View Full Version : Long term Health Effects

February 11th, 2002, 02:45 PM
I am 47years old and have returned to swimming as a fitness choice. I get 3 workouts of 2500yds/week and feel great. I also have an inground pool that my family enjoys in the summer months. My question relates to the long term consequences of chlorine exposure. Do studies exist that show whether swimmers have an increased health risk to cancers? Has anyone looked at pool chlorine exposure as a health risk in any way? The pools I swim in all use chlorine as a sanitizer and I would hate to think my exercise regimen may be doing me more harm than good!

February 11th, 2002, 03:08 PM
I can't answer your specific questions (although will be interested in other responses); however, one tip I do have is to always shower right before you swim. I've read and heard this decreases the amount of chlorine your body and hair absorbs. Supposedly the dry body absorbs a large portion of the moisture at the initial time you get wet. I think someone also posted once that showering before jumping in the pool also decreases the amount of chlorine your bathing suit absorbs and hence can help your suits last longer.

Tom Ellison
February 11th, 2002, 04:04 PM
Gosh I hope not, becasue if they ever discover that chlorine causes serious health problems...I am in big, big trouble.

Bert Petersen
February 11th, 2002, 06:21 PM
This is a serious question and deserves some air time. As a retired coach and pool manager, I feel I have some good ideas. First, let me tell you about the chemical factory I swim in. This is a fairly new 25 yard - 8 lane pool in a High School. It has an Ozone System for sanitizing the water. Unfortunately, no-one seems to know how to run it and so the pool personnel (janitors) just continue to use Chlorine ! Incredible ! After I do my workout in the evening, I must not only shower like a surgeon readying for an operation, I must also completely cover myself with the lotion du jour or else suffer a night of scratching and listening to my wife say " you stink". Even with this, I worked out Thur. night and by the Sat. AM shower at home, Chlorine was still to be smelled coming from my pores. That ain't right, folks !
Now, I have read articles that suggest Chlorine may be hazardous to teeth and I darn sure know that it sets off my allergies bigtime. I take an anti-histamine before and after for this very reason. Don't tell me Chlorine is not an allergen ! By the way, goldfish will not survive in tap water that has 1/100th of the Chlorine in most pools.
In 1986 !!!, I swam in the Worlds at Tokyo, Japan. There was no chlorine in the pool and we could all swim without goggles.
Here's the problem : Many pools in the USA are run or serviced by boneheads who do not have to swim in the soup they create. The standard line is to just add chlorine and then try to cancel it out with Soda Ash. Most of us spend all of our aquatic time swimming in dilute Hydrochloric acid. Anyone else care to weigh in ??? :mad:

February 11th, 2002, 10:37 PM
If you can smell the chlorine in the air then it isn't right mixture in the pool. I must have it good because at my pool you cannot smell the chlorine, I don't itch if I don't put on lotion, my hair is okay, and the ph isn't so bad that the eyes sting. One of the instructors went to pool school and does all the water chemicals. She doesn't want to be in it if it isn't right. :cool:

February 11th, 2002, 11:06 PM

What's the name of the pool? The chief "chemist"?

I would like to at least give the information to my pool people. Fortunately, I like the smell of chlorine ... warm fuzzies about working out or something. But, it is a major smell and a major eye-stinger. At least I don't itch.


Kevin in MD
February 11th, 2002, 11:21 PM
If you think the long term health effects of swimming in chlorinated water is bad ...

Long term effects of swimming in untreated water is even worse!

What's better, swimming while exposed to swimming or not swimming?

Ozone pools are a great idea but I'm not convinced on how much of the ozone remains in the water. This in turn makes me wonder about the kill time of ozone treated pools.

Kevin in MD
February 11th, 2002, 11:23 PM
swimming while exposed to chlorine I mean

February 12th, 2002, 09:55 AM
Thank you for your posts. I'm actually looking for prospective or retrospective epidemiological studies on swimmers at the recreational or competitive level. I recognize that there are large variations in the "soups" we swim in and I certainly hope that swimming in sanitized "soup" is better than no swimming at all. However, long term exposure to oxidants like chlorine is something I feel is worthy of study. I take antioxidants (Vit E) and shower with antioxidant soaps but there is at best anecdotal evidence to support this as helpful (or even necessary). Please keep posting!

February 12th, 2002, 01:17 PM
Showering beforehand might keep chlorine from geting in through the skin so much, but that benefit gets cancelled out fast when you drink a couple gallons from someone's butterfly kick ahead of you. I try not to think about it too much.

February 12th, 2002, 03:57 PM

This might be something of interest, IndyJR. After reading through this, I've decided to skip practice tonight.

Philip Arcuni
February 12th, 2002, 04:35 PM
Sometimes the pool water makes my body hair disappear. I call this the 'dilute Nair effect' and makes shaving for big meets easier. It usually means the water is too alkaline. So what happens to the lungs when you breath that stuff? I know of several older swimmers that have developed excercise-induced asthma. I *don't* know the cause, but I wonder . . .

February 12th, 2002, 06:57 PM
Tens of millions of people have been drinking chlorinated water from their taps for generations. You can smell the chlorine. No one seems to have associated it with any illness

February 14th, 2002, 04:25 PM
Okay some thought from a pool person and swimmer.

The use of Ozone as a disenfectant in pools is only partially true (at least in Oregon) we have an ozone system (about the size used for a small waste water treatment plant yet our pool is a 25meter by 25 yard pool). We are required to keep a trace amount of disenfectant (chlorine in our case, but could be bromine or something else) the reason being is all of the ozone disenfecting is done in the backroom, the ozone is injected into the water lines and then filtered out later before the water returns back to the pool. When we fill our small toddler pool after a scrub down, the incoming tap water is cloudier then what our lap pool is - something to be said about our pool treated water versus our tap water.
How much disenfectant you use in a pool depends on what you are using and the pool pH. For chlorine the pH controls how volutile (for better words) it will be, you will actually have better disenfection with a pool that has .4ppm (parts per million)chlorine and a pH of 7.2 than a pool with 4.0ppm and a pH of 7.6. As for the smell, burning eyes things like that has to do with your combined chlorine or chlorimines - this is what happens after your chlorine does its job disenfecting, a high combined chlorine results in bad water (smell & burning eyes). Going back to Ozone, ozone actually destroys combined chlorine - so how good is this - we play water polo for 1-2 hours and do not have burning eyes or halo's around lights when we are done. Lastly as for pool chemist schools there are several organizations that teach pool chemistry the biggest two certifications tend to AFO (Aquatics Facility Operator) or CPO (Certified Pool OPerator).
This is probably more than you wanted to know about pool stuff, have fun swimming.


