Toxins in Chlorinated Pools | Natural Health Blog

Date: 08/18/2011    Written by: Beth Levine

The Danger of Swimming in Chlorinated Pools

If you wait long enough, "science" often catches up with the alternative health community. In this case, it only took several decades for researchers to confirm what alternative healers like Jon Barron have been saying almost forever -- that if you've been splashing around in a chlorinated pool, you may be subjecting your body to some serious toxins.

A recent study at the University of Cordoba in Spain found that a group of by-products of chlorine called haloacetic acids (HAAs) was present in the urine of swimmers less than 30 minutes after they emerged from the pool.1  This dangerous chemical is only allowed in restricted amounts in our drinking water by the Environmental Protection Agency because it has been associated with cancer and birth defects in other research.

There were 49 participants -- both children and adults -- in the study.  All of them either swam in or were pool workers employed at indoor and outdoor chlorinated pools.  When their urine was tested, the HAAs showed up 20 to 30 minutes after the chlorine exposure took place.  They continued to appear in the urine for up to three hours before they were fully excreted.

The scientists suggested that the vast majority of the contact with HAAs was most likely caused by the volunteers swallowing small amounts of the pool water as they swam.  However, inhalation and absorption through the skin clearly also created exposure, since not every subject actually entered a pool.

Unsurprisingly, those who swam stored up HAAs nearly four times as quickly as those who simply worked by the pools.  And children had higher levels of HAAs after taking a dip than the adults did, which makes sense since the younger the skin, the faster the absorption rates.  Therefore, the younger the child, the more dangerous the exposure to chlorinated pool water can be.

Chlorine is added to both the water we drink and the water of many pools because of its ability to kill bacteria for our safekeeping.  Ironic, then, that it breaks down in the water and creates these harmful HAAs.  Although the amount of chlorine put into a pool is supposed to be regulated, there is no way to oversee every pool in backyards, health clubs, hotels, community parks, and so on to know that the levels are anywhere near safe -- if any such level actually exists.

The same concerns relative to bathing in chlorinated water also apply to swimming in pools with chlorinated water. It's very bad, and you absorb a great deal of chlorine very quickly through the skin. Also, as I already mentioned, the younger the skin, the quicker the absorption -- which means your toddler is at particular risk.  Incidentally, Jon Barron describes in Lessons from the Miracle Doctors an experiment you can perform at your convenience to see just how quickly you actually absorb chlorine through your skin.

Stop by your local swimming pool supply store and pick up a chlorine test kit. Fill a glass with some of your local tap water, or water from a chlorinated swimming pool, and test it with the kit. The water will change color according to how much chlorine there is in the water. Now, fill up another glass with water from the tap. This time, soak your hand in the water while wiggling your fingers about for 60 seconds before testing. Notice how the water now shows virtually no chlorine. In just 60 seconds, you absorbed all of the chlorine in the water into your body through your hand. The absorption factor is that dramatic.  And it's not just toddlers with young skin that need to worry. Women should take special note that breast tissue is the most absorbent tissue in the body. Soak your breast in the same water, and it will clean out all of the chlorine in just 20 seconds.

So if you've got your own pool, you might want to consider keeping it clean without chlorine, or at least with minimal chlorine.  One of the most popular options now to avoid using chlorine is saline -- or salt water -- pools.  With this method, the pool is kept clean by adding a small amount of salt to the water every few months.  The water is pumped through a cell chamber that breaks down the salt into its components, which produce chlorine gas that cleans the water in the chamber.  The water is bacteria-free when it is once again released into the pool and the chlorine gas that had been formed is never released into the pool.

The initial cost of using salt to keep your pool clean is more expensive than a chlorine start-up, but since you don't have to add it frequently, the costs become lower over time.  There is also much less overall maintenance with a saline pool.

Ionization is another method of keeping your pool clean.  Copper and silver coils that have been ionized, or become positively charged, are used in the pool to purify the water as it circulates.  The positive ions can kill much of the algae and bacteria that end up in the water, but pool experts still recommend using a very low dose of chlorine to be certain it's fully sanitized.

Filters are an important consideration as well.  The right filter can help you use a much smaller amount of chemicals to keep the water pure.  Activated charcoal filters are probably the most effective, but are also the most expensive.  Filter cartridges require more maintenance but they cost less and should last for several years.

There are also chlorine-free chemicals available, but many of these are not any safer than chlorine itself.  Do your homework if you want to explore this option to ensure you don't trade one toxic chemical for another.


1 Cardador, M.J. and Gallego, M. "Haloacetic Acids in Swimming Pools: Swimmer and Worker Exposure." Environmental Science & Technology. 7 June 2011.  American Chemical Society. 8 August 2011. <>.

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    Submitted by manuel ulloa on
    August 29, 2011 - 5:01pm

    A.- Regarding sea-water what comments do we have on this topic ( good / bad , Inocuous ?

    B.- what about using hidrogen - peroxid technical-grade ( or so )to clear up swimming pool`s water? Is this a worth solution in health and economic terms?

    Submitted by prema on
    August 29, 2011 - 7:41am

    i was wanting to swim this summer ..... i am older and i was thinking that swimming would be the best exercise....but i hesitated due to the chlorine so i am thankful for this article...
    many years ago i researched this out too.....i had read that if you put coconut oil all over your skin that the chlorine would not be absorbed....i mean people go in the pools with all that sunscreen on and that is oily so why not coconut oil...
    do you know anything about this/....thank-you

    Submitted by BaselineFoundation on
    August 29, 2011 - 1:04pm

    Hadn’t heard that. But keep in mind, even if you are able to plug all your pores – and how healthy is that – you’re still going to take in chlorine fumes when you breathe.

