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Scientific Method / Science & Exploration

Study finds pee in pool water yields toxic byproduct

In case you needed another reason to not urinate in the pool.

A new study on the effects of urination in chlorinated water has found that it can form two chemicals, trichloramine and cyanogen chloride, which have been associated with lung problems and can affect the heart and nervous system. In short, peeing in your pool makes negligible amounts of harmful chemicals.

The study was published in the American Chemical Society's Environmental Science and Technology journal and involved chlorinating uric acid to look at the byproducts. One of the byproducts, cyanogen chloride, can affect organs through inhalation, and the World Health Organization (WHO) recommends that its maximum concentration in drinking water should be 70 micrograms per liter or less.

Another interesting fact about cyanogen chloride: it has a military designation of CK and is considered a chemical warfare agent.

The highest concentration that the team observed was around 33 micrograms per liter at 8 milligrams per liter of chlorine—a much higher chlorine concentration than is used in the average pool—which still falls under the levels considered safe enough by the WHO. While there is no imminent threat of poisoning yourself with your own urine in the pool, the authors state that both trichloramine and cyanogen chloride are "volatile" and "have the potential to adversely affect air and water quality in chlorinated, indoor pools." They further note that since peeing in a pool is a voluntary process, "opportunities exist for significant improvement of air and water quality… via changes in swimmer hygiene practices."

The study was sponsored in part by the National Swimming Pool Foundation, which offers certifications for pool and spa technicians.

DOI: 10.1021/es405402r, Environmental Science and Technology.

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120 Reader Comments

  1. The dreaded Warm Spot of Doom just got a little doomier.
    9952 posts | registered
  2. Note to self: Don't swallow pool water?
    3615 posts | registered
  3. I suspect this will only encourage some folks rather than what we'd hope for.
    10403 posts | registered
  4. Quote:
    They further note that since peeing in a pool is a voluntary process, "opportunities exist for significant improvement of air and water quality… via changes in swimmer hygiene practices."


    I am going to presume majority of people peeing in pool is children or toddlers and so is more or less an involuntary process... But I have lost faith in humanity before on more concerning matters.
    493 posts | registered
  5. Chlorine was a chemical warfare agent too, and we dump that in pool water all of the time.
    4866 posts | registered
  6. Given there are alternatives to chlorine for pools, such as salt water, how do they fair in a public pool environment?
    1451 posts | registered
  7. I was on a swim team for 10 years when I was a kid. Based on this article, I shudder to think about how much toxic waste I swam through during that time. Blecch.
    9 posts | registered
  8. Did they just discover cooties?
    117 posts | registered
  9. Ahhhhhhhhh


    What?
    757 posts | registered
  10. Still not as bad as finding the dreaded "Babe Ruth" candy bar floating in your pool.

    :D
    907 posts | registered
  11. Rabbiddog wrote:
    Still not as bad as finding the dreaded "Babe Ruth" candy bar floating in your pool.

    :D


    Image
    757 posts | registered
  12. Ah, Casey drew the wrong end of the pee stick. Was this article needed?
    66 posts | registered
  13. Oh dear...if only I read this article 30 minutes sooner.
    738 posts | registered
  14. ajmas, in our case, the salt is only added to the water so that a catalyst system can convert it into free chlorine. It's done because the system can keep the free chlorine at a level to keep the pool disinfected without any intervention, and in the long run at lower cost. I don't think that salt by itself disinfects water until you get to levels like in the dead sea - after all, the oceans are salty, but teaming with life!

    In public pools in the UK, they sometimes use bromine products instead of chlorine, and also add a chemical that changes colour if someone pees in the pool. The offending person is then thrown out while everyone laughs at them, and not permitted back in the pool.
    15 posts | registered
  15. I'm still waiting for the prophesized 'chemical that colors the water upon contact with pee' before I enter a pool again.

    Also, I'd like to change that sign to:

    "Welcome to our L

    There's no POO in it
    Keep it that way"
    286 posts | registered
  16. Rabbiddog wrote:
    Still not as bad as finding the dreaded "Babe Ruth" candy bar floating in your pool.

    :D


    Yes, it's very shocking to find a dead baseball player floating in your pool :-)
    2336 posts | registered
  17. urea reacts with hypochlorite to produce hydrazine, through peeing in the pool and excretion through the skin. exposure is low, but its good to know you make your own rocket fuel whenever you have a dip
    42 posts | registered
  18. Gives new meaning to 'Cyanogen Mod'
    2336 posts | registered
  19. The safety of peeing in the pool has been thoroughly tested since the invention of the first swimming pool. Did we really need a study to figure out if it wouldn't poison us? But at least now, anyone with a desire to create deadly chemical agent has some new territory to investigate.
    549 posts | registered
  20. Considering the concentrations they found were less than half the limit and that was when they had far more chlorine in the water that a typical pool, isn't the headline just a little sensationalist?
    1644 posts | registered
  21. fraoch wrote:
    urea reacts with hypochlorite to produce hydrazine, through peeing in the pool and excretion through the skin. exposure is low, but its good to know you make your own rocket fuel whenever you have a dip


    No one should try to make their own hydrazine unless they want to end up in the Darwin Awards.
    549 posts | registered
  22. mattclary wrote:
    The safety of peeing in the pool has been thoroughly tested since the invention of the first swimming pool.