February 24th, 2002, 07:53 PM
Everything in life has a benefit/risk ratio.

There is no doubt that swimming in chlorinated water exposes one to choramines, which are potentially mutagenic/carcinogenic and which clearly increase the risk of asthma. It would be important for USA Swimming or someone else to fund a study (a "case control" type of study) to answer the question of whether or not the incidence of sarcomas or leukemia (cancers of childhood and adolescence) is increased in age group and senior swimmers. Owing to the rarity of these tumors in the general population of young people, this should be a "doable" study, requiring reasonable expenditures. At minimum, a central registry should be established, where cases can be recorded and archived, for use by a future researcher. Club swim coaches should be required to report cases of cancer in young swimmers to a central registry (protecting individual privacy, of course).

At the masters level, cancer is so common (and so is death) that it would be a much more difficult proposition to get data to answer the question of whether or not pool swimming has serious long term health risks.

The risks of pool swimming may not be completely known, but the benefits are pretty obvious. I take personal comfort in the fact that my 87 year old father (for the past 5 years a USMS All Star), has been a dedicated pool (and open water) swimmer since age 6 and has so obviously benefitted in so many ways that, to me, it makes the benefit/risk ratio obvious also - decisively in favor of a lifestyle which includes swimming often, swimming seriously, and remaining a competitor for life.

- Larry

>>I am 47years old and have returned to swimming as a fitness choice. I
get 3 workouts of 2500yds/week and feel great. I also have an inground
pool that my family enjoys in the summer months. My question relates to
the long term consequences of chlorine exposure. Do studies exist that
show whether swimmers have an increased health risk to cancers? Has
anyone looked at pool chlorine exposure as a health risk in any way? The
pools I swim in all use chlorine as a sanitizer and I would hate to
think my exercise regimen may be doing me more harm than good!<<

February 25th, 2002, 03:14 PM
Anyone with concerns over exposure to chlorine should visit
the website indicated by Zoomer in his Feb 12 post.

Most local YMCA's are always looking for ways to cut costs--
"defered maintenance" would seem to be a popular choice.
At our Y, the coach
noticed an increase in respiratory problems in the
kids. Found out the air-to-air heat exchanger (a heat saving
device that warms fresh outdoor air while exhausting pool
area air) had never been cleaned! It was "stuffed". It
made a big difference when it was cleaned.

Imagine some of the synergistic effects the could take place
when the chloramines mix with mold spores.

Now that I think about it, I have had bronchitis almost every
January for years (and am otherwise extremely healthy).
Oh, and my back itches like crazy every winter, too.:confused:
What the heck, I'm going swimming anyway.

Philip Arcuni
February 25th, 2002, 03:38 PM
My back itches too, all the time. My wife puts some moisturizer on it at night. That's nice - and it helps :)

Bert Petersen
February 25th, 2002, 04:28 PM
There is a lot of baloney out there about this subject and some of it comes from people who supposedly know the chemistry but do not swim in the water they guard so zealously. Let's get real; chlorine is a poison. It doesn't take long for janitors and lifeguards to figure out that the water can be kept really clear and clean by just adding lots of it to the water. Then they attempt to "cancel it out" by adding a bunch of soda-ash which brings the pH up and looks good on a report. Soda-ash is poisonous too. The net result is flaming eye-balls and super-dry skin. When I swim in our pool, I suffer both. In some other pools, I don't. When I bring this to the attention of management, the attitude seems to be that it is somehow my fault !!! I would like to talk to a CPO who also trains in the pool they manage. Bert

February 25th, 2002, 05:58 PM
Hey Bert,

Well I hope you are planning to attend the T-Hills Pentathlon meet at Nike. I am not a CPO but an AFO (same difference really, but we also have a CPO on staff). The difference is I do swim in my water so you can bet it's going to be good. Unfortunately other places I have worked the water quality is poor but the upper management didn't want to spend the money to fix it, so it's not necessarily the pool tech - that's like blaming the teachers for not teaching up to date material because they have 20 year old text books. Hope to see you in a few weeks.


Bert Petersen
February 25th, 2002, 06:18 PM
I'm doing the 100's............ c ya Bert

March 3rd, 2002, 07:59 PM
I wouldn't worry about it too much. I've been swimming for many years and aside from my skin drying out in the winter due to dry air, not a big problem. I do shower again before I go to bed because of the chlorine smell which tells me there is a lot of chlorine in my skin. Just don't inhale, especially underwater.

Matt S
March 5th, 2002, 04:33 PM

Your comments sound a lot like former Surgeon General Koop. He has riffed on a couple of occaisions about fanciful theories on this chemical or that substance being "harmful" based on slender scientific evidence. The bottom line for him is that we as a society spend alot of time worrying about potentially toxic substances, and spend significant amounts of money trying to remedy their theoretical effects, when he feels the effort and money would be better spent on other health issues with much clearer and more significant impacts (e.g. obeisity, lack of exercise, tobacco use, etc.)

It's a perspective worth considering.


March 6th, 2002, 07:00 PM
Matt quotes Dr. Koop in saying that we as a society tend to get caught up in the small stuff (health-wise), while ignoring the big picture (obesity, smoking, etc.).

In general, I agree, but, in the case of the potential for long-term harm by exposure to chloramines, I am frankly surprised by the lack of real data.

Certainly, there are plausible reasons for concern (nicely discussed on Dr. Rushall's website, URL listed previously on this thread.

In addition to adult swimmers (more importantly, actually), there is the issue of young swimmers, many of whom spend up to 4 hours (sometimes more), several to many/most days per week, for 10 or more years, all while they are in a biologically vulnerable growth and development mode.

