Is Your Swimming Pool Poisonous?

Ever wonder why public pools require you to shower before jumping in?  That just sounds like a waste of time—why is it so important to rinse yourself off with water before cannon-balling into a swimming pool full of… more water?

Easy.   Skipping the shower means a toxic swim.

And toxic pool water means possible birth defects, DNA damage and even cancer.

Don't fly one of these over your pool!

Don’t fly one of these over your pool!

Okay, in all reality, most pools are nowhere near toxic, but it doesn’t take much to turn a healthy pool into a bath of poison.  The disinfecting chemicals used in pools and spas can react with organic material—like your body oils, hair and sweat—to create a toxic swimming environment for everyone.

Don’t freak out just yet.  There are plenty of ways to avoid a pool of poison.  Step 1: shower before entering a swimming pool.  Step 2: Comply with pool and spa disinfection standards, making sure you have safe amounts of chemicals in your pool.  Step 3: Encourage others to do the same.

Some of the most important aspects of keeping your pool both clean and healthy include knowing exactly what chemicals you’re using, whether or not you’re adding the proper amounts and whether any of these chemicals react with others.  It’s also equally important to test your water quality and chemical levels regularly.

Usually, pools are disinfected with chlorinating agents, such as chlorine (buy it here) and chloramines.  These chemicals come in two types:


         Calcium hypochlorite

         Lithium hypochlorite

         Sodium hypochlorite


         Trichloroisocyanuric acid

         Potassium dichloroiscyanurate

         Sodium dichlorocyanurate

Both inorganic and organic chlorinating agents effectively disinfect pool water, but they should never be used at the same time.  They are not compatible and can cause disaster when mixed.  Even using the same scoop for both chemicals is enough to cause an explosive mixture.  They are alike, however, in that they both generate disinfection by-products (DBPs).

Disinfection by-products are compounds created when disinfectants, like chlorine, react with organic matter in the water.  The danger of these compounds varies, but according to University of Illinois geneticist, Michael Plewa, some are toxic, some genotoxic (damaging to DNA), some cause birth defects and some are carcinogenic.  He and his team of researchers discovered that DBPs in drinking water containing iodine tend to be highly toxic and genotoxic, while those containing nitrogen are more toxic, more genotoxic and usually carcinogenic compared to those without nitrogen.

And what about swimming pools?  Plewa found that swimming pools and spas are DBP reactors.  Sweat, sunscreen, cosmetics, hair, oils, urine and other organic materials come off of the body in chlorinated water and are recycled over and over again, creating considerably high levels of DBPs.  Those who are exposed to extremely high levels of DBPs on a regular basis—such as professional swimmers—have been shown to possess higher rates of bladder cancer and asthma.  Because these compounds are absorbed through the skin, as well as inhaled at the surface of the water, swimmers with greater and longer exposure to such chemicals are more likely to encounter problems than occasional swimmers.

You might be thinking that chlorine is a terrible way to disinfect a pool.  That’s not the case.  Swimming pools, particularly public pools, are chlorinated to keep bacteria and pathogens at bay, and that’s exactly what they do.  Chlorine is an efficient and effective means of keeping a swimming pool clean—the only stipulation is that it should be used in compliance with pool disinfection and chemical standards and that organic material is controlled.

That is why showering before swimming is so important.

In addition to keeping organic material out of your pool, you can also carefully monitor what types of and how much chemical you’re using.  Make sure that you’re confident releasing chemicals into your pool before you do so.  If you don’t feel up to the challenge, contact your pool provider or seek other professional advice. You should also make sure to add chemicals to your pool individually.  Some chemicals, when mixed together (even in small quantities), can form deadly or dangerous gases.  Make sure you give your pump an hour to distribute one chemical before adding another.

Never add chemicals to your pool while it’s in use, and try adding them during the evening if you know you’ll be swimming the next day.  Water testing is also important when determining what to put into your pool, because the amount of chemical you release depends on the water’s pH, in addition to your pool’s capacity and volume of water.  Following these guidelines can help you and your family avoid stinging eyes, itchy skin, shortness of breath and other symptoms of an overly-treated swimming pool.

You may also like to turn to chemicals that don’t create DBPs.  For example, bromine (buy it here) is a common substitute for chlorine that doesn’t react with organic matter to cause irritation or dangerous effects on the body.

It is also preferred for not releasing the odor that chlorine does when reacting with organic matter.  For swimmers who are plagued by asthma and allergies, low chlorine and chlorine-free products are available to prevent irritation by DBP-contaminated air.

Whether you choose to maintain a clean and healthy pool with chlorine or with other types of disinfectants, avoiding a toxic experience is completely possible—it just takes chemical responsibility, some safety measures and a good ole shower.