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Thread: Safe swimming with elevated chlorine

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    Default Re: Safe swimming with elevated chlorine

    I doubt anyone will say "yes, definitely, swim in 20ppm, no problem, you'll never get sick". These kinds of absolutes rarely exist (notice I say rarely instead of never). Never say never, that's the first rule of lawyer club!!

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    Default Re: Safe swimming with elevated chlorine

    Someone posted this on another thread recently. Seems like a really good article on the relationship of CYA and chlorine. It explains ORP (oxidation reduction potential) and references academic studies on this subject.

    I was curious earlier whether the bad effects of high chlorine were somehow reduced in a high CYA pool, so I started a thread on the subject.

    I am a believer in Ben's Best Guess chart and dose my pool accordingly, but I also appreciate the questioning of fcfrey. It contributes and keeps us honest.

    edit: ...and prompts a pretty good post from PoolDoc.

    -Jim
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    Exclamation Re: Safe swimming with elevated chlorine

    Hi All;

    First, I am moving this thread to the China Shop -- which is NOT an indication that I disapprove of the question, or the discussion. It simply reflects that this thread is a debate about somewhat theoretical issues, rather than an answer to a practical question.

    I'm sure it's my fault, but there seems to be a perception of the China Shop as the near equivalent of the Hall of Shame. Thhere's no such equivalence in my mind. My intention is that the China Shop is where answers should be hashed out, where a clear one doesn't exist, OR where someone is unconvinced. To some degree, both issues exist within this thread.

    ----------------------------------------------------------------

    However, to return to the original issue . . .

    The cited article from the Green Guide is actually one of the best and most informative of the citations mentioned above. The others seem to be 'me-too' articles, without footnotes or reference to research. To the best of my knowledge, the Green Guide article accurately, but incompletely, reports on some issues regarding chlorination. Unfortunately, the articlet fails to place that information within the appropriate context. I don't know that this was a deliberate effort on the part of the authors, or an oversight on their part. But have seen a consistent lack of 'contextualization' in articles by environmentalists about chlorine. Many of them have a structure somewhat like this:

    The sky is falling, in Antartica, in maybe 600 years.

    Still, I should quickly add, that the article is FAR less biased and FAR more accurate than what I've become accustomed to, when reading articles about chlorine by 'greenies'.

    Let me see if I can address the issues in the article.

    It is true that chlorine reacts badly with many organics, to form the sort of chemicals described. But several important points are omitted!

    Dioxin and furans have NOT -- to the best of my knowledge -- been identified as forming when relatively clean water (like pool water) is chlorinated. Rather, they form when industrial waste or process streams are chlorinated. Thus, while these chemicals may (and there's considerable doubt about just how toxic dioxins, in particular, really are!) be an important issue, they are not, to the best of my knowledge, a pool issue. To omit this information is fundamentally misleading.

    However, it is true that some noxious chlorinated organics do form when pools are chlorinated. It's also true that there's a growing body of evidence that indoor pools are increasingly not so good for asthmatics, and may even lead to the emergence of asthma in previously healthy individuals. This is an issue that is very important to me. My oldest son nearly died of asthma when he was 3 years old. Now, at 19, his asthma is very well controlled, but he must take several medications daily. He began swimming at 4 or 5 years old, as part of regimen we stayed on, to protect his health. At 15, he was an elite distance swimmer, and was approaching sub-17 minute mile times. But, at 16 he dropped out of USS swimming, because the affects of the asthma prevented him from moving to the next level in competition. Now, at 19, he teaches swimming 4 days per week and swims 3 - 5 per week with the local master's group. He recently entered his first open water competitive swim, and was the overall winner of the 4 1/2 mile event, and the lack of chlorinated organics in the air definitely helped his performance.

    Anyhow, I've pursued information about swimming, pool room IAQ, and respiratory effects for years for reasons that had little to do with the PoolForum. Unfortunately, that much of that data is of very poor quality. Often, the studies are done EITHER by physicians or ELSE by engineers. The result tends to be that the studies either have very good data on physiologic effects of exposure to particular pool environments OR they have good data characterizing the chemical and environmental parameters of particular pool environments, but not both. The doctors tend to do a poor job of quantifying what's in the water or the air, often lumping all oxidizing halogen compounds under the label, "Chlorine". And, the engineers tend to do a poor job examing the health effects of exposure, and fail both to establish control groups and to carefully and accurately assess both pre- and post-exposure subject health status. All the analyses tend to suffer for a lack of specificity in identifying the various species of DBP present, even though such specificity is very important to understanding the risks and reducing the problem contaminants. The barrier is that exact analysis of these compounds is both difficult and expensive.