My interest in the subject was first triggered by the obvious association with asthma (in most cases, not a huge problem). But my interest really went up when I started noticing little bronze plaques, memorializing club swimmers (teenagers) who had died of cancer, affixed to walls and benches at local competition pools. Then a 15 year old girl on one of my two daughter's teams was diagnosed with (and later died from) rhabdomyosarcoma. Then a 12 year old on my other daughter's team was diagnosed with acute leukemia (fortunately now in a chemotherapy-induced complete remission). Then a 19 year old daughter of a good friend (who had been an age group and senior swimmer for 10 years) was diagnosed with a very rare type of ovarian cancer. She suffered multiple recurrences, but is now doing well following extensive surgeries.

So I wondered: Has anyone ever looked at the incidence of childhood cancer in swimmers, compared to similar groups of kids, who are not swimmers? To my surprise, I found that, no, this has never been studied and reported.

How many excess cases of childhood cancer would it take before it was "worth it" to change from chorination to ozonation? 1 per year? 10 per year? 100 per year? How many excess cases are currently attributable to swimming/training intensively in chlorinated pools? Honest people may disagree about the first of the above questions, but I don't see how anyone could disagree that it's not important to answer the 2nd question. Is there any increased risk? What is the magnitude of this increased risk? What would it cost to bring the risk down to acceptable levels?

No one knows. And this is a pity.

- Larry Weisenthal

Bert Petersen
March 6th, 2002, 07:28 PM
Thank you Larry, for a very thoughtful and thought provoking post. I too, am becoming alarmed at the obvious negative impact upon my body by obsessively excessive amounts of chlorine. ( Asthma,sore eyes, itchy skin, allergic reaction, etc.) To repeat myself, IT'S A POISON !!! Bert

March 7th, 2002, 09:26 AM
Thank you for your post Larry. I find it hard to believe that some post graduate student out there couldn't find academic support to do a well designed epidemiological study of this issue. I hope that organizations such as USMS would be willing to help survey members for such a study. Anecdotal tales are poor indicators of trends. It would be nice to have data.

March 7th, 2002, 12:40 PM
Another interesting fact in this would be to look at indoor vs. outdoor pools. Ventalation systems for Natatoriums have long been overlooked, one facility I worked at exceeded the recommendation/requirement on air movement, yet some days the air quality inside was horrible. Obviously most outdoor pools don't have this problem. Fresh air/air movement is a very importatnt factor in reducing chloramine buildup, pbut as I said it is often overlooked. I have seen people who were asthmatic swimming at outdoor pools and they were actually able to get rid of their inhalers, yet it seems indoor pools with bad air may have a tendency to trigger asthma type problems. Ozone disenfection is not without its health risks too, as is Iodine and Bromine disenfection.


March 7th, 2002, 12:51 PM
Wouldn't a study about the long term health effects be an appropriate use of our USMS Endowment Fund money? If I understand correctly, anyone can submit a proposal for USMS funding such a study to the USMS Endowment Fund's Board of Governors. The chairman is Doug Church, treasurer@usms.org . Please correct me if I'm wrong in my understanding.

Rob Copeland
March 12th, 2002, 12:15 PM
It looks like someone is already starting this study. See below:

Dear Swim Coach,

I am an environmental health scientist conducting research on the potential health effects associated with swimming pool chemicals. I am working with the American Chemistry Council, a coalition of companies that includes manufacturers of swimming pool chemicals, to improve the estimation of exposure to swimming pool chemicals. In cooperation with the U.S. Environmental Protection Agency, we have designed a telephone survey for swimming club coaches to obtain information about the amount of time amateur swimmers practice and other information relevant to swimmer's exposures to chemicals. This information may be used in future regulatory decisions about these chemicals.

Your email was provided to us by United States Masters Swimming, as a coach who is knowledgeable about swimmer's practice habits. If you would be willing to participate in the telephone survey, please reply to this email
(address is rreiss@sciences.com) with your telephone number and typical time of day that you can be reached (include time zone). Please note that the survey is completely confidential, and we will not provide your names or swim club affiliations to either the American Chemistry Council or the Environmental Protection Agency.

Thank you for your help on this important project.


Dr. Richard Reiss

March 18th, 2002, 07:33 PM
I've read some studies recently (and an article in the Washington Post from a month or two ago) linking chlorination byproducts (trihalomethanes, or THMs) to an increased risk of miscarriage in women. I think one study in California found that the risk of miscarriage rose from 7% to 15% among women who were drinking lots of tap water with relatively high THM levels. My question is, what does this mean for those of us who swim in chlorinated pools all the time?? I have seen a lot of information related to asthma and cancer, but does anyone know of any studies regarding miscarriage? It is a little frightening, especially since doctors recommend swimming as a good exercise for pregnant women (likewise for asthma sufferers of course). It may be that the risks are very slight, but this is something I am reluctant to take much risk with.

March 28th, 2002, 05:40 PM
I too saw the Washington Post article and was concerned by it since I live hear and drink that water. I'm not a chemist but from my understanding it was referring to chlorination byproducts that are the result of the chlorine in water mixing with organic nutrients, e.g. fertilizer runoff in the Potomac River in the summer time. They pump in more chlorine to deal with the contaminants and the byproduct levels can get high. It's seasonal and local and has been implicated in a lawsuit by a group of Virginia women who had miscarriages. I think the chlorine in and of itself was not factor in the miscarriages. So as long as pool water isn't similarly contaminated, it shouldn't be a problem for swimmers.

Philip Arcuni
March 28th, 2002, 06:58 PM
Well, that is just the problem. The chemistry in a pool is a lot more complicated than water with nothing but chlorine ions floating around. As any pool operator will tell you, the more a pool is used the more chlorine must be applied, and the more difficult management of pH and other factors becomes. That is because lots of organic nutrients wash off of body and hair and react with chlorine, making all sorts of nasty stuff. It is these chemicals that Larry referred to in an earlier post, and what I think is most worrisome.

March 28th, 2002, 08:02 PM
I actually work with someone who did her graduate work on THMs in treated water (THMs being the byproducts that Philip mentioned). She studied women's blood THM levels and found that they increased significantly after women took showers (but she assures me this does not mean there is any risk associated with showers!!). So water that is more highly chlorinated (like a pool...) will cause greater increases in THM levels in people exposed to it. These levels do drop after a few hours out of the water. But the THMs are there, but no one seems to know at what level they might become a measurable risk for different health effects. It seems that the acute exposure is what might be linked to miscarriages. I'm sure it is less of a risk than say smoking during pregnancy, but it is easy to get paranoid about all of these little risks adding up when you swim and take 2 showers every day... not to mention drink a lot of tap water!

