Everyone knows that swimming is an excellent form of aerobic exercise. It provides a strengthening, low impact workout for every muscle group. What’s more, swimming is a lifetime sport that not only evokes good memories of your childhood, but it can take you through your golden years.
However, there is a downside you may not know about. The chlorinated water in most swimming pools may be doing more than turning your hair green; it could put you at risk of illness.
It’s hard for most of us to imagine that the stuff that purifies the water in pools could actually do us grave harm, but several scientific studies have confirmed the results.
University of Illinois geneticist Michael Plewa found after conducting a 10-year study that chlorinated water—drinking water as well as in swimming pools and hot tubs—reacts with organic material and generates hundreds of different chemical compounds called “disinfection by-products” (DBPs), an unintended consequence of purification. Some of these DBPs are highly toxic, some can cause birth defects, some damage DNA, and some are cancer-causing.
Plewa said in swimming pools and hot tubs, it works this way: “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 showed higher levels of bladder cancer and asthma in people who do a lot of swimming—including professional and athletic swimmers. These individuals have greater and longer exposure to toxic chemicals that are absorbed through the skin and inhaled.
A Spanish study published Sept. 12, 2010 in the U.S. journal Environmental Health Perspectives mirrors those findings. It found the chlorine increased cancer risk and respiratory effects in a group of healthy adult swimmers.
Researchers from the Centre of Research in Environmental Epidemiology (CREAL) and Research Institute Hospital del Mar in Barcelona observed 49 healthy adults swimming 40 minutes per day in a chlorinated indoor pool had permanent mutation of the DNA, putting them at a higher cancer risk.
The researchers say they aren’t advocating for people to give up swimming, but a little personal responsibility would go along way in keeping pool water safer.
Plewa, whose study was published in the journal Mutation Research said until new technologies are engineered to safely disinfect the water in public pools, public education is needed to encourage people to bathe or shower before swimming. This simple measure would reduce the levels of dissolved organic material and would also reduce the levels of DPBs.
“It's the organic material that gets in the pool that is disinfected by the chlorine and then recirculated over and over again that causes the toxic by-products. That's why we call swimming pools DBP reactors,” he said.
Lynette Summerill is an award-winning writer who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues, she writes a blog, Nonsmoking Nation, which follows global tobacco news and events.