Is That Pool Really Sanitary? New Chemical Approach Has Answers
Checking for levels a common sweetener is one way to see how clean and healthy a pool is
Scientists find that testing pool water for a common artificial sweetener is one way to check the hygiene level of the pool.
An artificial sweetener found in more than 4,000 foods, beverages and pharmaceutical products turns up in swimming pools in unusually high concentrations.
That’s intriguing until you learn how it gets there. Then it’s just gross.
“It’s evidence people are peeing in pools,” said Lindsay Blackstock, a doctoral student in analytical and environmental toxicology at the University of Alberta, Canada.
Mrs. Blackstock and several colleagues tested 31 swimming pools and hot tubs in hotels and recreational facilities in Canada for the presence of acesulfame potassium, an artificial sweetener that is largely undigested and almost entirely excreted in urine.
There’s an ick factor to swimming in a pee-tainted pool, but the real concern is what happens chemically. Urine combines with chlorine to create byproducts that irritate the eyes and respiratory system, and the spent chlorine is no longer available to kill disease-causing germs.
Pool operators continually replenish chlorine to keep the water safe, but tests like Mrs. Blackstock’s help them figure out what substances are affecting the chemistry.
Sold under the brand name Sunett, acesulfame potassium is 200 times sweeter than sugar and represents 8% of the global high-intensity sweeteners market, according to Sergey Gudoshnikov, a senior economist with the International Sugar Organization.
It’s used in products including baked goods, frozen desserts, chewing gum, diet sodas, sport drinks, fruit juices, toothpaste, mouthwash, breakfast cereals, condiments, snack foods, soups, cough syrups, jams and jellies.
Mrs. Blackstock and her colleagues were inspired to look for acesulfame potassium in pool water because it is also used as a proxy to estimate the impact of human waste on groundwater, lakes and rivers.
They found it in all of their pool and hot-tub samples, and in far greater concentrations than in the water sources used to fill them. “We saw an increase of four times greater and up to 570 times greater in recreational water samples compared to tap water samples,” Mrs. Blackstock said.
The researchers also measured the amount of ACE-K, as it’s known for short, in urine samples from 20 Canadians to arrive at a rough estimate of the normal concentration in the general population.
Using that information, they deduced that a 110,000-gallon pool they studied contained an estimated eight gallons of urine, while a 220,000-gallon pool contained an estimated 20 gallons. The concentrations represented about 0.01% of the total water volume.
“If your eyes are turning red when you’re swimming, or if you’re coughing or have a runny nose, it’s likely there is at least some urine in the pool,” said Michele Hlavsa, chief of the Healthy Swimming Program for the Centers for Disease Control and Prevention.
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Urine isn’t a primary source of germs in pools or hot tubs, but feces that clings to the body is. At any time, Dr. Hlavsa said, adults have about 0.14 grams of poop on their bottoms and children have as much as 10 grams.
“When you’re talking about bigger water parks with 1,000 children in a given day, you’re now talking about 10 kilograms or 22 pounds of poop,” she said.
Feces can contain bacteria, viruses and parasites such as E. coli, norovirus and giardia that can lead to outbreaks of diarrhea, vomiting and other illnesses.
In 2011 and 2012, the most recent data available, the CDC recorded at least 185 illnesses stemming from exposure to these or similar organisms in pools, hot tubs and spas. Nearly 900 more cases were attributed to a chlorine-resistant parasite known as cryptosporidium.
“We’re not so worried about pee,” Dr. Hlavsa said. “We’re worried it will use up the chlorine that kills germs.”
ACE-K isn’t the only way to estimate the amount of urine in pools and hot tubs.
Ernest R. Blatchley III, an environmental engineer at Purdue University who studies swimming-pool chemistry, has done it by measuring urea, a component of urine. German researchers have used calcium, which is also excreted in urine.
But there is another tool that anyone can use: Their nose.
Appropriately chlorinated swimming pools and hot tubs smell strongly of the disinfectant only when it has combined with substances like urine, lotions and hair products. A healthy pool has very little odor, Dr. Hlavsa said, and it should not turn your eyes red.
The solution to keeping it that way is straight forward.
Shower for about one minute before swimming to remove personal care products and traces of feces. And stop using the pool like an Olympic-size toilet.