April 1st, 2002, 07:39 PM
The primary fertilizer nutrient that Cl2 mixes with is amonia (nitrogen) - and produces Chloramines just like it does when it mixes with the amonia humans deposit in the pool in sweat and urine. All pools have at least some chloramines, some have a LOT. One method of removing chloramines is to "shock" or superchlorinate - ie bring the free active chlorine (FAC) level up high enough to break the bonds in any combined chlorine molecules. Many pool operators are not well versed in how to calculate the correct amount of chlorine to use in superchlorination - they either undershoot and leave most of the chloramines un touched, or overshoot and leave the pool with WAY too high a FAC level.

April 4th, 2002, 08:53 AM

This is a story from the Environmental News Network today...

LONDON — Scientists warned on Thursday that high levels of a chemical compound found in indoor swimming pools might pose a risk to pregnant women and their unborn babies.
Researchers at Imperial College London said they found levels of trihalomethanes (THMs), a by-product of chlorine, in London swimming pools that were higher than amounts found in tap water which had been associated with health problems.

"There have been some previous studies carried out with tap water where they found some effects like spontaneous abortion, stillbirths, and congenital malformations at lower levels of these byproducts," said Dr. Mark Nieuwenhuijsen, who led the study reported in Occupational and Environmental Medicine.

He added that the by-product levels are relatively high, but scientists do not know what effects THMs in swimming pools might have on pregnant women and unborn babies.

THMs are formed when chlorine, which is added to swimming pools to keep them clean, reacts with organic matter such as skin or hair.

Nieuwenhuijsen said more information is needed about THMs, which can be swallowed or inhaled, and their impact on pregnant women. In the meantime efforts should be made to reduce the levels, he said.

"The owners of swimming pools have to make sure they reduce the by-product levels because there might be a risk if they stay at this level," Nieuwenhuijsen said.

Chlorine is necessary to disinfectant swimming pools, but the scientists said levels of THMs can be reduced by making sure people clean themselves before swimming. Filtering the water can also help to keep organic matter at low levels.

The scientists examined 44 water samples from eight indoor pools in London and compared the levels of THMs found in the pools and in tap water. Although the amount of THMs varied according to the water temperature and the number of people in the pool, it was higher than levels found in tap water.

Matt S
April 4th, 2002, 07:17 PM
Let's not get carried away with overestimated the "threat" of combined chlorine. (And uncritically accepting the pronouncements of web sites without considering the credibility of the source is an easy way to work yourself into hysteria.)

What is the risk of combined chlorine? Unknown. What is the risk of a sedentary lifestyle? Pretty significant. In addition to the legion of studies showing how unhealthy a lack of regular exercise can be, a recent, widely publicized study seemed to indicate it was more dangerous than obeisity or smoking. What are the risks of other forms of exercise? They have their problems too.

My point is that you're kidding yourself if you think you can avoid exposure to all toxins and carcinogens. But, as George Burns once said in response to the questions, "how does it feel to be over 90," that's not bad, considering the alternative.


Philip Arcuni
April 4th, 2002, 07:32 PM
It also doesn't hurt to encourage showering before swimming, filter pool water, ensure adequate air circulation, or using the best water purification system available.

It also does not hurt to provide motivations for doing so, or to swim in the pool that is best maintained. I have, in the past, complained to the pool manager, avoided pools that I thought were poorly maintained, and swum outdoors, rather than indoors, if possible.

April 4th, 2002, 08:40 PM
Matt S. I completely agree with you. Most of us have much more exposure to greater risks in our everyday lives. Second hand smoke I am sure is much worse. But I haven't seen much research on the acute effects of THMs and I would like to see some. I used to work for the EPA and I know how many things are out there in our air and water that are not even regulated simply because we don't know enough about them. I'm not paranoid, I swim every day and even drink tap water occassionally, but I think anything that *might* cause an increased risk of miscarriage is a very scary thought to women trying to conceive. Won't stop me from swimming though... better yet, another good argument for open water swimming...

old dog
January 7th, 2004, 08:09 PM
This is an old thread. Does anyone know of any new studies
re: asthma and swimmers..esp. kids??

March 15th, 2004, 10:07 AM
In regards to chlorine.

I recently read that chlorine kills the bacteria in your body- healthy and unheathly. The article even states that chlorine in your shower is a culprit which must be much less than the pool chlorine level.

I wonder what any swimming doctors think about this.

March 15th, 2004, 03:54 PM
Emmett, here is the formula used by CPO's:

Total Available Chlorine(TAC) - Free Available Chlorine(FAC) = Combined Available Chlorine(CAC) (Also known as Chloramines, Chloramines are the nasty smellers when you walk into a facility) Multiply this number X 10 = Adjustment(Amount needed to reach Breakpoint) This number is then put into a formula to tell you how much chlorine to add to the water to reach the breakpoint. These numbers differ depending on what type of chlorine you're using and how much water you're treating. If any one wants the rest of the formula, let me know.

By the way, I am also one of those CPO's that swim in his own pool. Try to keep it as straight as possible!:D

March 15th, 2004, 04:25 PM
If you think a lap pool is scary - then you don't want to know about your jacuzzi/hot tubs.
If the pool you swim at has an ozone system then you don't have to worry so much about chloramines (not only does the ozone disenfect but it also breaks down/destroys chloramines).
Lastly for indoor pools your HVAC system is very importatnt - hopefully the air circulation system isn't at the bottom of the required scale (more air movement is better).

March 15th, 2004, 08:55 PM
Ok a swimming doctor (family practitioner, not a super sub specialist or toxicologist)

I read over all the posts and searched some sites (like the CDC and FDA etc) for research on this.

Everything really focuses on chlorine gas as a respiratory irritant, with little research on long term, low level exposure. If you have asthma, this may cause you problems. However, let your doctor know and most likely your medicines can be adjusted to help prevent any asthma complications associated.

