KEY Health Facts You Need to Know if You Have or Use a Pool

pool, chlorine, chlorinated water, disinfection byproducts, disinfectant byproducts, DBP, DBPs, THMUnlike tap water distribution systems, pool water is recirculated every six to eight hours. During this time, swimmers’ activities can introduce a broad range of organic pollutants that can react with disinfectants.

When chlorine reacts with these precursors, a variety of chemical reactions take place, including the formation of disinfection byproducts (DBPs).  Chlorinated DBPs can promote respiratory ailments.  Standard pool filtration systems are ineffective at removing the precursors.

Researchers have recently made progress in developing a sensitive new technique to measure DBPs.  It is called membrane introduction mass spectroscopy, or MIMS.  Using this technique, scientists evaluated compounds released during reactions of chlorine with four organic compounds known to be introduced by swimmers. The results showed that the common compounds contributed to the formation of trichloramine and other DBPs.

The researchers then went on to look at the distribution of disinfection byproducts in 11 types of indoor pools, and found that more than three-quarters of the pools had inorganic combined chlorine concentrations that exceeded National Swimming Pool Foundation guidelines.

Dr. Mercola's Comments:

There’s no doubt swimming is a phenomenal form of exercise, but where you swim can make a big difference in your health. Swimming in chlorinated swimming pools, especially indoor pools, can lead to a number of health problems.

Swimming Pool Chemistry and Your Health

To protect bathers from bacteria and other potentially hazardous organisms, swimming pools are sanitized with large amounts of chlorine. Unfortunately, in recent years scientists have realized that the chemical byproducts formed when organic materials mix with chlorinated water are FAR more toxic than anyone could have guessed.

Disinfection byproducts (DBPs) are over 1,000 times more toxic than chlorine itself, for example.

In swimming pools, the organic materials that cross-react with chlorine to form DBPs include hair, skin, dried sweat, dirt, and urine. Lotions can also cause harmful chemical reactions.

The Hazards of Disinfection Byproducts

The most common disinfectant byproducts formed when chlorine is used are:

  • trihalomethanes (THMs)

  • haloacetic acids (HAAs) 

Trihalomethanes (THMs) include four different chemicals: chloroform, bromoform, bromodichloromethane, and dibromochloromethane.

THMs are Cancer Group B carcinogens, meaning they’ve been shown to cause cancer in laboratory animals. They’ve also been linked to reproductive problems in both animals and humans, such as spontaneous abortion, stillbirths, and congenital malformations, even at lower levels.

These types of chlorine disinfection byproducts (DBPs) can also:

  • Weaken your immune system

  • Disrupt your central nervous system

  • Damage your cardiovascular system

  • Disrupt your renal system

  • Cause respiratory problems

I’ve already written about the dangers of disinfection byproducts (DBPs) on several occasions over the past few years, mostly as it relates to your municipal drinking water, which is also chlorinated to destroy disease-causing bacteria.

However, many of these risks are actually significantly magnified when you’re swimming in chlorinated water.

Your body absorbs more chlorine and higher levels of DBPs by swimming in a chlorinated pool once, than you would by drinking tap water for one week! So, if you’re a frequent swimmer, this could be a potentially serious problem.

Swimming in Chlorinated Water is FAR More Dangerous than Drinking it

At least two studies support this statement.

According to one study published in the Journal of Environmental Sciences last year, swimming in a chlorinated pool presents “an unacceptable cancer risk.” They concluded that the cancer risk of trihalomethanes from various routes in descending order was:  

  1. skin exposure while swimming

  2. gastro-intestinal exposure from tap water intake

  3. skin exposure to tap water

  4. gastro-intestinal exposure while swimming 

The cancer risk from skin exposure while swimming comprised 94.18 percent of the total cancer risk resulting from being exposed to THMs!

Another 2007 study found that participants who drank chlorinated water had a 35 percent greater risk of bladder cancer than those who didn’t, while those who swam in chlorinated pools increased their cancer risk by 57 percent.

In addition, since these chemicals hover in the toxic fumes just above the pool water, you also breathe them in while you swim. This can have a more or less direct impact on your respiratory health. (Indoor pools are even worse in this regard, as fumes are trapped.)

Swimming instructors, for example, are more than twice as likely to suffer frequently from sinusitis or a sore throat, and are more than three times as likely to have chronic colds than other pool workers with less THM exposure, such as catering employees or receptionists.

And according to a study published just two months ago, the impact of chlorinated pools on the respiratory health of children and adolescents appears to be far more important -- at least by a factor of five -- than that associated with secondhand smoke!

They concluded that in children with allergic sensitivities, swimming in chlorinated pools significantly increased the likelihood of asthma and respiratory allergies. For example,

  • The risk of hay fever was up to seven times higher for “sensitive” children who swam in chlorinated pools for more than 100 hours

  • The risk of allergic rhinitis was up to 3.5 times higher for those who swam in chlorinated pools for more than 1,000 hours

The longer the children spent in the chlorinated water, the greater their risk of asthma and allergies became.

Experts estimate that many allergies and immune-system diseases have doubled, tripled or even quadrupled in the last few decades, so chlorinated water is an important, potentially toxic, exposure to watch out for, particularly if you or your children are already at risk.

Healthier Alternatives to Chlorinated Swimming Pools

If you love to swim but want to maintain high-level health, I strongly recommend avoiding chlorinated or brominated swimming pools.

Ocean water is your best option, if you have access to it. Salt water offers other health benefits in addition to the physical exercise aspect, including:

  • Killing many of the parasites that live on your skin, in your nasal passages, and around your eyes

  • Reducing stress on your immune system

  • Detoxifying and balancing your body chemistry

  • Supplying your body with valuable minerals (as they’re absorbed through your skin)

Your second best bet would be any other natural body of water, such as freshwater lakes.

If your only option is a swimming pool, find a way to keep your pool clean from bacteria, algae, and other organisms without the use of dangerous chemicals. For instance, I’ve found a simple solution that not only keeps your pool looking clean but also helps you eliminate chlorine and the risky byproducts.

The Mercola Swimming Pool Treatment disk uses a unique form of the patented KDFÒ (Kinetic Degradation Fluxion) copper-zinc (CuZn) media that filters your pool water as the water twists and turns through the maze of copper-zinc fibers within. You can read more about it here.

These disks do NOT affect algae, however, so you will still have to “shock” your pool every few weeks or so. Fortunately, there are a number of safe shock treatments on the market that are non-toxic, such as those containing sodium carbonate.

In addition, you can reduce the amount of organic material you bring into the pool by showering prior to entering and teaching your children not to urinate in the water.