New research reveals hidden health dangers in indoor pools

Could swimming here cause cancer?

Two reports published by the National Institute of Environmental and Health Sciences, in the journal Environmental Health Perspectives, provide deeper insight into the potential health dangers lurking in indoor pools. The reports, entitled “What’s in the Pool? A Comprehensive Identification of Disinfection By-Products and Assessment of Mutagenicity of Chlorinated and Brominated Swimming Pool Water, and “Short-Term Changes in Respiratory Biomarkers after Swimming in a Chlorinated Pool,” were published following research that was supported in part by the Environmental Protection Agency.

Findings suggest that chemicals in chlorinated pools may encourage genotoxicity, a process which damages DNA and can lead to the genetic mutations that result in cancer. The matter in question is called Disinfection By-Products [DBPs]. They form in the water of indoor pools following reactions between chlorine and “organic matter” like sweat, skin cells or urine.

Previous studies indicate that people who drank water that contained DBPs had a higher risk of bladder cancer, and reported that DBPs can be inhaled or absorbed through the skin during swimming, bathing or showering. The latest study tested water samples for the presence of DBPs and measured the sample’s mutagenicity, or the water’s likelihood to cause genetic mutations. Researchers paid close attention to the biomarkers of the study participants. Biomarkers are important in the field of cancer research: doctors often try to locate certain biomarkers within the blood to determine whether or not a specific disease is present. In this case, the researchers looked for the genotoxicity biomarker in all participants who swam in an indoor, chlorinated pool.

In 49 of the participants, these biomarkers were present after spending less than an hour in the pool. In fact, two biomarkers in particular were present: an increase in the micronuclei in blood lymphocytes, which can be an indication of cancer, and urine mutagenicity, which tells doctors that the individual has been exposed to “genotoxic agents.”

Also of note to researchers was a very small increase in a biomarker known as CC16, which indicates increased permeability in the lungs. Overall, the study revealed that there are more than one hundred DBPs present in the water of indoor pools, including some that have never been discovered before. Because the participants in the study were only measured on a short-term basis, further study of the toxicity of indoor pool water is necessary before doctors can make a solid conclusion about the connection between indoor pool water and cancer.


National Institute of Environmental and Health Science

Environmental Health Perspectives

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