Swimming may be a great source of exercise, but new findings from Spain show that spending too much time in a chlorinated pool could increase your risk of getting cancer, Agence France-Presse reported.

Studies of a group of swimmers from indoor chlorinated pools were conducted at the Center of Research in Environmental Epidemiology (CREAL) in Barcelona and the Research Institute Hospital del Mar. Results showed changes in mutagenicity, or permanent mutation of DNA in the swimmers.

"The evidence of genotoxic effects were observed in 49 healthy adults after swimming for 40 minutes in a chlorinated indoor pool," CREAL said in a statement Monday.

Along with an increase in cancer risk, the study, published in the U.S. journal Environmental Health Perspectives, also found effects on the respiratory system.

The co-director of CREAL, Manolis Kogevinas, said the findings should not stop people from swimming, only caution them.

"The positive health impacts of swimming can be increased by reducing the levels of these chemicals," Kogevinas said.

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