    No, it has not, because the chemicals used to treat pool water and the practices surrounding using them have not been consistent over time. (They're not even really consistent today.)
    615 posts | registered
  23. The thought is unpleasant, but there really isn't much objective reason to being bothered by swimming through low concentrations of pee. The ocean is much more disgusting, and most of us don't blink before swimming in it. For that matter, much of the water molecules we drink have passed through countless urethras since their formation.
    165 posts | registered
  24. This shi pee just got real!
    13758 posts | registered
  25. Johnny! Stop peeing in the pool! But, everyone pees in the pool. Yeah, but not from the high diving board!
    7 posts | registered
  26. sbol wrote:
    For that matter, much of the water molecules we drink have passed through countless urethras since their formation.


    And Oddest Sentence of the Week Award goes to...
    196 posts | registered
  27. As someone who swam and played water polo college and still competes... let's just say there are times that anyone who is squeemish about pee will not want to be remotely near a pool. Namely, after warm ups for any big meet.
    67 posts | registered
  28. guifa wrote:
    As someone who swam and played water polo college and still competes... let's just say there are times that anyone who is squeemish about pee will not want to be remotely near a pool. Namely, after warm ups for any big meet.

    And now we know why they're called warm-ups!
    9952 posts | registered
  29. sbol wrote:
    The thought is unpleasant, but there really isn't much objective reason to being bothered by swimming through low concentrations of pee. The ocean is much more disgusting, and most of us don't blink before swimming in it. For that matter, much of the water molecules we drink have passed through countless urethras since their formation.



    Oh I think about it, especially when I see dead fish floating at the top.*

    *And I haven't even farted.
    13799 posts | registered
  30. They basically found that over-chlorinated pools produce negligible amounts of CK, which is considered a "chemical warfare agent"..

    NEWS ALERT!!!!

    Chlorine is also considered a "chemical warfare agent"!
    841 posts | registered
  31. In public pools in the UK, they sometimes use bromine products instead of chlorine, and also add a chemical that changes colour if someone pees in the pool. The offending person is then thrown out while everyone laughs at them, and not permitted back in the pool.


    I am pretty sure that is an urban legend. Also, the active ingredient in urine (urea) is also produced in sweat, which people do in the pool all the time.

    ah yes, here it is:

    http://www.snopes.com/science/poolpiss.asp
    3353 posts | registered
  32. sbol wrote:
    For that matter, much of the water molecules we drink have passed through countless urethras since their formation.


    And Oddest Sentence of the Week Award goes to...


    Required citation: http://what-if.xkcd.com/74/
    20 posts | registered
  33. Isn't most tap water chlorinated? Doesn't this also mean that these toxic chemicals would be found in your toilet?
    39 posts | registered
  34. Pure FUD. Chlorinated swimming pools are safe.

    In Thailand, I saw people defecating in a river 30 feet upstream of other people brushing their teeth.
    Now that gave me chills…. :(
    1703 posts | registered
  35. ajmas, in our case, the salt is only added to the water so that a catalyst system can convert it into free chlorine. It's done because the system can keep the free chlorine at a level to keep the pool disinfected without any intervention, and in the long run at lower cost.

    While salt is cheaper than chlorine, the systems are rather expensive, have an expensive part that requires replacement every 3-5 years, and they produce a significant amount of sodium hydroxide that must be offset with additional acid on a regular basis, negating some of the "lower maintenance" advantage. They're closer to a wash than I had hoped they'd be.
    4687 posts | registered
  36. And this is why I come read Ars every day. This isn't just about iphones and androids - in one day we get the real story of people peeing in pools, and the effects of Cuckoo bird poop of other predators!
    108 posts | registered
  37. So, exactly how much urine needs to be added to a pool to cause a toxic event? An olympic sized pool holds 2.5 million litres of water. Aproperly maintained pool has at max 4ppm chlorine in it. So you are looking at around 10kg of liquid chlorine to properly maintain the pool.

    What are the chances of this actually happening?
    1341 posts | registered
  38. I know. I swim 4 times a week, about 2000-3000 yards each.

    The pool I swim at is adults only, lap swim only, thankfully. Some swimmers pee I nthe pool. But nothing compared to what hordes of kids may do.

    I briefly swam at a little 25y pool near my house a few years ago. The lap swim time was right after little kids splash time. I could smell the byproducts of kid pee and chlorine in the water. Really objectionable rotten eggs smell. And I got two really nasty sinus infections back to back in the short time I swam there. Never had anything like that, before or since.
    17572 posts | registered
  39. I've been to a few pools that use that 'super wonderful' additive that changes the colour of the water when it interacts with pee. While it may make me a very bad person, watching a trail of purple water chase a small child has had me laughing my ass off on more than one occasion.
    3357 posts | registered

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