---
title: "Disinfection by-products in drinking water and risk of…"
description: "High levels of trihalomethanes in drinking water may increase the risk of proximal colon cancer in men."
url: "https://magellanlongevity.com/study/d37551954.md"
canonical: "https://magellanlongevity.com/study/d37551954.html"
html: "https://magellanlongevity.com/study/d37551954.html"
type: "study"
study_key: "d37551954"
journal: "J Natl Cancer Inst"
year: 2023
pmid: "37551954"
doi: "10.1093/jnci/djad145"
citations: 1
updated: 2026-09-02
author: "Gabriel Radu, DO"
author_credentials: "Physiatrist (PM&R). NY medical license 275110. NPI 1376861765."
publisher: "Magellan Longevity"
content_format: "markdown"
---

# Disinfection by-products in drinking water and risk of colorectal cancer: a population-based cohort study

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## Citation

| Field | Value |
| --- | --- |
| Journal | J Natl Cancer Inst |
| Year | 2023 |
| PMID | [37551954](https://pubmed.ncbi.nlm.nih.gov/37551954/) |
| DOI | [10.1093/jnci/djad145](https://doi.org/10.1093/jnci/djad145) |
| Study key | d37551954 |

## Takeaway

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?

## Hypothesis

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.

## Methods

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.

## Results

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.

## Conclusion

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.

## Verbatim from the abstract

> disinfection by-products in drinking water may be a possible risk factor for colon cancer

## Hazard Ratios for Colorectal Cancer by THM Exposure in Men

| Measure | Hazard Ratio |
| --- | --- |
| 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.*

## Where this study is used on Magellan

This paper is one of the citations behind the evidence grade on the pages below. Grades are assigned from the published research and are independent of affiliate commissions.

| Compound or device | Evidence grade | Graded pages |
| --- | --- | --- |
| Shower Dechlorination Filter | Emerging evidence | [Shower Dechlorination Filter](https://magellanlongevity.com/p/190.md) |

## Reference

1. **Disinfection by-products in drinking water and risk of colorectal cancer: a population-based cohort study**
   J Natl Cancer Inst 2023 · [PMID 37551954](https://pubmed.ncbi.nlm.nih.gov/37551954/) · [DOI 10.1093/jnci/djad145](https://doi.org/10.1093/jnci/djad145)

   > disinfection by-products in drinking water may be a possible risk factor for colon cancer

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## Scope and disclosures

Educational information, not medical advice. Nothing here is intended to diagnose, treat, cure, or prevent any disease. Talk to your physician before starting any supplement or device, especially if you are pregnant, nursing, or taking medication.

Editorial firewall: evidence grades are assigned from the published research and are independent of any affiliate commission. As an Amazon Associate, Magellan Longevity earns from qualifying purchases.

Reviewed for accuracy by a board-certified physician (DO).