Why You Should Think Twice Before Taking a Dip In Your Neighborhood Pool

Canadian researchers found 570 times the amount of ACE-K in tap water in swimming pools. Photo by The New York Times.

Researchers at the University of Alberta in Canada just confirmed our worst fears about pee in swimming pools, pushing avid swimmers to re-think that dip they take in the community pool each summer.

The recent study, published in the journal “Environmental Science & Technology Letters” on Wednesday, March 1, revealed that the average swimming pool contains gallons — yes, GALLONS — of human urine. To determine the degree of pee contamination, researchers collected samples from city pools and hot tubs between May and August of 2014 and tested them for a common artificial sweetener called acesulfame potassium or ACE-K.

The sweetener, normally found in grocery store staples like packaged desserts and diet soda, was ideal in helping scientists detect and measure urine levels, as the ingredient isn’t metabolized by the body and is excreted exclusively through urine. Moreover, it isn’t broken down by chlorine.

“Analysis of more than 250 samples from 31 pools and tubs from two Canadian cities showed ACE in all samples,” researchers wrote. “Concentrations ranged from 30 to 7,110 nanograms per liter — [which is] 570-fold greater than” levels found in tested tap water.

Based off of these measurements, scientists Lindsay K. Jmaiff Blackstock, Wei Wang, Sai Vemula, Benjamin T. Jaeger and Xing-Fang Li concluded that the average 220,000-gallon commercial-size swimming contains nearly 20 gallons of pee. Neighborhood swimming pools contain about two gallons.

Not only is the thought of swimming in human lemonade gross, but it raises concerns about health as well. So, exactly how harmful are concentrated levels of “pool pee” to the human body?

Researchers pointed out that while urine itself is sterile, its many nitrogenous compounds can react to form harmful disinfection byproducts, or DBPs, when in contact with disinfectants like chlorine. Prolonged exposure to volatile DBPs can cause a plethora of ailments including eye irritation, respiratory irritation and even occupational asthma, according to the study.

Bodily fluids like sweat can also bond with chlorine to create irritating chemical byproducts.

Despite these potential health risks, Clifford Weisel, Ph.D., an environmental health expert at Rutgers University, says you shouldn’t cancel plans to hit the pool just yet. Rather, swimmers should be more aware of the risks and understand how to combat them.

First things first: Don’t pee in the pool. The University of Alberta research team indicated that almost 19 percent of adults admitted to “taking a leak” in a swimming pool at least once in their lives. This could potentially be harmful for those with respiratory ailments, especially in indoor swimming pools where compounds build up in the air above the water. There’s also less natural sunlight here, making it less likely that the compounds will break down.

Secondly, lead researcher Xing-Fang Li suggested showering for at least one minute before getting in the pool. This way, you remove the sweat and other bodily gunk that may react with chemicals in the water. It’s also recommended that you rinse off after leaving the pool.

Ernest Blatchley III, an environmental engineer at Purdue University, explained to NPR that “it’s not uncommon for water in a pool to go unchanged for years,” leaving the contaminated water to sit and worsen over time. He said pool managers resort to adding even more chlorine to their pool, which only exacerbates the chemical byproducts. The only true way to disinfect a pool that has been peed in is to replace it with fresh, clean water.


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