Three recent studies have linked some chemicals found in pool and
spa water with cancer.
Researchers from the Barcelona-based Centre of Research in
Environmental Epidemiology (CREAL) and Research Institute Hospital
del Mar, along with a scientist from the U.S. Environmental
Protection Agency, released three papers that correlate certain
byproducts of chlorine sanitizers with bladder cancer.
The chemicals are common sanitation byproducts, and the studies
have focused on the potential health effects of their presence in
the water of indoor pool and spa facilities.
One of the papers also finds ties between regular indoor pool use
and respiratory problems. The results were headlined in a
front-page article on the popular health Website WebMD.com.
The studies make few specific recommendations for pool owners and
operators, but they tend to focus on chlorine — or, rather,
its byproducts — as the source of the problems.
“I think it’s important to differentiate the
application from the root cause,” said Ed Lightcap, a senior
account manager at DuPont Chemical in Wilmington, Del.
“Chlorine has not done humans a disservice overall;
it’s extended our longevity by killing
Though WebMD undoubtedly will increase the studies’ media
exposure, this research serves mainly to confirm existing
conclusions. “I think it’s much more confirming
that, yes, these things [can] cause problems,” Lightcap said.
“It’s expanded confirmation that these things do
The culprit in the cancer issue is the chemical compound class
called trihalomethanes, or THMs. Above certain exposure levels,
these compounds have been scientifically shown to lead to cancer in
people and animals, Lightcap said. “In humans, bladder cancer
seems to be the most common manifestation,” he noted.
Though water-transmitted THMs have been linked to bladder cancer in
previous studies, Lightcap said, “typically [it’s
discussed] in relation to shower water. Lately, some research has
been focusing on pools, too.”
Several past studies also have correlated asthmatic symptoms and
lung damage with inhalation of chloramines in indoor pool
environments. Because THMs are byproducts of chlorine
sanitization, researchers in one of the studies
determined that the presence of THMs in samples of exhaled air
indicated the presence of chloramines in those swimmers’
The scientists also tracked a certain substance in the body, known
as CC16, that can pass from the lungs into the bloodstream at a
variable rate. “The more that’s passing through the
lung membrane into the blood, the more damage to the liner of the
lungs that’s indicating,” Lightcap said.
“But to get all the way to asthma,” he added, “I
don’t know. That could be anecdotal.”
Increased lung permeability also could be explained by temporary
changes that the body’s respiratory system undergoes during
physical activity. “Oxidative stress [during exercise] will
cause damage to certain lung cells,” said Thomas Lachocki,
Ph.D., CEO of the National Swimming Pool Foundation in Colorado
Springs, Colo. “But that’s normal, and even positive in
many ways. And the body is continually repairing that
Progress in the direction of practical health solutions may be
quicker if researchers focus not only the chemical itself, but on
dosage patterns. “It isn’t chlorine,” Lightcap
said. “It’s the way chlorine is used. A well-ventilated
facility with a chlorine residual maintained around 1 ppm is
probably the best-case scenario.”
The simplest solution may be to get proactive: A well-cleaned pool
is much less likely to require higher levels of chlorine. And many
THMs can be significantly reduced by keeping water regularly
filtered or scooped for organic contaminants.
Still, it’s becoming clear that these pool-related health
concerns will not simply disappear anytime soon. “It’s
imperative that people in our industry get out ahead of it,”
Lachocki said. “It’s imperative that retailers, service
technicians, and facility operators receive verifiable training, so
they’re at least aware of these issues.”