    Submitted by Marc Masnor on
    February 10, 2013 - 1:16pm

    Please go swim. The Chlorine in a pool, if well maintained, will not harm you. Chlorine is NOT quickly absorbed by the skin. Keep browsing. Your health will be better for the exercise in the pool. The "test" of putting your hand in the water is bogus.

    Submitted by Martin on
    November 14, 2013 - 3:14am

    I believe that chlorine in a pool is definitely the less worse of the alternative - As of today we don't have any comparable oxidizing alternatives capable of killing most (not all) pathogenic organisms in the water. If you are actually aware of the contamination in a pool and what this can do to the human body especially without any desinfectant agent such as chlorine - You would NEVER dip even your foot in a swimming pool again - There are no such places on Earth as pools where human body fluids and solids as well (feces in various states) urea skin cells etc. from both healthy but also potentially sick people are exchanged - keep that in mind always...

    The downside and potential carcinogenic effect of the chlorine (Trihalomethanes -THM) occurs mostly when the chlorine is acting as your primary water filtration system. The job is to keep the chlorine active in only its desinfective stage as much possible and therefore not allowing it to function as a "chemical water treatment filter".

    Therefore it is crucial to have an effective and rapid removal of organics from the pool by investing in a well-proven water treatment filter technology and also to assure that your pool is well monitored and operated at all times.

    The real big problem in a pool is actually the load of guests bathing and their hygiene or lack of hygiene!!! Always thoroughly shower RIGHT BEFORE entering a swimming pool this will actually reduce the contamination of the pool X 20 !!! Significantly reducing the chlorines penchant from interacting with and its ability to decompose organic matter.

    There are deviations of factors between indoor and outdoor pools (UV radiation etc.)

    NB: Skin treatment products such as oils sunscreen and other "pollutants" may be necessary for skin health causes be they definitely do nothing good for the pool water - so you should always carefully consider the necessity of applying such products.

    Submitted by Guest on
    August 29, 2011 - 8:47am

    What about using iodine instead of chlorine or salt? That would make everyone healthier and keep bacteria at bay? That is what used to be used before chlorine and everyone was healthier then! Technology doesn't always do us any favors. It isn't always better "now".

    Submitted by tgrizzelle on
    August 29, 2011 - 10:31am

    have recently been viewing material re: pool "shock" and wonder if this is source of the dangerous chlorine described here. also, wonder if the chlorine dioxide which occurs after mixing sodium chlorite with ascetic acid is also implicated as dangerous from this study?

    Submitted by BaselineFoundation on
    August 29, 2011 - 2:25pm

    "Shocking” a pool involves adding a powerful oxidizing agent (usually chlorine) to break down organic compounds and ensure that the pool is properly disinfected and safe for swimming. In fact, pool shock treatment is also referred to as super-chlorination or super-oxidization. Obviously, the higher the level of chlorine in the water, the more dangerous it is, but problems with chlorine and swimming pools exist wherever chlorine is used to purify water. Heck, it presents a problem in your shower and bath – and that water isn’t shocked. As for chlorine dioxide, it wasn’t particularly singled out in the study – but yes, it is dangerous to handle and breathe.

    Submitted by Guest on
    June 4, 2012 - 8:25pm

    I was wondering could swimming in chlorinated pools which I have done 3times a week for the last couple of years be responsible for my reoccuring UTI. I seem to be constantly on antibiotics even now after I have not been in the pool for about 6months now. maybe there is a connection? any suggestions Thanks

    Submitted by Guest on
    September 25, 2012 - 5:35am

    Chlorine kills bacteria - good and bad in and on your body. The body needs bacteria to efficiently run. Same with the antibiotics that you are taking every few weeks. Look into Natural Swimming Pools - plants, not chlorine purify the water.

    Submitted by Joe on
    August 25, 2012 - 8:25am

    in a commerical pool, if the readings are above a 10.0 what are the dangers to the skin and body?

    Submitted by Meade on
    August 22, 2012 - 4:57pm

    Nonsense. Health wise, swimming pools are the safest water to swim in. Far safer than our oceans, lakes, and rivers, which carry tons of pollutants and toxins. Chlorine while it may be technically a "toxin" is no more harmful to us than many household cleaners we use daily. There are lots of swimmers who are cancer free. I would much rather be in a chlorinated clean swimming pool that is maintained properly than a dirty lake, river, or ocean. No sharks , either! Another bonus.

    Submitted by Guest on
    September 9, 2012 - 7:56am

    if this is true, then why don't we see an increased incidence of cancer in pro/ olympic swimmers? they spend MUCH more time in a pool than the average pool go-er.
    just curious, because if i quote this study and one of my pool loving friends questions me, then i'll have an answer.

    Submitted by BaselineFoundation on
    February 11, 2013 - 2:23pm

    I don’t know about studies for Olympic swimmers in particular, but swimming in chlorinated pools has been associated with:

    An increased risk of bladder cancer: Http://

    An increased risk of asthma: Http://

    Increased dental erosion: Http://

    That should get you started in any discussion with your pool loving friends.

    Submitted by Alex on
    October 1, 2012 - 12:48pm

    Chlorine now a days s not the best way to keep your swimming pool clean, there are some innovative products that have the technology to keep bacteria, and other pathogens out of the pools. For example BIOPISCINAS ( biopool) is a product from Argentina that beats all of the non chlorine products in the US, The tecnology that uses is superior to the copper and peroxide, Biopiscinas uses Guanidina more stable that the one using Biguanide. Guanidina its performs better that other non chlorine products in the market.


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