Are swimming pools a health hazard?

Swimming is an excellent form of exercise. But like many activities, swimming in a pool has its downside.

Despite attempts to disinfect the pool, some pathogens may still lurk in the water. And research suggests that disinfectants may pose their own health hazards.

Swimming in chlorinated pools, particularly indoor pools, might put kids at higher risk for developing respiratory illnesses, including asthma and hay fever.

In addition, there is evidence that disinfectant by-products–formed when chlorinated water is mixed with microorganisms, human body fluids, cosmetics, and sunscreen–can damage your DNA and increase your risk of cancer.

This sounds rather alarming. Does it mean we should keep kids out of the pool?

Not necessarily. It depends on the pool.

And we should keep in mind: Most studies concern kids who swim regularly. A few visits to the wrong swimming pool are unlikely to cause health problems.

So there is reason is reason for concern, not panic, and parents shouldn’t feel helpless about the potential risks.

Here is an overview of the latest research on swimming pools, pathogens, and disinfectants. At the end of the article I offer tips on how to minimize risks to your child.

Why swimming pools need to be disinfected

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A pool full of humans is liable to contain all sorts of pathogens, and humans are only part of the problem.

Water may be tainted by other sources – organic material derived from decaying leaves, bird droppings, fungi-infested rainwater, or dead organisms.

So disinfecting water is a good idea, and there are several ways to go about it, including ultraviolet radiation and the treatment of water with a copper-silver solution.

But chlorination is the most popular method. It’s cheap and relatively effective (Loret et al 2005). When used properly, it protects swimmers from a wide range of dangerous pathogens, including

• E. coli, Rotavirus, Salmonella, and Shigella (each of which may cause gastrointestinal symptoms and, in some individuals, serious illness)

• Adenoviruses (which are linked with gastroenteritis, respiratory infections, eye infections, and other diseases)

• Pseudomonas aeruginosa (which can cause a variety of diseases, including pneumonia and urinary tract infections)

Before the introduction of effective vaccines, chlorination was also one of the only ways to protect swimmers from diseases like polio and hepatitis A.

But no disinfection method is 100% effective. Some pathogens, like the protozoan parasites Giardia and Cryptosporidium, can survive the chlorination process.

Others are destroyed but only after sitting in chlorinated water for 20 minutes or more. If you are unlucky enough to be in the pool immediately after an infected child defecates in the water, your chances of contracting the disease is very high (Kababjian 1995).

And unfortunately, disposable swim diapers offer very little protection. When researchers put them to the test, they found these diapers released most parasite-sized micro-particles within 5 minutes of hitting the water (Amburgey and Anderson 2011