Is there an association between long-term exposure to trihalomethanes (THMs) in drinking water and the incidence of colorectal cancer in humans?
Disinfection by-products, a cohort study in 58,672 men (J Natl Cancer Inst 2023, PMID 37551954) — over an average follow-up of 16.8 years (988,144 person-years), 1913 colorectal cancer cases were identified. Scope: 58,672 men, and the abstract states no limitations.
Source: J Natl Cancer Inst 2023, PMID 37551954 ↗ · Research map · How Magellan grades evidence · evidence confidence: medium
J Natl Cancer Inst · 2023 · PMID 37551954 · DOI 10.1093/jnci/djad145
High levels of trihalomethanes in drinking water may increase the risk of proximal colon cancer in men.
The question
Is there an association between long-term exposure to trihalomethanes (THMs) in drinking water and the incidence of colorectal cancer in humans?
What they tested
The study implicitly hypothesizes that long-term exposure to THMs, known rodent carcinogens, may be associated with an increased risk of colorectal cancer in humans, despite inconclusive prior evidence.
How they did it
This population-based cohort study assessed the association of long-term THM exposure with colorectal cancer incidence in 58,672 men and women from two cohorts. Exposure was determined by combining residential history with drinking water-monitoring data, categorizing participants into no exposure, low exposure (<15 µg/L), and high exposure (≥15 µg/L). Incident colorectal cancer cases were identified using the Swedish National Cancer Register.
What they found
Over an average follow-up of 16.8 years (988,144 person-years), 1913 colorectal cancer cases were identified. High THM concentrations (≥15 µg/L) were associated with an increased risk of colorectal cancer in men (hazard ratio = 1.26). This association was statistically significant for proximal colon cancer in men (hazard ratio = 1.59) but not for distal colon or rectal cancer. No overall association was observed in women.
| Colorectal Cancer (High Exposure) | 1.26 | |
|---|---|---|
| Proximal Colon Cancer (High Exposure) | 1.59 |
Hazard ratios for colorectal cancer and proximal colon cancer in men exposed to high THM concentrations (≥15 µg/L) compared to no exposure.
What it means
The results suggest that disinfection by-products, specifically THMs in drinking water, may be a possible risk factor for proximal colon cancer in men, even at concentrations lower than those in most previous studies.
Limitations
The abstract does not explicitly state limitations of the study, but it notes that evidence in humans for carcinogenicity associated with disinfection by-products is still inconclusive, implying the need for further research.
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 | Disinfection by-products in drinking water and risk of colorectal cancer: a population-based cohort study |
|---|---|
| Journal | J Natl Cancer Inst |
| Year | 2023 |
| PMID | 37551954 ↗ |
| DOI | 10.1093/jnci/djad145 ↗ |
| Topic | Environment, air, water & exposures |
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 there an association between long-term exposure to trihalomethanes (THMs) in drinking water and the incidence of colorectal cancer in humans? [Plain-English summary of J Natl Cancer Inst 2023, PMID 37551954, DOI 10.1093/jnci/djad145]. Magellan Longevity. https://magellanlongevity.com/study/d37551954.html@misc{magellan_d37551954,
title = {Is there an association between long-term exposure to trihalomethanes (THMs) in drinking water and the incidence of colorectal cancer in humans?},
author = {{Magellan Longevity}},
year = {2026},
howpublished = {\url{https://magellanlongevity.com/study/d37551954.html}},
note = {Plain-English summary of PubMed PMID 37551954; DOI 10.1093/jnci/djad145; J Natl Cancer Inst 2023. Reviewed by Gabriel Radu, DO},
urldate = {2026-08-11}
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