The odds are great that any public swimming pool you visit will have a good amount of human waste floating around in it, making it akin to a huge toilet bowl. That doesn't even account for other bodily fluids emitted from the nose or mouth, sweat or human skin follicles that may find their way into the pool.
Americans love to go swimming, so we’re talking about a large number of people who are exposed. The Centers for Disease Control and Prevention estimate that there are approximately 10.4 million residential and 309,000 public swimming pools in the United States. Each year, people older than six account for roughly 301 million swimming visits, as calculated in 2009. The CDC say that 36 percent of children ages 7-17 years old and 15 percent of adults swim at least six times during the year.
The CDC also claim that close to 57 percent of spas violate local environmental health codes, with about one in nine (11 percent) so severely violating health standards that it should be closed immediately.
The term for illnesses caused by swimming is recreational water illnesses (RWI), which are the product of germs ingested by breathing in mists or aerosols, swallowing tainted water, or contacting contaminants found in hot tubs, water parks, swimming pools, play areas, interactive fountains, and even lakes, oceans and rivers. Illnesses can be caused by contact with fecal matter or can be the product of contact with chemicals found in the water or evaporated chemicals that are now breathable in indoor air.
Water-Related Recreational Water Illnesses
There are many water-related recreational water illnesses. Gastrointestinal disturbances, ear, eye, skin, respiratory infections, neurologic disorders, and infections of open wounds are among the problems that swimming in tainted waters can cause. The most common illness spawned by water is diarrhea, which is caused by ingesting cryptosporidium, shigella, giardia, norovirus or E.coli germs. Swallowing, inhaling mists or aerosols, or general contact with contaminated water can cause RWIs. They can also be caused by chemicals in the water or chemicals that evaporate from the water and cause indoor air quality problems.
Over the past two decades, recreational water illnesses are on the rise, with most outbreaks attributed to swimming incidents. Even the best-maintained and most health-conscious pools can be the site of a cryptosporidium outbreak because the virus can stay alive for days in the hot, moist conditions. From 2004 to 2008, reported crypto cases rose from 3,400 to more than 10,000, a 200 percent increase from the 2004 to 2008 period.
Pools also can cause other problems. Here are four that can be caused by swimming in public:
1) Researchers have found that chlorine increases your risk of developing asthma, with the chemical reaction of chlorine mixed with sweat, urine, skin and hair contributing to the problem.
2) Legionnaire’s disease is a bacterial lung infection that resembles pneumonia and can be caused by indoor pool water vapor. Its symptoms include a high fever, cough, shortness of breath and muscle aches.
3) Athlete’s foot is a skin disease that can also be acquired in a pool environment. The National Health Service reports that swimming pools, communal showers and changing rooms are among the prime locations where the highly contagious athlete’s foot is spread.
4) Finally, cancer is a danger when swimming in chlorine treated waters. A study by the Environmental Health Perspectives noted that 40 minutes of swimming in chlorinated water can be linked to an increase in blood lymphocytes, which is a cause of increase cancer risk.
Myth vs. Fact
Despite what you may have heard, there is no magic chemical that will turn the water a different color if someone urinates in the pool.
However, as one swimming pool expert noted, if such a chemical did exist, most public pools would have water that’s bright purple. Quartz magazine reported a 2012 survey that found almost 20 percent of adults – not children, adults – admitted to having urinated at least once in a public pool. And even if you’re not proactively urinating in the pool, the so-called “drip factor” can contribute as much as two shot glasses full of urine during a typical session.
But peeing in the pool is not just a harmless prank. Research by Purdue University in Indiana and China Agricultural University indicates that when chlorinated water and urine is mixed, two potentially dangerous chemical byproducts form. Urine mixed with chlorine produces cyanogen chloride and trichloramine. If inhaled, both can affect the function of lungs, heart, central nervous system and other organs. Worse, the dilution factor of gallons of water and filtering aren’t much protection – when the researchers added more uric acid to water that already contained the chemicals, the cyanogen chloride level went up. Depending on the temperature of the water, its existing pH levels and the amount of chlorine, uric acid can contribute as much as 68 percent to cyanogen chloride levels, the researchers discovered.
Swimmers and lifeguards are all at risk of developing health problems from repeated exposure to the chemicals. Fortunately, it takes a lot of urine mixed with chlorine to produce enough of the cyanogen to cause problems. The research found that their mixing in high concentrations of urine and chlorine in the lab resulted in concentrations of about 30 micrograms per billion. That’s less than the World Health Organization’s guideline of 70 parts per billion as a threshold for unsafe levels of cyanogen chloride in drinking water. One scientist estimated that creating conditions that would cause death would need up to 2,500 parts per billion, which would essentially be two parts water to one part chlorine, a combination that would instantly result in death for anyone foolish enough to jump in.
But Wait, There’s More
That’s just the result of the urine analysis of pool water. But there’s also fecal matter floating around in public pools, and that has a whole other laundry list of problems that can be created.
Despite the gloom and doom, it’s worth remembering that millions of people enjoy swimming each year without developing so much as a sunburn. If you attend a well-maintained pool, wear protective flip-flops and avoid swallowing excessive amounts of water, your risk of health problems related to your swimming activities will be minimal. Go out and enjoy – the exercise is good for you.