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.
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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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Re: Safe swimming with elevated chlorine
Originally Posted by PoolDoc
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