Some important things to remember. Chlorine is very reactive. It sure does cause some damage, but only very quickly and locally. Your body actually USES its own natural chloride ions in specific places to help manage things like mucous (especially in the respiratory system). There are 3 main sites I can think of that chlorine the swimming pools could theoretically cause some problems.

First is the eyes. Obvious: wear your goggles.

Next is the surface area of your body. Hair: makes it tougher, strawlike and funky. Use a conditioner or something like that to remove and or block chlorine; also a swim cap. Your skin can definitely be affected, but because of the cool way our skin is put together, it really should not be able to penetrate the skin and cause any damage internally. Thus, you CANNOT kill any beneficial bacteria internally this way. You can (and will) get a local skin irritation depending on length of time in the pool, other existing skin conditions (like eczema), etc. These can be minimized or prevented by showering before getting in the water (then the little microscopic areas of your skin are full of water with less chlorine than the pool already) and using a mild lotion after (not before, it will strip clean off) getting out of the water. Shower again, however, to replace the chlorinated water before lotion.

Sorry for the length of this.

Next is respiratory. I could not find any data on long term exposure to low level chlorine levels. However, there could in theory be a chance of causing damage to some of the supporting structure of the alveoli. I must hasten to add that one of the reasons I started swimming for fitness is that the healthiest old folks I see as patients are over represented as swimmers. These are 80+ year olds whose lungs sound awesome. So weak anecdotal evidence: I doubt it is a worry.

Finally (oops I lied I came up with 4 sites) is accidental swallowing. This would be my guess as to where the funky organic chlorine molecules came from in the study cited above. Ironically enough, chlorine itself would be unlikely to cause much problem in the stomach, and is going to get neutralized as soon as it hits the small intestine anyway. However, weird organic chlorine compounds could in theory survive some digestion. Don't think about this too much or you'll be scared to get any water in your mouth next time.

Oh yeah: cancer is unlikely a risk (although never impossible), because cancers really need to come from DNA damage, and chlorine has usually already reacted to your cell membranes, epidermis, etc and "burned itself out" before it could get close to your DNA. BUT: I couldn't find much research on this, so this is largely supposition.

Summary: Swimming is great and overall probably better for you than any other exercise, even when chlorine is involved. My opinion.

March 15th, 2004, 08:58 PM
Oh and I stay away from hot tubs/jacuzzis -- the warmth really grows a lot of little beasties, even in the high chlorine levels.

March 16th, 2004, 12:26 PM
i tend to itch too if the chlorine levels are up,also my eyes still get sore even with goggles,i have to re shower when i get home .chlorine however does chemically remove greater nasties than it creates..the skin has natural oils and too much bathing removes these oils,this makes you itch..i too shower before and after entering the pool

old dog
January 4th, 2006, 03:14 PM

January 1st, 2007, 04:12 AM
In the course of preparing materials for the Swimming Science Journal, I came across the following articles concerning chlorinated pools. Abstracts of contents and appropriate comments are included below. Please read the discussion points and articles that follow the abstracts.

Exercising competitive swimmers absorb toxic levels of chlorine products in the course of a training session.
Training two or more times a day will not allow the toxins to be completely cleared from the body in most swimmers.
Children inhale more air per unit of body weight than mature persons, and have lesser developed immune and defense systems.
Young children absorb relatively greater amounts of toxins than older swimmers and therefore, are at greater risk.
In hyper-chlorinated pools, even dental enamel can be eroded because of the increased acidity in swimmers in training.
Exercise intensity and number of sessions increase the toxic concentrations in competitive swimmers.
Greater toxin absorption occurs through the skin than through breathing. However, the breathing action alone is sufficient to cause hypersensitivity and "asthma-like" respiratory conditions in at least some swimmers. The percentage of asthma-like symptoms in swimmers that is attributable to exposure to chlorinated hydrocarbons versus being unrelated to chlorine exposure is presently unknown. This is an area clearly deserving of further research.
Overchlorination is particularly hazardous to the health of swimmers.
Bernard, A., Carbonnelle, S., Michel, O., Higuet, S., de Burbure, C., Buchet, J-P., Hermans, C., Dumont, X., & Doyle, I. (2003). Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations with the attendance at indoor chlorinated swimming pools. Occupational and Environmental Medicine, 60, 385-394.
This study assessed whether exposure to nitrogen trichloride in indoor chlorinated pools may affect the respiratory epithelium of children and increase the risk of some lung diseases such as asthma.
Healthy children (N = 226), were measured for serum surfactant associated proteins A and B (SP-A and SP-B), 16 kDa Clara cell protein (CC16), and IgE. Lung specific proteins were measured in the serum of 16 children and 13 adults before and after exposure to NCl3 in an indoor chlorinated pool. The relation between pool attendance and asthma prevalence were studied in 1881 children. Asthma was screened with the exercise induced bronchoconstriction test (EIB).
Pool attendance was the most consistent predictor of lung epithelium permeability. A positive dose-effect relation was found with cumulated pool attendance and serum SP-A and SP-B. Serum IgE was unrelated to pool attendance, but correlated positively with lung hyperpermeability as assessed by serum SP-B. Changes in serum levels of lung proteins were reproduced in children and adults attending an indoor pool. Serum SP-A and SP-B were significantly increased after one hour on the poolside without swimming. Positive EIB and total asthma prevalence were significantly correlated with accumulated pool attendance indices.
Implications. Regular attendance at chlorinated pools by young children is associated with an exposure-dependent increase in lung epithelium permeability and increase in the risk of developing asthma, especially in association with other risk factors. It is postulated that increased exposure of children to chlorination products in indoor pools might be an important cause of the rising incidence of childhood asthma and allergic diseases in industrialized countries. Further epidemiological studies should be undertaken to test this hypothesis.

