Research on Chlorine and cancer????

[duganderson]

I've seen some information about potential links between chlorine in pools/hot tubs and cancer. What are the thoughts of folks about the potential risk of cancer and chlorine?

Is this only something to be concerned about at super high chlorine levels?

Is the risk in hot tubs worse (compared to pools) due to the hot water?

Do you think there is a safety benefits in trying maintain lower chlorine levels in the tub 1-2 FC and then supplement with chlorine after use? Currently I keep mine in the 1-3 FC range and add chlorine after soaks.

Thanks for your thoughts! Doug

 

[jseyfert3]

My very limited understanding is that it has nothing to do with the FC level, but some CCs are indeed known carcinogens. The use of chlorine as a sanitizer is still very much supported though, because a slight increase in risk of cancer is very much outweighed by the reduction or elimination of other, very well known harmful things that grow in unsanitized water.

The risk would likely be higher in hot tubs not due to temp but due to the often higher levels of CCs due to high bather loads in a small amount of water and the large amounts of aeration driving those off during use of the tub.

One thing that could be useful would be running the jets with air valves open for a bit before getting in the tub, to help drive off any of the more easily driven off CCs. Other than that properly maintaining the FC in tub at all times will help reduce the total amount of CCs produced.

Like anything in life ultimately it’s risk management. You usually can never eliminate all risk, but some risks are much better than other risks.

 

[Leebo]

I've seen some information about potential links between chlorine in pools/hot tubs and cancer. What are the thoughts of folks about the potential risk of cancer and chlorine?

Is this only something to be concerned about at super high chlorine levels?

Before we dive into the discussion, can we too read the articles or information you’re asking about?

 

[PoolGate]

I'd love to read the articles. Off the cuff I'm wondering if the people that sell ozone systems did the research.

 

[JoyfulNoise]

So this is situation where one must be very careful in understanding the study of carcinogens and the epidemiology of cancer. Making rash generalization and using “scary words” like “cancer” doesn’t help at all.

Cancer causing chemicals almost always follow a dose-response, or exposure-response, relationship. In other words, just because a chemical substance CAN cause cancer does not imply that it will cause cancer. Typically one needs to be exposed to a chemical at a sufficient concentration for a long enough time period to be at risk. So just saying that some chemical related to a hot tub causes cancer doesn’t really tell you much of anything at all. Remember, you can die if you drink too much water all at once.

As others have stated, chlorine is not considered a carcinogen. It is the organic compounds that chlorine reacts with that, in some circumstances, can increase one’s risk of cancer. Again, it depends a lot on what exactly we are talking about.

 

[wireform]

I happened to be in a small take out some years back and they were taking lessons on how to keep cutting boards, knives and the like sanitary without ever leaving a trace that will make people sick. I was intrigued to say the least and love to learn..... the guy took straight beach not alot and mixed it with water but it still had the bleach smell. Soaked a rag and continued to demonstrate how to wipe down surfaces and utensils that are used for prepping which sit on the prepping counters. He them looked at me and said if I can drink this then you have nothing to worry about. He then mixed a tiny amount with water in a cup and took a good sip. He said it'll do what in needs to do to sanitize without hurting you, obviously the mix in the cup wasn't nearly as strong as the other stuff was but he was just demonstrating what needs to be done to be safe and not make people sick.

 

[Mdragger88]

I for one am not too concerned- my tap water that i drink has higher active levels of chlorine than my hot tub. I am however concerned with person to person transmission of pathogens that can occur quickly in under sanitized bodies of water. As well as things like legionella pneumonia & Pseudomonasfolliculitis (hot tub rash).

 

[RDspaguy]

one needs to be exposed to a chemical at a sufficient concentration for a long enough time period to be at risk.

Oh Crud. I'm SCREWED!

 

[JoyfulNoise]

Oh Crud. I'm SCREWED!

I’d be more worried about all that nasty spray foam insulation they use inside the cabinet … have you ever read the labels on that stuff ?!?!

 

[duganderson]

Here's the article that I had initially read.....

Chlorinated Pools May Increase Cancer Risk

Swimming in a chlorinated pool may increase your risk of developing cancer, suggest a new suite of studies, which identified more than 100 chemical byproducts in pools that use chlorine as a disinfectant.

www.nbcnews.com

.....I absolutely agree that there is risk in everything and common sense is important. I was not trying to freak people out about the use of chlorine because I'm guessing that an unsanitary hot tub is WAY more dangerous.

I was just try to get a sense from folks if they think it may be helpful or increase safety to consider tying to keep chlorine levels low (like 1-2 PPM) during the soak AND adding chlorine after the soak to account for the bather chlorine demand created.

 

[Leebo]

Thank you greatly for sharing the story! The first thing that jumps out to me is the year it was published, over ten years ago. This lead me to read the published article which has this as a closing conclusion,

Conclusions​

We detected a slight increase in serum CC16, a marker of lung epithelium permeability, in healthy adults after they swam in an indoor chlorinated pool. Exercise and DBP exposure explained this association, without involving inflammatory mechanisms. Further research is needed to confirm the results, establish the clinical relevance of short-term serum CC16 changes, and evaluate the long-term health impacts.

