Team Finds Chloroform
in Indoor Swimming Pools
NEW YORK (Reuters Health) - British researchers have found very
high levels of the carcinogen chloroform and other potentially
hazardous chemicals in the water of indoor swimming pools in London,
according to a new report.
Pool water, like tap water, is very often disinfected with chlorine
to kill illness-causing microbes that lurk in the water.
Scientists have known for decades that along with the good that
comes with disinfecting water with chlorine, chemicals called
disinfection byproducts can also be formed when chlorine reacts
with organic substances like human skin and residues from body
One particular class of disinfection byproducts, termed trihalomethanes
(THMs), includes chlorinated organic chemicals like chloroform.
"Adverse reproductive outcomes such as (miscarriage), birth
weight, neural tube defects, urinary tract defects, and others
have been associated with exposure to THMs, but the evidence so
far seems to be inconsistent and inconclusive," according to Dr.
Mark J. Nieuwenhuijsen of the Royal School of Mines in London,
and colleague, H. Chu.
In their investigation, Nieuwenhuijsen and Chu tested water
samples from eight indoor swimming pools in London. A total of
44 samples were collected from the pools over a 3-week period
during the summer of 2000.
The average level of total THMs and chloroform found in the
swimming pool samples was 132 micrograms per liter and 121 micrograms
per liter, respectively. For comparison's sake, levels of chloroform
measured in tap water were found to be only 3.5 micrograms per
liter, according to the report published in the April issue of
the journal Occupational and Environmental Medicine.
Concentrations of total THMs were also correlated with the number
of people swimming in the pool and the temperature of the pool
water--higher levels were found in warmer pools with the most
While the bulk of health studies involving chlorinated disinfection
byproducts have been done with drinking water, the authors point
out that swimmers seem to have a greater risk of exposure. Aside
from ingesting the contaminated water, swimmers can breathe in
the fumes produced by the chemicals and also absorb them through
their skin, the researchers note.
"Trihalomethane concentrations should be reduced as far as possible
in swimming pools while maintaining effective control against
waterborne microbiological disease," Nieuwenhuijsen and Chu conclude.
SOURCE: Occupational and Environmental Medicine 2002;59:243-247.
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