Aggazzotti, G., Fantuzzi, G., Righi, E., & Predieri, G. (1998). Blood and breath analyses as biological indicators of exposure to trihalomethanes in indoor swimming pools. Science of the Total Environment, 217, 155-163.
In this article, exposure to trihalomethanes (THMs) in indoor swimming pools as a consequence of water chlorination was reported.
Environmental and biological monitoring of THMs assessed the uptake of these substances after a defined period in competitive swimmers (N = 5), regularly attending an indoor swimming pool to train for competition during four sampling sessions. Analyses were performed by gas-chromatography and the following THMs were detected: chloroform (CHC13), bromodichloromethane (CHBrC12), dibromochloromethane (CHBrsC1) and bromoform (CHBr3). CHC13 appeared the most represented compound both in water and in environmental air before and after swimming. CHBrC1w and CHBr2C1 were always present, even though at lower levels than CHC13, CHBr3, was rarely present. In relation to biological monitoring, CHC13, CHBrC12 and CHBr2C1 were detected in all alveolar air samples collected inside the swimming pool. Before swimming, after one hour at rest at the pool edge, the mean values were 29.4 +/- 13.3, 2.7 +/- 1.2 and 0.8 +/- 0.8 micrograms/m3, respectively, while after spending one hour of swimming, higher levels were detected (75.6 +/- 18.6, 6.5 +/- 1.3 and 1.4 +/- 0.9 micrograms/m3, respectively). Only CHC13 was detected in all plasma samples (mean: 1.4 +/- 0.5 micrograms/1) while CHBrC1x and CHBr2C1 were observed only in few samples at a detection limit of 0.1 micrograms/1. After one at rest, at an average environmental exposure of approx. 100 micrograms/m3, the THM uptake was approx. 30 micrograms/h (26 micrograms/h for CHC1c, 3 micrograms/h for CHBrC12 and 1.5 micrograms/h for CHBr2C1). After one hour of swimming, the THM uptake was approximately seven times higher than at rest: a THM mean uptake of 221 micrograms/h (177 micrograms/h, 26 micrograms/h and 18 micrograms/h for CHC13, CHBrC12 and CHBr2C1, respectively) was evaluated at an environmental concentration of approx. 200 micrograms/m3.
Implication. Training for swimming in a poorly ventilated indoor swimming pool has the potential to cause illness through breathing undesirable concentrations of mainly chloroform.

Lindstrom, A.B., Pleil, J.D., & Berkoff, D.C. (1997). Alveolar breath sampling and analysis to assess trihalomethane exposures during competitive swimming training. Environmental Health Perspectives, 105(6), 636-642
Alveolar breath sampling was used to assess trihalomethane (THM) exposures encountered by collegiate swimmers during a typical 2-hr training period in an indoor natatorium.
Breath samples were collected at regular intervals before, during, and for three hours after a moderately intense training session. Integrated and grab whole-air samples were collected during the training period to help determine inhalation exposures, and pool water samples were collected to help assess dermal exposures.
Resulting breath samples collected during the workout demonstrated a rapid uptake of two THMs (chloroform and bromodichloromethane), with chloroform concentrations exceeding the natatorium air levels within eight minutes after the exposure began. Chloroform levels continued to rise steeply until they were more than two times the indoor levels, providing evidence that the dermal route of exposure was relatively rapid and ultimately more important than the inhalation route in this training scenario. Chloroform elimination after the exposure period was fitted to a three compartment model that allowed estimation of compartmental half-lives, resulting minimum blood borne dose, and an approximation of the duration of elevated body burdens. It was estimated that dermal exposure route accounted for 80% of the blood chloroform concentration and the transdermal diffusion efficiency from the water to the blood was in excess of 2%. Bromodichloromethane elimination was fitted to a two compartment model that provided evidence of a small, but measurable, body burden of this THM resulting from vigorous swim training.
These results suggest that trihalomethane exposures for competitive swimmers under prolonged, high-effort training are common and possibly higher than was previously thought and that the dermal exposure route is dominant. The exposures and potential risks associated with this common recreational activity should be more thoroughly investigated.
Implication. In this study the greater importance of transdermal (via the skin) uptake of chlorinated hydrocarbons compared to the respiratory route is demonstrated. This indicates that improved ventilation alone will not have a major impact on exposure to these materials because it is being immersed in the liquid that is the greatest threat. In contrast, ozonation allows markedly reduced levels of chlorine in the pool water.

Drobnic, F., Freixa, A., Casan, P., Sanchis, J., & Guardino, X. (1996). Assessment of chlorine exposure in swimmers during training. Medicine and Science in Sports and Exercise, 28(2), 271-274.
The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been recently reported. Chlorine, a strong oxidizing agent, is an important toxic gas that a swimmer can breath during training in chlorinated pools.
Measurements of the chlorine concentration in the breathing zone above the water (< 10 cm) were obtained randomly during five nonconsecutive days in four different swimming pool enclosures. The mean level in all the swimming pools was 0.42 +/- 0.24 mg/m3, far below the threshold limited value (TLV) of 1.45 mg/m3 for the work places for a day of work (8 h). The TLV could be reached and even exceeded if we consider the total amount of chlorine that a swimmer inhales in a daily training session of two hours (4-6 g) compared with a worker during eight hours at the TLV (4-7 g). Low correlation was observed with the number of swimmers in the swimming pool during the measurements (0.446) and other variables as the water surface area of the pool, volume of the enclosure, and the chlorine-addition system in the swimming pool. A low turnover rate in the air with an increase of chlorine levels through the day was observed in all pools.
The concentration of chlorine in the microenvironment where the swimmer is breathing is below the TLV concentration limit, but nevertheless results in a high total volume of chlorine inhaled by the swimmers in a given practice session.
The possible role of chlorine in producing respiratory symptoms in swimmers needs further investigation.
Implication. Even though chlorine concentrations in a pool environment are at acceptable "safe" levels, it is a swimmer's exercising that produces abnormal levels of exposure to this toxin.
There has not been sufficient research to even begin understanding the health effects of this repetitive exposure.

Cammann, K., & Hubner, K. (1995). Trihalomethane concentrations in swimmers' and bath attendants' blood and urine after swimming or working in indoor swimming pools. Archives of Environmental Health, 50(1), 61-65
The influence of working or swimming in indoor swimming pools on the concentrations of four trihalomethanes (haloforms) in blood and urine was investigated. Different groups (bath attendants, agonistic swimmers, normal swimmers, sampling person) were compared.
The proportions of trihalomethanes in blood and urine correlated roughly with those in water and ambient air. Higher levels of physical activity were correlated with higher concentrations. Within one night after exposure in the pool the blood concentrations usually were reduced to the pre-exposure values. Secretion of trichloromethane in urine was found to be less than 10%.
Implication. Exercising in a chlorinated pool increases the levels of assimilation of chlorine related gases. The greater the amount of exercise, the greater the concentrations. Thus, hard training swimmers are at greater risk than more sedentary pool attendants and coaches.
It takes at least one night for absorbed substances to be removed. If insufficient time exists between training sessions the possibility of toxic build-up is real.

