This article seems thinly researched to me, and I am wondering why they don't link the cancer risk to chlorinated drinking water systems. I have tested water in my lab before and found the tap water from our sink was more highly chlorinated than the swimming pool water I was testing.

What are your thoughts on this article, and is APSP responding to this one? It seems to me this is very bad press for our indsutry and likely to be faulty science as well. Is the group doing this research an environmental group with an agenda? I find this very suspect. I'd be interested in knowing what everyone thinks about this article. It has been linked on the Drudge Report for several days.

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  • The Breitbart article linked to by Rex was posted on September 13th of this year. The study it refers to (and two companion studies) were posted on the Internet on September 12th herehere that includes links to the three related papers (same links I put in my first post to this thread).

    So your customers must have been referring to some earlier studies since they brought up concerns years ago, possibly something like this asthma study published in 2003 or this one from 2008 (I write about these studies in this thread. Or if it was specifically about cancer, then there is this study published online in 2006 linking chlorination disinfection by-products to an increase in bladder cancer. This last study (which is an epidemiological survey like the asthma studies, not an experiment like the ) basically showed a doubling of the risk of bladder cancer at 50 µg/liter THM levels with somewhat higher risk from showering, bathing and swimming than from drinking water (though the risk doubling is from total exposure, most of that being from showering). Sudies of commercial/public swimming pools often show 50-100 µg/liter THMs where outdoor residential swimming pool THMs would be expected to be far lower. In the U.S., there are around 70,000 new bladder cancer causes each year with around 15,000 deaths. Interestingly, the National Cancer Institute does not list chlorinated DBPs as associated with bladder cancer.
  • Did that and much more Mary. Wrote letters siting NSPF, Bio-Lab, NSF, etc. These folks were HOSTILE to chlorine and it was based on the article Rex sited at the beginning of this thread. The problem was likely one of credibility I think. After all, these were "researchers" and I'm a........."pool boy" in their mind. But like I said, after some years, they came around to our way and are now happy they did.
  • One thing you might be able to do, Bruce, to show them this is to test a sample of their tap water in front of them and show them it usually has chlorine in it. I have rinsed out test tubes and gotten a strong reading off the tap water many times testing water in the store.
  • I have experienced at least one customer that bought into these studies' conclusions and would not allow chlorine in any form to be used in their Texas pool. The argument they used was that chlorinated pool water is carcinogenic and could not be swayed. Somehow though, they did not mind drinking chlorinated tap water or showering in it. To them the pool was going to be dangerous. (Now mind you, this is a lawyer and Wall Street broker). They insisted on using an ionizer with built in ozone (or was it 02 injection, I was never sure of that machine). The pool was a difficult to impossible monster to maintain even with up to 8 ppm copper. After 5-6 yrs of struggle they sold themselves on my pre-construction recommendation and let me install SWG and ozone. The pool is now beautiful always.
    The bottom line is that yes, people do believe these articles, even the educated ones. Our message must get out there in a big way to counter the pseudo-science.
  • It seems to me that if anyone was really serious about determining the hazardous effects of chlorine, they would study pool service techs. No one is exposed to greater amounts of chlorine in all its forms, both by means of skin contact and inhalation, all day every day. I serviced pools for 16 years & have been away from it for 6 years now. The smell of chlorine coming off a pool guy's truck overwhelms me, where as before I never even noticed it. Based on this study we should all start dropping like flies pretty soon. That said, based on my experience & customer concerns, I am always looking for ways to reduce my customer's exposure to chlorine & its by products.
  • It was reported many places. Breitbart's site was a link to another location for the actual article I referenced, not written by the Breitbart site.
  • Unfortunately, the report wasn't just published by Breitbart, but by many other news organizations such as UPI that twisted the report into saying "swimming in chlorinated indoor pools can cause DNA damage" and "cause permanent DNA mutations" when in fact the actual report said "swimming was not associated with DNA damage detectable by the comet assay" which means that unrepaired DNA mutations were NOT found in human samples. In fact the data showed that there was a DECREASE in actual measured DNA damage from 1.5 +/- 0.7 to 1.3 +/- 0.6 (p=0.008 which means this is statistically significant with only an 0.8% chance of being a random variation). The micronucleated (MN) cell tests also showed that there was not significant damage that was repaired -- i.e. there wasn't significant damage period. It is only the mutagenicity tests of urine that showed a large increase (twice as mutagenic, on average) though even this had a 26% chance that this was just a random variation. In other words, in my opinion, the body was properly flushing out the THMs that were inhaled and got into the blood stream. There is only the implication that the increased mutation rate using standard bacterial tests on urine means there is greater potential for more DNA damage in the long-term.

    One should look at Table 2 in the study since it sums up what was observed overall. When looking at mean values of biomarkers for the four tests that were done, the only statistically significant result was a DECREASE in actual measured DNA damage in the comet assay. That is, the swimming overall on average doesn't point to any significant conclusion with regard to DNA damage, micronucleation or mutagenicity. The other study conclusions that were statistically significant have to do with correlations of changes with measured exposure levels of THMs in breath as shown in Table 3. This is where there was no significant correlation with any of the THMs for actual DNA damage so the statistically significant decrease (from 1.5 +/- 0.7 to 1.3 +/- 0.6) that was seen may have been due to the exercise itself (I'm speculating here). There was no statistically significant correlation with THMs and the micronucleated urothelial cells test. For the micronucleated lymhpocyte test, there was correlation only with the brominated THMs though on average the increase that was seen was from 3.4 +/- 2.4 to 4.0 +/- 2.8. For the urine mutagenicity test, only bromoform showed a statistically significant correlation (remember that this test showed the average doubling).

