the BENEFICIAL impact that chlorination of municipal water supplies
has had on public health. Third, if one is concerned about health/taste/odor
of chlorinated water there are a number of point-of-use filtration systems
that cost only about $100-$300 that will remove organo-chlorides and other
potential toxic substances of concern to some individuals.

Vince Calder
==============================================================