    Going futher, the "Green Guide" observes that some of these DBP's (Disinfection By-Products) "biodegrade very slowly". While this may, or may not be true, it is stunningly IRRELEVANT to pool operators and swimmers, since biodegradation NEVER occurs in properly operated swimming pools! Properly operated pools have no microbes present to biodegrade anything, either slowly or rapidly!

    Nevertheless, I know from my own son's experience, and from that of many other asthmatic swimmers, that the IAQ (Indoor Air Quality) of many competitive pools adversely affected him, and other swimmers as well. With certain pools -- particularly including the Tracy Caulkins pool in Nashville -- we learned to keep him entirely out of the facility, except when he had to be there for his events. Even then we gave up on the 4th day for 4 day meets: the air quality would be so bad that his performance was always poor. His best times always came at certain pools that had very good IAQ, such as the old pool at the University of Tennesse at Knoxville.

    But, again, the "Green Guide" omitted a crucial piece of data. While it is true that there's growing evidence that chlorinated pools may be adversely affecting respiratory functions, especially among asthmatics, this data UNIVERSALLY applies EXCLUSIVELY to INDOOR pools!

    To the best of my knowledge, there is NO EVIDENCE whatsoever of similar effects from swimming in outdoor pools!

    Indoor pools, as I have said many times before, are an entirely different matter than outdoor pools, and much harder to 'do right'. For years now, I've deliberately avoided discussions here of managing indoor pool chemistry, for precisely that reason. I have, personally, years of experience with such pools. And it's precisely that experience that has convinced me that there are no 'easy answers' for indoor pool operators, corresponding to the answers I can offer outdoor pool operators.

    The bottom line is that there are problems with DBP's and THM (Tri-Halo-Methanes) which form when indoor pools are chlorinated. There is a growing body of evidence that these complex halogenated volatile compounds adversely affect swimmer respiratory function. BUT, this data has virtually NO relevance for the PoolForum user population, which is almost exclusively composed of owners of OUTDOOR RESIDENTIAL pools, which not only have unlimited 'ventilation' with fresh air, but which are further exposed to solar UV, and subject to photolytic degradation of those DBP's. Both chloroform and bromodichloromethane are known to be photolytically degraded; my guess is that many of the other DBP's are as well. This of course will dramatically affect any potential *build-up* of these compounds in *outdoor* pools.

    In the "Green Guide" article, you may recall that the question the author, Carmela M. Federico, purports to answer was this: "Is Chlorine Safe For My Pool?". She proceeds to report, more or less accurately, on hazards that may result from the chlorination of *industrial process or waste streams* and *indoor* pools. Since less than 1% of pool owners have indoor pools, and since 0% of pool users are swimming in either waste or process streams . . . she really didn't have anything to say of relevance for the 99% of pool owners who have *outdoor* pools.

    More pointedly, even in what she did say, she said NOTHING about what SPECIFIC levels of chlorine were safe or unsafe, which was the heart of the question posed by the OP.

    Even more negligently, she recommends, in rather vague fashion, trying to induce health departments to drop chlorine, but fails utterly to consider the health risk of doing so! This is seriously irresponsible. As is disgustingly common in such articles, the author doesn't address, even briefly, the reasons chlorine is added to the water in the first place, nor does she acknowledge the huge and unprecedented IMPROVEMENT in public health brought about by the chlorination of water. Please keep in mind that it is arguable that chlorination of drinking water has saved more lives than the entire medical care system!

    Her recommendation to use other, vaguely specified, non-chlorine methods has a very definite -- and not particularly small -- risk to the health of those using waters treated with such methods!

    So, even though many of the details in her article were accurate, the overall picture she presented was so degraded by a lack of context, and by magician-like misdirection, as to create an almost completely false representation of the situation faced by most pool owners!

    . . . continued next


    Ben
    "PoolDoc"

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    Default Re: Safe swimming with elevated chlorine

    . . . continued from above

    The other articles were much less informative, and mostly contained 'me-too' recitations of the standard pool industry wisdom. Most of what I say was correct. However, the specific chlorine level guidelines listed were either unsupported, or based on WAG's (Wild A## Guesses). Apparently so was the original (circa 1970) EPA standard of 3 ppm, according to reports I've gotten from people who were sitting at that table. What was reported to me was that they based their decision on the fact that most public pools, then using gas chlorine injected into pool water containing no stabilizer, were struggling to maintain 1 ppm, but that those that did were mostly achieving what was then perceived to be adequate sanitation. The 3 ppm level was reportedly chosen as been sufficiently greater than the common 1 ppm, to offer an adequate range of operation. The problem was that this 3 ppm standard is NOT appropriate for the stabilized pool operations that was just beginning to be widespread at that time.


    By the way, I found one very informative analysis posted on the web, in checking out some things for this post. In particular, it may be right up Waterbear's alley. Here's where I found it: http://almashriq.hiof.no/lebanon/600...ar-water/idrc/

    That's all for now . . .