    As for how the people were using the pool, this was a controlled study so 49 non-smoking adult volunteers aged 18 to 50 who were asked to swim for 40 minutes in the indoor chlorinated pool. They were requested not to swim for one week prior to the experiment. There was a lot of variation in the actual distance swam during those 40 minutes from 0.05 to 1.75 kilometers (average 0.90 +/- 0.4 standard deviation). They did micronuclei and DNA damage tests on blood lymphocytes taken before and 1 hour after swimming. They did micronuclei tests of exfoliated urothelial cells before and 2 weeks after swimming. They did urine mutagenicity tests before and 2 hours after swimming.

    In the study, they note that "Physical activity has been shown in some studies (Schiffl et al. 1997) to be associated with genotoxicity through an effect on oxidative stress, but the results are not consistent (Battershill et al. 2008; Stephanie et al. 2008). In our study population, adjustment in the analysis for the intensity of physical activity during swimming did not confound effect estimates for exposures to DBPs." I still wish that they had used a control pool with low bather load and minimal DBPs.
  • Imagine; Breitbart sensationalizing a report! Perhaps he assumes that the swimming pool industry is predominantly inhabited by some of them liberal types.
  • Interesting observations. Another thing I wonder about in reading your comments, Richard, is HOW was the pool being used by the people they tested? Were they testing a swim team doing a vigorous workout, or an old lady like me who gets into the pool and relaxes, floats around, does some leg kicks and swims up and down a few times? People don't all get in their pools and swim vigorous laps. Some lounge around, some play with kids, some swim vigorously for excercise, some just jump in and cool off after doing yard work, etc. I would think these variations would need to be taken into into account and not just the chemical method of treating the pool. I am not a scientist, by any means, but reading this it seems to me whoever was doing the research had an agenda looking for some reason to find a conclusion linking chlorine to cancer, and of course the news media, who probably lives in an apartment in New York city and never even looks at a swimming pool sensationalizes this stuff.
  • The more I've looked into the detail of these three related studies, the more problems I find with them. One significant issue is that they had no control pools to compare against, such as ones with very low bather load so therefore much lower amounts of disinfection by-products. The reason this would be important would be to isolate results related to exercising (i.e. swimming) vs. the disinfection by-products themselves. If they could have a control with a pool not using chlorine or bromine, then that would have been even better to eliminate such products completely.

    For example, in their genotoxic study, they note that "swimming was not associated with DNA damage detectable by the comet assay." So far, so good, though this would not catch DNA damage that was subsequently repaired. They also note that "no significant associations with changes in micronucleated urothelial cells were observed." Also good, since that is a biomarker of DNA repair. However, they note that "the change in the frequency of micronucleated lymphocytes after swimming increased in association with exhaled concentrations of the brominated trihalomethanes (p=0.03 for CHCl2Br, p=0.05 for CHClBr2, p=0.01 for CHBr3) but not for chloroform" and that "urine mutagenecity increased significantly after swimming in association with the concentration of exhaled CHBr3 (p = 0.004)." Gee, that doesn't sound good, but wait...

    If we look at urine mutagenecity, it went from 0.6 +/- 2.3 to 1.2 +/- 2.2 Rev/ml-eq where the fraction of variance explained by exposure to THMs was only statistically significant with bromoform and even then that fraction was only 16% -- that is, most of the increase might be due to exercise itself (or from some substance not measured). If we look at the micronucleated lymphocytes, they increased only from 3.4 +/-2.4 to 4.0 +/- 2.8. In their text, they consider the micronucleated cell increases to be have increased non-significantly so I don't know why they bothered to refer to the non-significant increase that they associated with the brominated trihalomethanes in their "RESULTS" section.

    So the only really significant finding here was the factor of 7 increase in trihalomethanes (THMs) in the breath after swimming since it can be reasonably assumed that this did not come from exercise alone. However, the net result of this increase in terms of affects on the body that they looked at were only partially attributable to that increase in THMs (specifically to bromoform and to a lesser extent the other brominated THMs) and could instead be mostly attributable to exercise itself, possibly due to increased metabolic rates since increased metabolism and breathing results in greater intake of oxygen and associated free radical formation which can increase the rates of mutations.

    In practice, exercise is healthy in many ways, but it is "accelerated living" which may result in increased DNA damage which is mostly repaired. That is, it's a part of life and the benefits of exercise (such as improved cardiovascular health) outweigh the downside risk (such as DNA damage that is not repaired and on rare occasions could be cancerous). The opposite of this effect is the long life extension found by putting rats and other animals on significantly calorie-restricted diets. Slower metabolism means slower mutation rates and aging in general (telomere shortening, etc.), but a pretty sluggish life.
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