Daniel Hoffmann 🌼
#Chlorination of drinking water is statistically associated with #cancer (bladder, colorectal). On the other hand it has reduced waterborne infections. Fortunately, there are ways out of this dilemma. https://www.theguardian.com/us-news/2025/feb/17/water-chlorination-cancer-risk-us-eu
Water chlorination levels in US and EU likely increase cancer risk, study finds

Bladder cancer risk increased 33% and colorectal cancer by 15% in using chlorine to disinfect water

The Guardian
Feb 17, 2025 at 3:47pmWeb
Show threadLee CFeb 20, 2025
@Daniel_Hoffmann Thanks for boosting this @TalktoBeverley
Oddly I was only wondering a few days ago, whether there could be a link between my chlorine sensitivity and other illnesses. I can't go anywhere near a chlorinated swimming pool anymore. I do wonder whether drinking water chlorination might cause other conditions too.
Show threadBeverleyFeb 20, 2025

@LJClements8

Oh, I do hope it helps solve a few issues for you Lee, though obviously I'm sorry you have these conditions.

I can't quite recall how I came across @Daniel_Hoffmann but definitely worth a 'follow'. I think someone else I follow boosted something of his...

Wishing you well.

Show threadLee CFeb 21, 2025
@TalktoBeverley @Daniel_Hoffmann Getting the NHS to take things like this seriously is always a challenge. If it doesn't give you anaphylactic shock, they rarely want to investigate further. I don't get the distinction they make between allergies and sensitivities, both cause unpleasant symptoms/reactions that can often be quite disabling.
Show threadBeverleyFeb 21, 2025

@LJClements8 @Daniel_Hoffmann

I need to look into this. I'd never considered the difference between allergies and sensitivities.

A family member has a range of peculiar symptoms and I can't get anyone to take their situation seriously. I've suggested dysautonomia to our GP but beyond wearing a heart monitor for a day and finding nothing, that's been the end of it.

I'm banging my head against a brick wall. They're not exactly in immediate danger, but their life is miserable at times.

Show threadDaniel Hoffmann 🌼Feb 21, 2025
@TalktoBeverley @LJClements8 @Daniel_Hoffmann Dysautonomia sounds like something for a neurologist.
Show threadBeverleyFeb 21, 2025

@Daniel_Hoffmann @LJClements8

Yes indeed, and since I got nowhere with our GP, I've sent several e-mails to professionals listed on the following website, which have been ignored.

http://www.dysautonomiainternational.org/page.php?ID=14

I'm at my wits end.

Dysautonomia International:

How to Find a Doctor With Experience in Autonomic Disorders You can use the regional listing below, or the Interactive Global Dysautonomia Map to find a physician. Please note that this is not a comprehensive list of all doctors capable of treating patients with autonomic disorders, and some of the doctors on this list may be better qualified than others to treat certain conditions. Adding a Physician to the List If you are a physician who treats one or more forms of dysautonomia and you would like to be included on this list, please send your bio or c.v. to us at [email protected]. Please be sure to indicate your full name, address, phone, specialty, and form(s) of dysautonomia treated. We will be in touch with you after receiving the e-mail. If you are a patient and you would like to recommend a physician for inclusion on our list, please ask the physician to e-mail us. We ask that they do this because we really want to be sure that the physicians on our list are qualified and also interested in treating patients with dysautonomia.

Show threadDaniel Hoffmann 🌼Feb 21, 2025
@TalktoBeverley @LJClements8 @Daniel_Hoffmann An allergy is always an immune (over-)reaction. Sensitivity is broader and can but doesn't need to involve immune responses. For instance, if I had a defect in a gene for an enzyme that removes a product of a normal biochemical reaction, that product will accumulate and eventually become a problem. In that case I would be sensitive to that product.
Show threadBeverleyFeb 21, 2025

@Daniel_Hoffmann @LJClements8

Daniel, thank you for taking the time to explain. I appreciate the interaction.

In relation to my family member, they have so many symptoms it's really difficult to disentangle them. Web searches can be helpful, but often create more questions than answers, especially for a lay person.

Show threadLee CFeb 22, 2025
@Daniel_Hoffmann @TalktoBeverley Thanks for explaining that, that's really helpful. It's been so difficult to get answers, explanations or even any interest from medical professionals, even though continually having reactions to everything from food to fragrances to medication does (as Beverley commented) make life pretty miserable at times.
Show threadLee CFeb 22, 2025
@TalktoBeverley @Daniel_Hoffmann There is something I've come across called Mast Cell Activation Syndrome (MCAS), which corresponds with many of my symptoms, but again it's something there's sadly little interest in among UK medical professionals. Just another brick wall.
Show threadDaniel Hoffmann 🌼Feb 22, 2025
@LJClements8 @TalktoBeverley @Daniel_Hoffmann Try to find an allergologist. They should be able to test for MCAS or related conditions.
Show threadBeverleyFeb 21, 2025

@LJClements8

So because of my family member, I understand your difficulties to some extent... I'm so sorry.

Show threadDaniel Hoffmann 🌼Feb 20, 2025

@LJClements8 @Daniel_Hoffmann @TalktoBeverley Chlorine is an effective disinfectant because it kills germs (actually our own immune system can produce small amounts of it as defense against bacteria). In high concentrations it most certainly will damage our own cells, and it has been used repeatedly as a deadly chemical weapon (check out the Wikipedia page on chlorine). Such concentrations will not be reached under normal circumstances at a swimming pool. But I agree that the smell can be repellent.

The story with chlorine in drinking water is different. People drink a lot of water for a long time. So we have long-term exposure to low concentrations of a by-product (trihalomethane) of disinfection with chlorine. The article in the Guardian references a study that shows that these by-products increase risks for certain cancers.
https://ehp.niehs.nih.gov/doi/10.1289/EHP14505?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed

Show threadLee CFeb 21, 2025
@Daniel_Hoffmann @TalktoBeverley
Could the chlorine in low doses not kill gut bacteria though?
It's not just the smell. Swimming pool water gives me a whole raft of (respiratory) allergy symptoms.
Show threadDaniel Hoffmann 🌼Feb 21, 2025
@LJClements8 @Daniel_Hoffmann @TalktoBeverley There are studies that show a difference in gut microbiomes (see below), though it seems not catastrophic esp. in comparison to the benefits (less diarrhea in children). What that means long-term is difficult to say. We know that there is an increased risk of colorectal cancer, but it's unclear (to me) whether that's mediated by the changes in the microbiome.
Your strong response to chlorinated pool water: could be that you are more sensitive or that people there use higher chlorine doses.
https://www.nature.com/articles/s41564-022-01101-3
Drinking water chlorination has minor effects on the intestinal flora and resistomes of Bangladeshi children - Nature Microbiology

A substudy nested within a double-blind cluster-randomized controlled trial in Bangladesh shows that drinking chlorinated water had relatively minor impacts on children’s gut microbiome development in this setting.

Nature