Now Julie Beck writes that It turns out that it's a pretty bad idea, for more reasons than just the ick factor as a new study published in the American Chemical Society's journal Environmental Science & Technology, has looked at the chemistry of what happens when urine meets chlorine, and it's not pretty. When researchers mixed uric acid, found in both urine and sweat, with chlorine, they found that both trichloramine and cyanogen chloride form within an hour. "We know that there are associations between some of these chemicals and adverse human health outcomes, so we're motivated to understand the chemistry behind their formation and decay," says Ernest Blatchley III.
Exposure to trichloramine has been linked to respiratory problems (PDF), and cyanogen chloride can adversely affect the lungs, central nervous system, and cardiovascular system. Another issue is if a lot of people are peeing in the pool, there's the potential for a lot of cyanogen chloride to form, depleting the chlorine in the pool. While the cyanogen chloride would normally decay quickly, less chlorine means it might stick around longer, and that could be a real problem. All of this is to say that peeing in the pool is not harmless, despite Phelps' and Lochte's claims that it's normal and everybody does it. "There's a lot of people in the swimming community who look up to these people and listen to what they have to say," says Blatchley "[Phelps and Lochte] are not chemists and shouldn't be making statements that are that false.""