Acesulfame K passes through the human body into wastewater, survives water treatment and accumulates in groundwater, Swiss researchers have found.

Acesulfame K turned out to be much more resilient towards treatment than saccharin, sucralose, and cyclamate – three other popular and commonly used artificial sweeteners.

The scientists tested tap water, urban groundwater, and both treated and untreated water samples from 10 different wastewater treatment plants. They also collected water samples from four rivers and eight lakes near Zurich and from a remote alpine lake.

In the untreated wastewaters, they could detect the presence of all four sweeteners (acesulfame K, saccharin, sucralose, and cyclamate), but in treated water 90% of saccharine and 99% of cyclamate were eliminated. Sucralose withstood treatment somewhat better, but the concentrations were still small. Surprisingly enough, acesulfame K proved much more resilient towards treatment and the equivalent of 10 milligrams per person per day could be detected in both untreated and treated waters.

Treated water often end up in lakes and rivers and no one knows whether acesulfame K has any impact on fish or the environment.

“These concentrations are astronomically high,” says Associate Professor Bruce Brownawell, an environmental chemist at Stony Brook University, New York “If I had to guess, this is the highest concentration of a compound that goes through sewage treatment plants without being degraded.”

The research team found no detectable amounts of artificial sweeteners in the remote alpine lake, but in the other rivers and lakes the amount of acesulfame K increase proportionally with nearby human population sizes. Acesulfame could also be detected in 65 of 100 groundwater samples and small amounts of the sweetener were also present in tap water. The levels detected are not considered detrimental to human health and were far too low to change the taste of the water.

The study has been published in the journal Environmental Science & Technology .