Whole Food mommies relax: it’s almost impossible for pee pee to turn a pool deadly.
On Wednesday, we wrote about a scientific study showing that pee in a pool’s chlorinated water can yield a toxic chemical called cyanogen chloride. That substance has recommended exposure limits from the World Health Organization and is also considered a chemical warfare agent. The yields from the pool water in the study were not anywhere near deadly or even conclusively harmful. But the next question that bubbled up in Ars readers’ minds was: How much pee would it take to develop a deadly Olympic-sized swimming pool?
As it turns out, the concentration of uric acid in pee is, to our calculation, about 112 times that of the uric acid concentration used in the experiment. If we could assume a proportional yield of cyanogen chloride just from using more uric acid, we could actually achieve toxic levels of cyanogen chloride for an Olympic pool of 10mg/L chlorinated water… for an equivalent quantity of urine. That means if each person is peeing 0.8L of the highly concentrated urine, their entire day’s yield, into this pool, you’d need about three million people peeing in that pool. If you could get at that pool without dying of either suffocation or drowning in other people’s urine, you could probably pull off death by cyanogen chloride poisoning or at least a pretty good coma.
However, there’s a problem. The researchers in the paper showed that for a concentration of 0.33 millimoles of chlorine per liter (about 15 mg/L), the dilute concentration of uric acid (5×10-5 moles per liter) eliminated all of the free chlorine. Hence, if we want chlorinated water that can actually turn all of the uric acid we’re peeing in it into cyanogen chloride, we need a more concentrated chlorinated solution.
If an approximately one-hundredth-strength-of-pee concentration of uric acid uses up 15mg/L chlorinated water, we need super chlorinated water-—on the order of 1500mg/L, or roughly half a liter of chlorine per liter of water.
In the end, we need a pool that is two parts water to one part chlorine and would probably burn the eyeballs out of your sockets and make your skin peel away from your bones (this calls for a pool boy who can only be criminally sadistic). If you and three million other people could get at this pool and unload your pee into it before your bodies melted, before the crowd crushed you to death, and before you drowned from the massive tidal wave of pee… yes, you could feasibly die of cyanogen chloride poisoning originating from chlorinated water and pee.
Of course, it is exactly this kind of risk that the EPA will insist be prevented and regulated against. Imagine if you also tossed a radioactive banana into that pool! Sheer terror at the swim club.