Chloramination May Introduce Cancer-Causing Chemicals

Methadone, a pain medication often used to help addicts abstain from heroin and other opiates, appears to be seeping into the water supply in ways that could be dangerous, according to new research.

A study published in May in the journal Environmental Science & Technology Letters linked methadone to the chemical N-Nitrosodimethylamine (NDMA), which the World Health Organization labels as “clearly carcinogenic.” NDMA is a disinfection byproduct found in water.

Scientists have traced some of the origins of NDMA in water. “Several specific precursor chemicals present during chloramination are known but cannot account for the total observed NDMA formation potential in drinking waters,” the study said.

Herbicide used on farms and over-the-counter drugs such as antihistamines are known to produce NDMA during the chloramination process. “But the environmental levels of these chemicals in most places are too low to account for the abundance of NDMA found in wastewater supplies,” PBS Newshour reported.

The study found that methadone is a potential precursor chemical for NDMA. That’s because methadone contains a dimethylisopropylamine functional group, which reacts during chloramination to form NDMA, according to the research.

Why the study is groundbreaking: “This work is among the first to contrast known public health benefits of pharmaceutical-taking patients against the potential exposure of millions of people to physiologically relevant levels of carcinogenic NDMA in chloraminated drinking water,” the study said.

The researchers used a device known as a QTOF mass spectrometer during the study. “After scanning 800 likely compounds, the search landed on methadone. They found that methadone likely accounted for up to 62 percent of the NDMA in the wastewater samples,” PBS reported.

They also tested 10 drinking water samples from the U.S. and Canada. “Half of the drinking water samples carried detectable amounts of methadone — in the range of tens to hundreds of nanograms. This methadone content would be too low to get a person high, but more than enough to spawn a risky level of NDMA, the researchers found. They calculated that the consequent levels of NDMA would be enough to be banned in places like Canada, Massachusetts and California, where the carcinogen is regulated,” PBS reported.

Environmental scientist Susan Richardson of the University of South Carolina, who was not part of the study, explained why this research matters.

“It’s a very important paper, as NDMA is a very potent carcinogen,” she said, per PBS. “It’s being commonly found in drinking water well above the health reference level for cancer, and the U.S. Environmental Protection Agency is currently deciding whether to regulate it.”