    Ben
    "PoolDoc"

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    Default Re: Safe swimming with elevated chlorine

    Quote Originally Posted by fcfrey
    Most of what I have read says below 5 ppm otherwise chlorine can be absorbed through the skin and is hazardous to your health.
    Just one correction to your comment: as far as I know, it is entirely FALSE that "chlorine can be absorbed through the skin". Rather there is evidence that some halogenated compounds -- which may, or may not be present in pools -- can be so absorbed.

    But keep in mind that salt is a halogen compound, as is your pool liner, as are many other ubiquitous materials.

    Ben

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    Default Re: Safe swimming with elevated chlorine

    Quote Originally Posted by PoolDoc

    By the way, I found one very informative analysis posted on the web, in checking out some things for this post. In particular, it may be right up Waterbear's alley. Here's where I found it: http://almashriq.hiof.no/lebanon/600...ar-water/idrc/

    That's all for now . . .

    Ben
    "PoolDoc"
    Very intersting reading. The germacidal properties of sunlight and UV are well known. The most pertinent things I got from the paper are some things that we already know....Sunlight (mostly UVB) destroys simple halogens and might also destroy combined ones. Interesting side note, As I've said before I've kept aquariums for many years and when choramines became commen in drinking water treatement to prevent the formation of trihalomethanes it became a real pain in the a** to treat the water to get rid of the chloramines and the chorine. When chlorine by itself was used it only took a bit of sodium thiosulfate to destroy the chlorine and make the water safe for the tank. When chloramines were in the water we had to resort to breakpoint chlorination first and then thiosulfate....or as an alternative, it was determined that leaving the water exposed to direct sunlight for a day or two would destroy most of the choramines. OTO was the recommened test to determine when the chlorine was gone in either method. Not sure who came up with the sunlight method but it was pretty popular in my circle in the late 70's. It was discussed at the Marine Aquaruim Society that I belonged to at meetings.

    Getting back to the article. From my understanding it's main thrust was what they call the 'Halisol" method which uses halogen compounds and then UVB from sunlight which continue the sanitation and also destroy the halogens and possibly the combined halogens that form.. It would then seem to support what Ben said about outdoor pools. The bad stuff gets burned off by the sun (along with the good chlorine). To carry it one step further, if one is concerned about the health effects of chlorine in their pool then adding a UV unit could reduce the levels and also have a germicidal effect. Pretty much the claims made for UV units. Downside is the destruction of the necessary residual sanitizer.

    I found the wavelengths that were effective intersting....once again from my experiences with aquariums. UV units for aquariums usually peak about 280 angstroms... UVC/UVB light. I have used them and gave up on them. Never really saw any benifits. The article stated that most of the UV that came from through the atmosphere was in the 320 -400 range...UVA. Marine aquariums use a type of bulb known as an 'actinic' bulb which produces light in the 440 angstrom range but also produces a lot of light in the UVA range and many aquariums also use metal halide bulbs which produce a lot of UVB/UVA light. I have seen higher redox readings on aquariums with this type of lighting (used in reef tanks) than with standard lightling. However, algae thrives under this type of light but cyanobacteria do not. Don't really understand enough of what is going on chemically to explain it except that higher redox in an aqauarium promotes more green (good) algae and destroys red and bluegeen (bad) algae. Then again, the first type of algae that usually takes hold in a pool is green algae. I suspect this is connected to the redox potential of the water. As water quality deteriorates the redox potential lowers so green algae will appear when there is not enought FC to to kill it but there are still some oxidative processes going on (such as a pool with high CYA and 'normal' FC levels...sound familiar?). As these lessen the mustard and black algaes (related to the bluegeen algaes in tanks) take hold ( Usually when a pool has been neglected and there is no chlorine or the CYA levels have gotten sky high). Pure speculaton on my part...but food for thought!

    Sorry I can't relate more of this to pools but I have a lot more experience with aquariums and the effects of lighting (and we try and get rid of halogens in the water before we put the livestock in!) However, oxidation is an important process in an aquarium and redox is an important measurement. We use UV, ozone, and even hydrogen peroxide to treat the water to oxidize ammonia compounds and organics, then rely on nitrifying bacteria to convert what is left to nitrates, and finally, on anerobic denitrifying bacteria to convert the nitrates back into nitrogen gas so it can leave the water. If the organics cannot be sufficienly oxidized first then the nitrate levels get very high and denitrification is not sufficient to keep the nitrate levels down.

