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How to monitor urine in pools - by testing sweetness
Even though Olympic swimmers have admitted doing it, urinating in the pool is not a condoned practice. Urine contributes to the formation of compounds in pool water that can be harmful to people's health. Now scientists are tackling a new way to monitor water quality: by measuring how sweet it is. Their report appears in ACS' journal Environmental Science & Technology Letters.
Recent studies have shown that nitrogenous compounds (e.g., urea) in urine and sweat react with chlorine to form disinfection byproducts (DBPs), including trichloramine, that can cause eye irritation and respiratory problems.
Xing-Fang Li, Lindsay K. Jmaiff Blackstock and colleagues say this evidence has highlighted the need for improved understanding of pool chemistry to raise awareness and educate the public on the importance of swimming hygiene practices.
To estimate how much urine - and potentially DBPs - might be in a given pool, Li's team needed to identify what compound might consistently be present in urine. So the researchers turned to the artificial sweetener, acesulfame potassium (ACE). The sweetener, which is often used in processed foods such as fizzy drinks and baked goods, is widely consumed, chemically stable and passes right through the digestive tract and into consumers' urine.
The researchers developed a rapid, high-throughput analytical technique to test more than 250 water samples from 31 actively used pools and hot tubs in two Canadian cities, and more than 90 samples of clean tap water used to initially fill the basins.
The concentration of ACE in the pools and hot tubs ranged from 30 to 7,110 nanograms per litre of water - up to 570 times more than the levels found in the tap water samples.
Based on the concentrations of the sweetener, the researchers estimated that swimmers released more than seven gallons of urine in a 110,000-gallon pool in one instance, and nearly 20 gallons in a 220,000-gallon pool (one-third the size of an Olympic-size pool) in another instance.
The authors acknowledge funding from the Natural Sciences and Engineering Research Council of Canada.
2nd March 2017