Chlorine Byproducts Linked to Higher Cancer Risk

A recent study from Sweden suggests that a common method of disinfecting drinking water may pose serious health risks. Researchers found that chemical byproducts formed during chlorination could increase the risk of bladder cancer by 33% and colorectal cancer by 15%.

The Role of Trihalomethanes in Public Water Systems

The study, published in Environmental Health Perspectives, identifies trihalomethanes (THMs) as the primary concern. THMs consist of four compounds—chloroform, bromodichloromethane, dibromochloromethane, and bromoform. These byproducts are present in nearly all public water systems in the United States and the European Union.

Lead researcher Emilie Helte of Sweden’s Karolinska Institute described the findings as “alarming” and called for further high-quality studies.

Chlorination: A Longstanding Practice With Unintended Risks

The United States has used chlorine to disinfect drinking water for over a century. The first city to implement chlorination was Jersey City, New Jersey, in 1908. This method successfully eliminated deadly waterborne diseases such as cholera and typhoid fever, leading to widespread adoption.

However, by the 1970s, scientists discovered that chlorine disinfection also produces harmful byproducts. Along with THMs, haloacetic acids (HAAs) are another group of potentially hazardous compounds. Both have been linked to increased cancer risks and reproductive health concerns.

The Environmental Working Group (EWG), a nonprofit research organization, has long warned of the dangers associated with THMs and HAAs. The group argues that current regulations fail to provide adequate protection.

Cancer Risk Findings From Large-Scale Review

The Swedish study reviewed 30 scientific studies involving over 90,000 participants. Researchers found that cancer risks rose significantly even at THM levels as low as 40 parts per billion (ppb).

For comparison, New York City’s drinking water contained THMs at an average of 38.1 ppb between 2013 and 2019, according to EWG data. The U.S. Environmental Protection Agency (EPA) currently allows a maximum of 80 ppb, while the EWG recommends a far stricter limit of just 0.15 ppb.

The research also suggests that men may face a higher cancer risk from THM exposure than women. However, the reasons behind this gender difference remain unclear.

Balancing Water Safety and Public Health

Although THM exposure poses risks, Helte emphasizes that reducing disinfectants in drinking water is not a simple solution. “It’s really important not to use too little disinfectant,” she explains, as inadequate water treatment could allow dangerous pathogens to spread.

Replacing chlorine with alternative disinfection methods or installing advanced filtration systems would require significant infrastructure investments. Until then, Helte advises people to continue drinking tap water but suggests using granular activated carbon filters to reduce chemical exposure at home.

Broader Concerns Over Water Contaminants

The study on THMs comes amid growing concerns over contaminants in U.S. drinking water. Other research has highlighted the presence of per- and polyfluoroalkyl substances (PFAS), commonly referred to as “forever chemicals.” These synthetic compounds have been linked to various health issues, including a 33% higher incidence of certain cancers.

As more evidence emerges about potential health risks from drinking water contaminants, scientists and policymakers face increasing pressure to reevaluate current water treatment practices and safety standards.

Reducing Exposure With Advanced Filtration

For those concerned about THMs and other contaminants, reverse osmosis filtration offers an effective solution. Reverse osmosis systems remove THMs, HAAs, PFAS, and other harmful chemicals by forcing water through a semi-permeable membrane. Whole-home water conditioners can further enhance water quality by addressing additional impurities.

While municipal water treatment remains essential for public health, individuals can take steps to minimize exposure to potentially harmful byproducts through home filtration solutions.

Source: NYPost