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.

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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 Lori on
    October 26, 2015 - 5:50am

    Regarding salt pools-if the water is treated inside the "chamber" as you say and no chlorine released into pool, then where does the chlorine in pool water come from? I clean pools. Every salt pool maintains a chlorine level without the addition of chlorine. Unless there is another type salt system that I am unaware of, this is how they all work.

    Submitted by BaselineFoundation on
    October 26, 2015 - 5:13pm

    Yes. The electrolysis of salt in water produces chlorine gas, which is what clears the water. Higher levels of activity are found in the chamber, but some of the gas combines with the water and makes its way into the pool. So, yes, salt pools are chlorine pools, and proper free available chlorine residual should be maintained at all times for adequate sanitation. The advantage of salt pools is that since the most aggressive action takes place in the chamber, chlorine levels can be lower in the pool itself.

    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 Dave on
    May 14, 2016 - 10:21pm

    I just came from another forum, researching on chlorine pools. And I saw documentation on how chlorine can kill our good bacteria in our guts (by swallowing while we swim), hence producing Candida overgrowth. It makes sense since chlorine is used to kill germs and other things in pools, it will also kill the good flora in our gut allowing bad bacteria to grow. Also, inhaling chlorine has been linked to deceases like asthma, cancer in women from drinking chlorine water at home, thyroid etc..

    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 Alison on
    January 16, 2017 - 7:22pm
    Provo , Utah

    I've heard that ozone is a much healthier alternative to chlorine for disinfecting pools. Would like comments please.

    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.

    Submitted by Guest on
    September 26, 2012 - 7:42pm

    This article is total bunk. Have you heard of a spike in cancers among regular swimmers? No, you haven't. Chlorine isn't the best option, but it is hardly a risk factor. Further, in a salt system, the pool is still chlorinated, the salt and electricity reaction creates chlorine so you don't have to add it, but the pool water will still test to the same PPM of chlorine as a non-salt system. If you really want to avoid chlorine, try Pristine Blue (copper based), or Baquacil (peroxide). Both are adequate sanitizers, and both are non-chlorine. Any pool professional will tell you however, that if you use a non-chlorine system you will still need to use chlorine based shock from time to time because it is simply the best way to sanitize pool water. This 'health' mumbo jombo is NOT based on actual science.

    Submitted by Gary Crayton on
    November 9, 2012 - 2:40pm

    Perhaps the drinking fountain at the pool should have been tested since both swimmer and non swimmers exhibited these HAA's? The study has too many flaws and variables to have any value. Were all the particiapnts hydrated with non chlorinated water before and after swimming? What were their HAA levels before swimming or even coming to the complex? What were the chlorine levels in the water? This is basically non scientific mumbo jumbo, if you are going to do a real study without an agenda do one, and put the results out for peer review - but don't put out this tripe as science.
    Gary Crayton III

    Submitted by BaselineFoundation on
    February 11, 2013 - 2:28pm

    A number of people seem to have a problem with this report. First they question the fact that you absorb any significant amount of chlorine though your skin. And they also question whether it actually has any health consequences if you do – asking, “Where’s the spike in cancer?” We asked Jon Barron what he thought.  He said:

    Actually, it’s not just one study. There are a number of studies that come to the same conclusion. In fact, they pretty conclusively state that we do indeed readily absorb chlorine and chlorine byproducts such as trihalomethane found in swimming pools – with levels in the body increasing anywhere from 300 percent to an astounding 2,000 percent after just an hour in a swimming pool. In chlorinated water, according to the studies, about 80% of the absorption is transdermal and 20% is through the lungs from when you breathe in the vapors off the water. (As a side note, those figures are essentially reversed in your morning shower when the heat of the water and the fact that it’s being blown into a mist make lung absorption the primary culprit.) Here’s just a handful of the studies that talk about transdermal chlorine absorption.

    As to skepticism about seeing no increase in cancers as a result of swimming in chlorinated pools, that’s harder to address since there are so many factors that come into play that might account for the mind-boggling increase in cancers we’ve seen over the last 100 years. Also, keep in mind that the first use of chlorine as a swimming pool disinfectant was probably back in 1910 at Brown University (W. Bunker, "The Hygenie of the Swimming Pool," American Journal of Public Hygiene, 1910 (20:4), 810-812.) In other words, any increase would have been spread out over 100 years as the use of chlorine in swimming pools increased during that time. It also would be somewhat obscured by the fact the three most common forms of cancer associated with chlorine—urinary, bladder, and rectal—are also associated with cigarette smoking. Incidentally, taken together, these three cancers account for some 181,000 new cases every year in the US alone ( I’m not sure I would call that incidental.