    One needs to understand that there is a difference between oxidation and disinfection. Oxidation occurs in an aquarium but many bacteria and algae thrive. This is why oxidation by itself is not adequite for a pool and, personally, makes me a bit suspect of relying on ORP controllers to determine proper sanitation levels. I am the first to admit that I don't know much about their application in pools firsthand but I do know that such chemicals as hydrogen peroxde, CYA, Oxone (MPS), and sodium percarbonate mess up ORP readings in pools (and test as TC on OTO and DPD tests). In fact, sodium percarbonate is no longer used as a non chlorine 'shock' for this very reason, since it was mainly used in commercial pools with ORP controllers (although it is sometimes pushed as a way to convert a biguinide pool to chlorine quickly).

    I realized that is seems that I have drifted off topic but I really haven't. Disinfection is necessary in a pool. Chlorine is the best disinfectant that we have. Many of the studies on pool disinfection are based on ORP readings of 650 mv or higher to determine proper sanitation levels but there seems to be a general fallacy in this since many factors can influance the ORP reading but don't really have an impact on actual sanitation and kill times. I personally would be more concerend about the health effects of low chlorine levels than I would about higher ones! As far as how much chlorine is safe....I don't think anyone really knows from what I have been able to research. It all seems rather arbitrary. Even the selection of 650 mv for ORP readings is an aribitrary selection. Florida requires an even higher reading (I believe it is 850 mv, gonna have to check the CPO text at work).
    Retired pool store and commercial pool maintenance guy.

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    Default Re: Safe swimming with elevated chlorine

    Evan
    I think one of the reasons for the green algae growth under these lighting conditions is the refraction and absorbance of light in a liquid (water) as well as the refraction in the cell membrane. Particulate matter with in the water may also effect the transition of light with in the body of water.


    As for chlorine’s health effects, I feel that inhalation is the greatest cause for concern (Pool doc has already coverd that one). The skin, being a selective membrane, can tolerate high levels of many materials depending on the transport material it is in. Our skin is selective in non isotonic solutions with exceptions that should not occur in a normal pool environment. I would have a greater concern if your pool is salted to an isotonic state.
    Solutions that could cause posing through the skin usually cause cell damage and prevent more absorbance through the body in general. The toxins that do manage to cross the epidermal layer are usually long term toxins causing general damage to the DNA.
    Before I get nailed I am speaking of the chemistry found in the normal residential pool setting.
    I would much rather deal with the few free radicals I may encounter in the pool with the right chlorine balance than deal with the microbe nastiness you will encounter with out it.
    Steve

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    Default Re: Safe swimming with elevated chlorine

    I just want you guys to know, I am watching this thread very closely, as I seem to be shocking (15-16ppm) more than not shocking these days due to the endless rain we've been having. Unless I get IN the pool to brush the sides it's not going to get done as I don't have the arm strength to brush the sides of our AGP from the outside.

    Keep the facts/best guesses coming. Fascinating.

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    Default Re: Safe swimming with elevated chlorine

    Quote Originally Posted by medvampire
    Evan
    I think one of the reasons for the green algae growth under these lighting conditions is the refraction and absorbance of light in a liquid (water) as well as the refraction in the cell membrane. Particulate matter with in the water may also effect the transition of light with in the body of water.
    Actually, the type of algae that grows in a marine aquarium is directly related to the redox potential of the water! This has been documented time and again with ORP meters. With lower ORP readings there is predominently red and blue green algae growth (cyanobacteria) and brown and green algae disappear. As the redox potential rises the red and blue green disappear and brown algae forms (I believe it is related to the Mustard algae in our pools) and finally, as the redox potential rises up to about 450mv the brown disappears and green algae is the predominent form seen.

    As for chlorine’s health effects, I feel that inhalation is the greatest cause for concern (Pool doc has already coverd that one).
    And this is primarily a concern of indoor pools.
    The skin, being a selective membrane, can tolerate high levels of many materials depending on the transport material it is in. Our skin is selective in non isotonic solutions with exceptions that should not occur in a normal pool environment. I would have a greater concern if your pool is salted to an isotonic state.
    Such as the salinity found in a salt water pool with about 3000 ppm NaCl? Interesting. I believe this is still below the isotonic point but not sure how much.
    Solutions that could cause posing through the skin usually cause cell damage and prevent more absorbance through the body in general. The toxins that do manage to cross the epidermal layer are usually long term toxins causing general damage to the DNA.
    Before I get nailed I am speaking of the chemistry found in the normal residential pool setting.
    I would much rather deal with the few free radicals I may encounter in the pool with the right chlorine balance than deal with the microbe nastiness you will encounter with out it.
    Steve
    On your last point I agree wholeheartedly 100%!
    Retired pool store and commercial pool maintenance guy.

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    Default Re: Safe swimming with elevated chlorine

    You all have me scared! I'm gonna hide under the bed...no, wait, there's dust and OTHER inhalable particles there....

    It's all about balancing and weighing risk. I prefer the risks of chlorine to the risks of water-borne diseases, viruses and other infections.
    Carl

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