Is bladder cancer risk associated with exposure to trihalomethanes (THMs) through ingestion of water, and through inhalation and dermal absorption during showering, bathing, and swimming in pools?
Shower Dechlorination Filter, a case-control study (Am J Epidemiol 2006, PMID 17079692) — the odds ratio for duration of shower or bath weighted by residential THM level was 1.83 for the highest compared with the lowest quartile. The abstract for Shower Dechlorination Filter states no limitations.
Source: Am J Epidemiol 2006, PMID 17079692 ↗ · Research map · How Magellan grades evidence · evidence confidence: medium
Am J Epidemiol · 2006 · PMID 17079692 · DOI 10.1093/aje/kwj364
Long-term exposure to trihalomethanes (THMs) from chlorinated water, through drinking, showering/bathing, and swimming, is associated with an increased risk of bladder cancer.
The question
Is bladder cancer risk associated with exposure to trihalomethanes (THMs) through ingestion of water, and through inhalation and dermal absorption during showering, bathing, and swimming in pools?
What they tested
The authors hypothesized that bladder cancer risk would be associated with exposure to THMs through various routes, including ingestion, inhalation, and dermal absorption.
How they did it
A case-control study was conducted in Spain between 1998 and 2001, involving 1,219 bladder cancer cases and 1,271 controls. Lifetime personal information on water consumption and water-related habits was collected and linked with THM levels in geographic study areas.
What they found
Long-term THM exposure was associated with a twofold bladder cancer risk, with an odds ratio of 2.10 for average household THM levels of >49 versus <=8 micro g/liter. Ingestion exposure of >35 micro g/day had an odds ratio of 1.35 compared to not drinking chlorinated water. The odds ratio for duration of shower or bath weighted by residential THM level was 1.83 for the highest compared with the lowest quartile. Swimming in pools was associated with an odds ratio of 1.57.
| Household THM levels (>49 vs <=8 micro g/liter) | 2.1 | |
|---|---|---|
| Ingestion THM exposure (>35 micro g/day) | 1.35 | |
| Highest quartile shower/bath duration weighted by THM | 1.83 | |
| Swimming in pools | 1.57 |
Odds ratios for bladder cancer risk associated with different types and levels of THM exposure.
What it means
Bladder cancer risk was associated with long-term exposure to THMs in chlorinated water at levels commonly found in industrialized countries.
Limitations
The abstract does not explicitly state any limitations of the study.
Where the published abstract does not list limitations, we say so rather than inventing them. Read the full paper on PubMed before drawing conclusions.
The paper at a glance
| Title | Bladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools. |
|---|---|
| Journal | Am J Epidemiol |
| Year | 2006 |
| PMID | 17079692 ↗ |
| DOI | 10.1093/aje/kwj364 ↗ |
| Topic | Immunity, inflammation & resilience |
Read the source: PubMed record (authors, abstract, full citation) ↗ · Publisher via doi.org ↗
Where Magellan uses this paper
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Shower Dechlorination Filter
The compounds this filter targets - trihalomethanes and related disinfection by-products - have been most consistently linked in human epidemiology to bladder cancer, with meta-analyses reporting roughly 30-60% higher risk among the most exposed and more recent work also suggesting a modest colorectal-cancer…
A shower dechlorination filter is a point-of-use device that reduces free chlorine and chlorine-derived…
Research describes the compound or intervention studied. It is not a claim about any specific product.
Cite this page
These citations point at this summary. To cite the original paper with its full author list, use the PubMed record or doi.org.
Magellan Longevity. (2026). Is bladder cancer risk associated with exposure to trihalomethanes (THMs) through ingestion of water, and through inhalation and dermal absorption during showering, bathing, and swimming in pools? [Plain-English summary of Am J Epidemiol 2006, PMID 17079692, DOI 10.1093/aje/kwj364]. Magellan Longevity. https://magellanlongevity.com/study/s190.html@misc{magellan_s190,
title = {Is bladder cancer risk associated with exposure to trihalomethanes (THMs) through ingestion of water, and through inhalation and dermal absorption during showering, bathing, and swimming in pools?},
author = {{Magellan Longevity}},
year = {2026},
howpublished = {\url{https://magellanlongevity.com/study/s190.html}},
note = {Plain-English summary of PubMed PMID 17079692; DOI 10.1093/aje/kwj364; Am J Epidemiol 2006. Reviewed by Gabriel Radu, DO},
urldate = {2026-08-11}
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