Swimming pool urine-chlorine mix shown to be toxic
The uric acid in urine can generate potentially hazardous “volatile disinfection byproducts” in swimming pools by interacting with chlorine, new research shows.
The findings show definitively that uric acid from urine is “an efficient precursor to the formation of CNCl and NCl3,” says Jing Li, a visiting scholar from the China Agricultural University working at Purdue University in Indiana, US, with civil engineering professor Ernest Blatchley.
CNCl (Cyanogen chloride) is a toxic compound that affects many organs, including the lungs, heart and central nervous system by inhalation. NCl3 (Trichloramine) has been associated with acute lung injury in accidental, occupational or recreational exposures to chlorine-based disinfectants.
“Given that uric acid introduction to pools is attributable to urination, the findings indicate important benefits to pool water and air chemistry that could result from improved hygiene habits on the part of swimmers,” Blatchley says.
“A common misconception within the swimming community is that urination in pools is an acceptable practice, although signs and placards are posted in many pools to encourage proper hygiene. It is also well known that many swimmers ignore these warnings, particularly noteworthy among these are competitive swimmers.”
The new findings, which suggest more than 90 percent of uric acid introduced to pools comes from human urine, are detailed in a research paper that appeared in the journal Environmental Science & Technology. The paper was authored by Blatchley, Li and China Agricultural University researchers Lushi Lian and Yue E.
The US Centers for Disease Control and Prevention has documented cases in which people became ill after breathing contaminants at improperly maintained indoor swimming pools. Of particular concern are nitrogen-containing disinfection byproducts, which are more likely than other byproducts to be carcinogenic and to cause cell damage.