    The bottom line is that until studies come along that refute the “many” studies that now find problems with swimming in chlorinated water, why not reduce your exposure as much as possible if you can. As Beth’s blog mentioned, you don’t have to give up swimming in pools. You just want to take steps to reduce the chlorine levels found in the pools you swim in. 

    Arguing against reducing your chlorine exposure seem to pretty much defy commonsense—particularly since said steps don’t require you to stop swimming. But then again, that’s just me.

    Submitted by Jesse Dutra on
    May 7, 2013 - 5:01pm

    Take a look at the Natural Swimming Pool; or Natural Swimming Pond (NSP) originated in Austria & Germany over 25 years ago. Today, there are more than 20,000 Natural Swimming Pools across Europe; including large, public swim facilities. The Natural Swimming Pool is based on limnology; a scientific system that allows plant and microorganisms to naturally filter the swimming water; which make it free of chlorine and other harmful chemicals.

    Submitted by helene a. gomulka on
    May 21, 2013 - 10:08am

    love 2 swim-was not until I started using a public pool that it began to effect my teeth.the metal in my dental work-added 2 the problem-as metals r in chlorine according r my new dentist-after removal of the metal in my mouth-went swimming again at the community pool-with a month by breathing in the chlorine-even the new dental work absorbed the actualyy conducts electricity in your face----alarming-if u have any chemical or metal sensitivities at all-stay away from all metal dental work and stay away from chlorine-saw the dentist this morning-reconfirmed what I just commented about---so if u have a bridge-if u have a partial-if u have an implant-beware not only of the metal-chemicals in that-but in the chlorine-in so far as the epa controlling the levels of chlorine in our drinking water-southwest florida is so polluted as republicans refuse to even attend epa meetings in Washington and it flows directly into rick scotts state-charlotte-Sarasota county both went into a public health alert at their beaches-February 2013-some beaches were posted-some were not-utility spills-of sewer-fdep-did nothing-still saying red tide in a natural occurrence in both counties-reference-marin county California-sewer plant spill-fined tremendously-fueled red tide-reference-laguna beach California-timing mechanism off-spilled billions of gallons sewage-fueled red tide again-heavily fined. florida has a lot of pools-a lot of beaches-but because republicans do not believe facts-science-they r in effect harmful 2 your health-and even when u bring those facts 2 their attention-whether it b chlorine in pools-harmful bacteria in the gulf-lose doses of chlorine having 2 b used in the drinking water to combact all the pollution do their greedy over-development -they do not care-lucky I found a dentist who was educated enough-as 3 of them after spending thosands-did not even know these things---as they say welcome 2 flori-DAH...DAH. retire someplace else.....

    Submitted by garry on
    September 23, 2013 - 12:23am

    In the swimming pool people use many type of chemicals for the color change or for the water purity so these type of things don't create anything for the users. 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 so these type of things don't create any problem for the people.

    Submitted by Lisa on
    December 24, 2013 - 5:18am

    What do I do about my pre-schooler's bath water? I can smell the chlorine. It is not like a pool or living in a big city but it is there. We put a filter over our shower so that helps there but this does not help with his bath water. The spout that is in the tub is a standard one with no screw threads so nothing could be affixed to it. I hate that he has had baths every day for four years in the chlorinated water. I have seen "balls on a chain" you can swish in water to be rid of chlorine but wonder how efficient they really are. Does anyone have any recommendations?

    Submitted by BaselineFoundation on
    January 2, 2014 - 10:41am

    Not sure about balls that you drag through the water. But there are balls that hang from the spout so the water passes through the ball on its way to the tub. Those work. Search under chlorine bath filter.

    Submitted by Lisa on
    January 3, 2014 - 5:54am

    I have seen those but I don't think they will work for us. Unfortunately the only adjuster for our bath is a handle that makes the water colder or hotter. There is no adjuster for water flow so the water comes out fast and hard in the tub no matter what. You cannot just let it trickle out.

    Submitted by Adriana on
    June 30, 2014 - 2:21pm

    We put as you a filter in our shower, but we ALSO added a long hose to the connection. So we fill our toddlers bath with the hose that brings water from the filter. If you do not have a hose, simply plug the tub and turn on the shower to fill the tub. Do not use the bottom faucet. That way, your toddlers water is filtered water with no/minimal chlorine or HHA's

    Submitted by Davido on
    May 20, 2016 - 4:41pm
    Dallas , Texas

    I mange 2 pools and a Spa and sorry, I will not go into any of them. Bromine and Trichlor even a 3-5ppm is to much for me.


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