Water, if anything, should have flavor, but not be dangerous. A Swedish study reveals that chemicals in drinking water may increase cancer risk. Chlorination byproducts in drinking water are linked to an increased bladder and colorectal cancer risk. What does the future hold where safe drinking water is concerned?
The Double-Edged Sword of Water Chlorination
Chlorination, a cornerstone of public health safety since 1908, has significantly reduced waterborne illnesses in the United States. However, recent research suggests that this practice may come with unintended consequences. A Swedish analysis reports that chlorine disinfection in water creates byproducts called trihalomethanes (THMs), which could increase bladder cancer risk by 33% and colorectal cancer risk by 15%.
THMs, consisting of chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are present in nearly all public water systems in the US and EU. This widespread presence has raised concerns among health experts and environmental groups about the long-term health implications of chlorination.
A new analysis out of Sweden reports that disinfecting water with chlorine creates chemical byproducts that can increase the risk of bladder cancer by 33% and colorectal cancer by 15%.
https://t.co/feo5i4Hi3d— Amber Lake Farm(stead) 🕊️ (@AmberLakeFarm) February 19, 2025
The Evolution of Water Treatment Concerns
By the 1970s, scientists had identified harmful byproducts from chlorination, including THMs and haloacetic acids (HAAs). The Environmental Working Group (EWG) has been at the forefront of warning about cancer and reproductive risks associated with these chlorination byproducts. Their concerns have been further validated by recent research.
“What we see is alarming and we need some more high-quality tudies.” – Emilie Helte
The study reviewed 30 scientific studies with over 90,000 participants, finding cancer risks at THM levels as low as 40 ppb. This is particularly concerning given that NYC’s water supply had THM levels of 38.1 ppb from 2013-19, according to EWG data. The US currently limits THM in drinking water to 80 ppb, while the EWG recommends not exceeding 0.15 ppb.
Chlorine in tap water, watch how fast it absorbs into your skin.
Chlorine is in 100% of all tap water in the world, and is also recognized carcinogen.
is known to irritate the eyes, soft tissues and mucous membranes of the nose and lungs and exacerbate allergies asthma symptom pic.twitter.com/aaOUkK1Xf9
— Chris (@chrisdrieg) February 16, 2025
Balancing Disinfection and Safety
While the risks associated with chlorination byproducts are concerning, experts caution against completely abandoning this crucial disinfection method. Emilie Helte, the study’s lead author, emphasizes the importance of maintaining adequate disinfection levels to prevent waterborne diseases.
As a preventative measure, Helte suggests using granular activated carbon filters at home to reduce harmful chemicals. This recommendation comes as the research aligns with recent reports on “forever chemicals” in US water linked to higher cancer incidences, highlighting the need for comprehensive water treatment solutions.
The Path Forward
The findings of this Swedish study underscore the need for further research and potential policy changes regarding water treatment practices. As scientists continue to investigate the long-term effects of chlorination byproducts, it becomes increasingly important for consumers to stay informed about their water quality and consider additional filtration methods at home.
While chlorination remains essential for preventing waterborne illnesses, the balance between disinfection and minimizing harmful byproducts presents a challenge for water treatment facilities and policymakers. As research progresses, it is likely that we will see evolving guidelines and treatment methods aimed at safeguarding public health while minimizing long-term risks associated with water disinfection byproducts.
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