While some people are disgusted by the thought of human pee in their pool water, others figure there's no harm in letting loose a little urine while swimming. It turns out, however, that when urine reacts with chlorinated water, it may be creating chemical byproducts hazardous to everyone in the pool.
Cyanogen chloride (CNCl) and trichloramine (NCl3) are nitrogen-containing disinfection byproducts (N-DBPs) that are commonly found in swimming pools. In low levels, N-DBPs have been linked to eye and throat irritation, and in high levels, they have been linked to nervous and cardiovascular problems. It turns out that this toxic swimming pool environment may be caused, at least in part, by swimmers peeing in chlorinated pools.
A study authored by researchers at China Agricultural University and Purdue University and published in Environmental Science and Technology looked at the reactions between chlorinated water and uric acid and found that mixing the two produced both cyanogen chloride and trichloramine at varying levels, depending on the ratio of the precursors, the pH of the water, and the temperature of the water. They also looked at swimming pool water that already contained cyanogen chloride and trichloramine and added more uric acid, and found that the levels of cyanogen chloride increased with the addition of uric acid, although the levels of trichloramine were not so predictable. They concluded that the chlorination of uric acid may be responsible for much of the formation of cyanogen chloride in swimming pools, and perhaps, to a lesser extent, for the formation of trichloramine.
So what's the point of this wee research? Since urinating in pools is, for most swimmers, a voluntary action, perhaps encouraging swimmers to practice better urinary hygiene could improve the environment of chlorinated pools, making them a little less irritating to our various systems. Of course, this particular study only covers swimming in chlorine—you'll have to look elsewhere for verdicts on peeing in natural bodies of water.
Photo by tano_d'ere.
Volatile Disinfection Byproducts Resulting from Chlorination of Uric Acid: Implications for Swimming Pools [Environmental Science and Technology via LiveScience]