It’s almost summer! Time for a giant bath of tepid, watery piss

posted in: General science | 0

Introduction:

we don't swim in your toilet, don't pee in our pool
Figure 1: A common sign that pool owners are forced to display. Please, we’re all begging you, stop peeing! Licence: CC2.0.

Summer is almost here.  Time to learn about what we’re going to be cooling off in.

Everyone knows that there’s some piss in most swimming pools.  But it’s hard to quantify how much.  Recently a group of researchers came up with a clever new way of measuring just how much piss we wade through when we dive into a pool.  I’d like to say that the results were shocking, but I’ve seen that all-too telling, satisfied look on too many faces.

Background:

Pissn’ in a pool is more than just a cultural faux pas (Figure 1).  It’s a legitimate health concern.

Urine contains nitrogenous compounds that react with the disinfectants in pool water.  These reactions can form disinfection byproducts, which contain mutagenic organics that you don’t want to have splashed into your mouth (Daiber et al., 2016).

Unfortunately, it’s difficult to quantify just how much piss, or other bodily fluids have been added to a pool of disinfected water.  (Although, I must add, it is a very good thing that the water is disinfected!)  And there is no way to see if or when a person has urinated in a pool.  (Other than the telling, satisfied look on their face.)

Discussion of the new study:

A new study by Jmaiff Blackstock et al. (2017) has managed to measure the amount of urine in swimming pools and hot tubs.  The genius of this research was identifying a proxy for swimmers’ piss.  A marker that doesn’t react and chemically change with the disinfected pool water.  What did they measure?  An artificial sweetener called acesulfame-K.

The artificial sweetener acesulfame-K was measured because it’s not metabolized by humans.  Whatever we consume is all pissed out later.  The researchers used the average concentration of acesulfame-K in human piss (which was measured by a previous study) to estimate the amount of urine in each pool they examined.

A Google Maps image of a public pool that looks alarmingly like a gigantic toilet.
Figure 2: A Google Maps image of a public pool that looks alarmingly like a gigantic toilet.

Acesulfame-K was found in every sample they analyzed.  Yep, every pool they looked at (250 samples) contained some human piss.  They concluded that in a 110,000-gallon (US) pool, there’s about 30 liters of piss.  We’re all swimming around in gigantic, watery toilets (Figure 2).

110,000 US gallons is about 416,395 liters.  So the piss to water ratio is approximately 30:400,000 or 3:40,000.  So this is about ~1:13,333.

Conclusion:

Scientists have trained their minds to search for solutions to problems.  In this example, researchers have identified a clever marker for a public health issue that was previously difficult to measure.

This resulted in identifying the ratio of piss to water in a swimming pool (1:13,333).  By the way, this is far higher than my preferred ratio of none:all.

References:

Daiber, E. J., DeMarini, D. M., Ravuri, S. A., Liberatore, H. K., Cuthbertson, A. A., Thompson-Klemish, A., … & Richardson, S. D. (2016). Progressive Increase in Disinfection Byproducts and Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact of Human Inputs. Environmental science & technology, 50(13), 6652-6662. http://pubs.acs.org/doi/abs/10.1021/acs.est.6b00808

Jmaiff Blackstock, L. K., Wang, W., Vemula, S., Jaeger, B. T., & Li, X. F. (2017). Sweetened swimming pools and hot tubs. Environmental Science & Technology Letters, 4(4), 149-153. http://pubs.acs.org/doi/pdf/10.1021/acs.estlett.7b00043

Jared Peters

Jared Peters

Jared Peters, PhD, is a geoscientist who specialises in marine sedimentology, marine palaeoglaciology and climate change.
Jared Peters
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Jared Peters, PhD, is a geoscientist who specialises in marine sedimentology, marine palaeoglaciology and climate change.