January 1st, 2007, 08:17 PM
Are there any chemistry whizes out there that can answer this?....Are Chlorine and Dioxin simillar enough to cause the same effects in the human body?? Dioxin has been proven to cause endometriosis in women. It has also been linked to many other health problems....just curious!

January 1st, 2007, 08:38 PM
It takes at least one night for absorbed substances to be removed. If insufficient time exists between training sessions the possibility of toxic build-up is real.

Ok what does one night mean? 8 hours? 22hours? Or does something happen when you're sleeping to rid the body of toxins?
Just thinking if you're doing 2 a day at 5am and 5pm...is there a "night's worth" of time in there?

January 2nd, 2007, 07:41 PM

Well all of this depends on the pool you swim in!

I swim in Christchurch New Zealand. Heated indoor and chlorinated!

I can smell the chlorine the next day from my skin, and this maybe after 2 showers with complete washes with soap.

I also have cancer and I am fighting this from every direction I can. I am very fit, however I now understand cancer. I simply cant take the risk of adding to the long list of chemicals we are already exposed to.

Don't worry I will beat it, however I found the above study in my search for answer's.

If did not have cancer and lead a life that assisted in my bodies own immune system to fight against cancer buildup then I would continue to swim as I believe the benefit outweighs the risk.

It's all in moderation, however the lower the chlorine level the better!!

April 9th, 2008, 12:10 AM
This is an old thread, wonder if there are folks, like me, interested in this topic? Any new development? If you swim 7 days a week, 1 hour each time, in a heavily chlorinated pool, does it take months or years for the serious harm to be done? The place where I swim, the pool is many floors up on top of the building (indoor pool), but you can already smell very strong chlorine at the building entrance on street level.

April 9th, 2008, 06:16 AM
This is an old thread, wonder if there are folks, like me, interested in this topic? Any new development? If you swim 7 days a week, 1 hour each time, in a heavily chlorinated pool, does it take months or years for the serious harm to be done? The place where I swim, the pool is many floors up on top of the building (indoor pool), but you can already smell very strong chlorine at the building entrance on street level.

I'm wondering if the street-level chlorine odor is an artifact of how the building is vented, espec if it is an older building.

I'm definitely not an expert, but my take on the above-referenced studies is that you probably do not have the type of exposure that would cause serious harm in a normal, healthy person. The one study I read on exposure in elite swimmers looked at those who swam exhaustively many hours a day. Perhaps it would help to reread the abstracts put up by "daggles69" and note the study groups: "competitive swimmers," "intense training," "two hours" (or more) per day, in a poorly ventilated pool area. If you are highly concerned or have a predisposing condition, you may be able to find a pool that does not use chlorine; the newer ones are more commonly using alternatives.

April 9th, 2008, 09:35 AM
I'm wondering if the street-level chlorine odor is an artifact of how the building is vented, espec if it is an older building.

The odor definitely comes from the pool. The building is very new. I do hope it takes years and years of intense training for the harm to be done. OTH given the very strong smell in this place perhaps a few months is bad enough. The smell of chlorine on my skin remains the next day like daggles69.

April 10th, 2008, 03:27 PM
I have found that showering BEFORE entering the pool greatly decreases the chlorine smell I carry around after swimming. Whether this indicates a decreased absorption of chlorine or is strictly anecdotal, I don't know. There may be no changes in health consequences but at least I don't smell like a washing machine after my wife washes the whites!

Redbird Alum
April 10th, 2008, 03:54 PM
We all have to die from something... not sure if the worms will like the chlorine cologne.

May 25th, 2008, 05:11 PM
I'm writing an article on the safety of swimming pools, touching on some of the dangers of chlorine disinfecting products. In researching this, I came across your website and read some of the concerns expressed, by athletes, aquatics directors, and parents, having to do with various potential or imagined threats. My impression before this was that few people are even aware of these issues of asthma, respiratory ailments, skin rashes, eye infections, etc. etc.

In the aquatics field, do people think this is a serious issue that demands more study? Are parents of athletes in training, coaches, and swim clubs aware of these issues?

Let me know if you have any perspectives on this you'd like to share.

F Lyman

May 25th, 2008, 07:13 PM
When I swam competitively there were 4 kids I knew whose doctors recommended competitive swimming because the kids had asthma. During the years I swam with them none of them had an asthma attack or carried an inhaler. AFAIK, they had no other issues.
While swimming 2x/day as well as having meets on weekends, no one I knew suffered any skin, eye, respiratory or other ailments. Everyone was, and continues to be, as healthy as the proverbial horse.
That said, I live in San Diego and always swam in outdoor pools. I don't know if that makes a difference...

**and a funny P.S....our family dog drank exclusively from our pool. She refused to drink out of a dog dish. The dog was never sick, died at 16, and had the whitest doggie teeth you have ever seen.

May 26th, 2008, 11:40 AM
As usual some worry about how healthy life styles or endeavors might "not" be healthy. I got criticized for running long distances, even by a cardiologist! The sedentary people and even the overweight are sometimes critical and try to find some excuse for not doing exercises. Not your case, I hope. Back in the late 60s the swimming pools were loaded with chlorine, and we didn't have any eye protection. No one ever got hurt or had any health problems even while doing extensive practice in the pools. Nowadays, pools have pretty much a mixture in their sanitation process, using a blend of chemicals that one hardly perceives. I will add that even the sun exposure problem in outdoor pools is exaggerated. As an aside, there are many pool sanitation methods that do not use chlorine.

May 28th, 2008, 02:49 AM
There's no doubt that too much chlorine exposure is bad. If you have access to a lake or ocean nearby that would help mix it up every once in a while. Also to help balance the chlorine absorbed into your system through your skin there are herbs and minerals you can take (balance your own pH out, just like the pool).

