In swimming pools, chlorine is added for hygiene purposes -– to stop microorganisms from developing. However, when chlorine combines with urine, harmful chemicals are produced such as cyanogen chloride (CNCl) and trichloramine (NCl3), which can also be found in chemical weapons.

According to a study published in the journal Environmental Science & Technology, when uric acid in urine interacts with chlorine, “volatile disinfection byproducts” are generated, which can be hazardous to the body, Medical News Today reported.

Further research findings showed that when uric acid and other body fluids react with chlorine, toxic chemicals CNCl and NCl3 can be formed.

CNCl can cause choking and irritant symptoms, and when inhaled, the cardiovascular system, pulmonary system and the central nervous system can be affected, posing potential fatality. NCl3 is related to acute lung injury through exposure to chlorine-based disinfectants.

The researchers added that more than 90 percent of uric acid in swimming pools is human urine, and a 2009 survey in the U.S. showed that 1 in 5 American adults has urinated in a swimming pool. In 2013, Medical News Today reported a study from Centers for Disease Control and Prevention citing that E. coli is present in more than 50 percent of all public swimming pools in the U.S.

By Ha Ji-won, Intern reporter (jiwonha@heraldcorp.com)