I’d be interested next in seeing if further research was ever funded/done.

 

[JoyfulNoise]

My emphasis added -

….in healthy adults after they swam in an indoor chlorinated pool …

An indoor chlorinated pool has radically different air quality factors than an open air hot tub. The two situations are not even remotely comparable. Aside from air quality factors there are also widely varying degrees of pool water quality and maintenance.

Low chlorine is really not an issue. TFP stresses the dichlor-then-bleach method because it is imperative to have a minimum of 30ppm CYA in a chlorinated hot tub. Why? Because the presence of CYA modifies the rates of reaction of chlorine with different organic compounds and reduces the likelihood of forming some of the nastier THM and DBP compounds. For example, when there is no CYA in water and chlorine is allowed to react with nitrogen compounds, the far more dangerous nitrogen trichloride CC will be favored (it will have the faster reaction kinetics). When CYA is present, monochloramine is much more likely to form and it is far less reactive and dangerous than nitrogen trichloride. So again, circumstances matter A LOT when we talk about chlorine as a source of potentially harmful chemical reactions.

 

[Leebo]

Risks and Benefits of Pool Chlorination, with Manolis Kogevinas | The Researcher's Perspective | 1 November 2010

Chlorine is one of the most common disinfectants used to kill microbes in water and make it safe for humans to swim in and drink. But when chlorine and other disinfectants combine with organic matter in pools such as sweat, urine, and skin cells, the results are disinfection by-products (DBPs)...

ehp.niehs.nih.gov

Here’s an interesting interview with the doctor who talks about the paper. Make your own call, but to me the NBC article seemed to contain a bit of “doom” compared to this discussion.

 

[duganderson]

TFP stresses the dichlor-then-bleach method because it is imperative to have a minimum of 30ppm CYA in a chlorinated hot tub. Why? Because the presence of CYA modifies the rates of reaction of chlorine with different organic compounds and reduces the likelihood of forming some of the nastier THM and DBP compounds. For example, when there is no CYA in water and chlorine is allowed to react with nitrogen compounds, the far more dangerous nitrogen trichloride CC will be favored (it will have the faster reaction kinetics). When CYA is present, monochloramine is much more likely to form and it is far less reactive and dangerous than nitrogen trichloride.

JoyfulNoise....thank you for sharing this. Very interesting!!!! I know that 30 PPM is recommended but the rationale I have generally heard is that the CYA reduces the harshness of chorine on swimsuits, eyes, skin, etc. I did not realize that CYA increases the safety in this manner too!! I learn something new on this forum all of the time.....Thanks for your contribution.

 

[duganderson]

Risks and Benefits of Pool Chlorination, with Manolis Kogevinas | The Researcher's Perspective | 1 November 2010

Chlorine is one of the most common disinfectants used to kill microbes in water and make it safe for humans to swim in and drink. But when chlorine and other disinfectants combine with organic matter in pools such as sweat, urine, and skin cells, the results are disinfection by-products (DBPs)...

ehp.niehs.nih.gov

Here’s an interesting interview with the doctor who talks about the paper. Make your own call, but to me the NBC article seemed to contain a bit of “doom” compared to this discussion.

Interesting interview. Thanks for sharing!

 

[5tan]

dbp pool - Search Results - PubMed

dbp pool - Search Results - PubMed

pubmed.ncbi.nlm.nih.gov

DBPs are the industry term for "disinfection byproducts". Search PubMed for publications relating to DBPs in pools. All kinds of reading material, filter by most recent 5 year, then check references to older publications that may be of interest. Typically newer publications build upon the research of older publications.

If you have academic research credentials, you may find the full-text of this research interesting: "Production of various disinfection byproducts in indoor swimming pool waters treated with different disinfection methods"

 

[JoyfulNoise]

Conclusion from this study -

The mutagenicity of these pool waters was similar to that of drinking water, indicating that the levels of mutagenic DBPs are similar in both waters.

So, in other words, don’t drink indoor pool water and you’ll be fine

 

[Mdragger88]

Conclusion from this study -



So, in other words, don’t drink indoor pool water and you’ll be fine

That makes it sound like I shouldn’t be drinking “drinking water” maybe not…

 

[JoyfulNoise]

That makes it sound like I shouldn’t be drinking “drinking water” maybe not…

The “mutagenicity” referred to in that study was mutations in the sequenced DNA of know strains of bacteria. Hardly a direct comparison to humans.

If you’re worried, install an RO filter tap by your sink and only drink from that.

 

[Mdragger88]

The “mutagenicity” referred to in that study was mutations in the sequenced DNA of know strains of bacteria. Hardly a direct comparison to humans.

If you’re worried, install an RO filter tap by your sink and only drink from that.

Lol - I’m not worried
been drinking tap water for almost 40 years, it’s a little late in the game to worry about it now. & So far my kids both seem normal ….