May 28th, 2008, 04:29 PM
As the original poster of this thread, I cheer you on with your studies. Knowledge is power and we don't seem to have a lot of science on this. My gut tells me the safety question is highly variable depending on the composition of the "soup" we swim in, the external environment in the pool area, time spent in contact, pre-shower vs. no shower, de-chlorinating rinses and lotions, and on and on. I still believe the health benefits outweigh the risks but vigilance is warranted. I'm sure running is a very healthy activity but I wouldn't recommend doing it on the interstate or in Chernobyl. Besides, you might get something published that would be of interest to somebody. I had a professer once that said "The definition of a drug is any compound which, upon injection into a laboratory rat, generated a paper". Good Luck!

May 28th, 2008, 05:43 PM
Also to help balance the chlorine absorbed into your system through your skin there are herbs and minerals you can take (balance your own pH out, just like the pool).

Such as?

May 28th, 2008, 06:22 PM
I have a copy of this article,from the journal "Human and Ecological Risk Assessment", if anyone wants it. Send me your e-mail address.

"Human and Ecological Risk Assessment"
2006, Volume 12, Number 1, February
Development of Factors for Estimating Swimmers’ Exposures to Chemicals in Swimming Pools - 139
Richard Reiss, Gerald P. Schoenig, and Gary A. Wright

The U.S. Environmental Protection Agency (USEPA) has developed a model to estimate chemical-specific exposures to swimmers following pool treatments. This model is called SWIMODEL. The model was first introduced in 1996, and the USEPA has made refinements to the model over the last decade. One of the most significant parameters in this model is the duration of exposure. Unfortunately, there was no reliable source of data for these exposure durations, so highly conservative estimates were used in the earlier version of SWIMODEL. In order to address this data deficiency, a telephone survey of competitive swimming coaches was conducted to provide data for the refinement of the SWIMODEL. The survey collected data on practice durations and other factors that are potentially relevant to swimmer exposures. Two different surveys were developed. The first survey was designed for coaches of amateur swim club teams, and the second survey was for collegiate coaches. The survey found that the average practice durations for youth, adult Masters, and collegiate teams were 9.1, 6.4, and 17.0 hours/week, respectively. The use of these data to estimate acute, chronic, and lifetime exposures is discussed. The data developed in this study were used to update the exposure duration and frequency estimates in SWIMODEL for competitive swimmers based on survey responses. The survey was also used to determine the percentage of competitive swimmers that wear eye goggles and other protective gear, and to supplement other measurements of the incidental water ingestion of competitive swimmers.

Also, I found this on the EPA web site:
Swimmer Exposure Model (SWIMODEL) User's Guide

October 24th, 2013, 04:26 PM
There are studies that show a link between pool cleaning agents like chlorine and bromine interacting with organic material such as hair, skin, sweat, and urine, to trigger DNA markers (genotoxicity?). Here's one of these. I too swam for 45 years, then got bladder cancer (treated successfully without bladder removal) but intend to go back in but perhaps in pools that use other ways to clean it.


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Chemicals in Indoor Swimming Pools May Increase Cancer RiskSep. 14, 2010 — Swimming in indoor chlorinated pools may induce genotoxicity (DNA damage that may lead to cancer) as well as respiratory effects, but the positive health effects of swimming can be maintained by reducing pool levels of the chemicals behind these potential health risks, according to a new study published in a set of three articles online September 12 ahead of print in the peer-reviewed journalEnvironmental Health Perspectives (EHP). This study is the first to provide a comprehensive characterization of disinfection by-products (DBPs) in an indoor pool environment and the first to study the genotoxicity of exposure to these chemicals among swimmers in an indoor chlorinated pool.
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DBPs form in pool water from reactions between disinfectants such as chlorine and organic matter that is either present naturally or is introduced by swimmers, such as sweat, skin cells, and urine. Previous epidemiologic studies have found an association between exposure to DBPs in drinking water and risk of bladder cancer, and one such study has found this association for dermal/inhalational exposure such as occurs during showering, bathing, or swimming.
The new study details a comprehensive investigation of DBPs and mutagenicity of water samples collected from two indoor pools, one disinfected with chlorine, the other with bromine. In addition, short-term changes in biomarkers of genotoxicity and respiratory effects were studied in swimmers who swam in the chlorinated pool. No previous studies have combined investigations of the mutagenicity (ability to cause permanent DNA mutations) of pool water with a comprehensive chemical characterization of the water and studies of human exposures, the authors stated.
Evidence of genotoxic effects were seen in 49 healthy adults after they swam for 40 minutes in the chlorinated pool. Specifically, researchers found increases in two genotoxicity biomarkers relative to the concentration of the most common types of DBPs in exhaled breath, which were used as a measure of the swimmers' exposures. The biomarkers that increased were micronuclei in blood lymphocytes, which have been associated with cancer risk in healthy subjects, and urine mutagenicity, which is a biomarker of exposure to genotoxic agents.
Detailed measurements were also made of the most common exhaled DBPs (trihalomethanes) in air around the pool and in exhaled breath of the swimmers before and after swimming. Researchers measured several biomarkers of respiratory effects after swimming and found changes in only one -- a slight increase in serum CC16, which suggests an increase in lung epithelium permeability. This result was explained by the effects of exercise itself as well as exposure to DBPs. Further research is needed to sort out the clinical relevance of this acute change, the researchers stated.
In addition, the authors identified more than 100 DBPs in the pool waters, some never reported previously in swimming pool water and/or chlorinated drinking water. In vitro assays showed that the swimming pool water was mutagenic at levels similar to that of drinking water but was more cytotoxic (can kill cells at a lower concentration) than drinking water.
The human exposures studied were short-term, and further investigations of genotoxic and respiratory effects of longer-term exposures are needed, the authors stated. Also noted was a need for further research on an array of swimming pools under various conditions of maintenance and use, as well as more complete evaluations of the uptake and potential effects of the wide range of compounds present in pool water. These are preliminary results that should be confirmed in studies with larger sample sizes.
This work was supported by the Spanish organizations Plan Nacional and Fondo de Investigación Sanitaria, Instituto de Salud Carlos III; and also by the U.S. Environmental Protection Agency.