How Diet Soda Can Be Used to Track Sewage

Fake sugar found in Ontario's tap water can be traced back to… sewage. Artificial sweeteners originating in diet soft drinks and foods survive a pretty remarkable journey through our bodies, down the toilet, through the wastewater treatment plant, into rivers, and, finally, into the water flowing out of the tap all over again.

The drinking water is still safe—it has been treated, after all, and these fake sugar levels are quite low—but for scientists it presents an intriguing possibility. What if the flow of wastewater could be traced with fake sugar? A high level of artificial sweeteners, for example, could signal a sewage leak nearby.

In a new study published in PLoS ONE, Canadian researchers traced four types of artificial sweeteners—cyclamate, saccharin, sucralose, and acesulfame—through Grand River Watershed in Ontario. There was so much fake sugar teeming in the waters that it could easily be used to track wastewater. Acesulfame, in particular, had all the characteristics of the perfect tracer.

How Diet Soda Can Be Used to Track SewageS

Ontario's Grand River

For one, there's a shit ton of it. Acesulfame potassium is a sweetener found in sugar-free foods such as Red Bull, Halls cough drops, and, most recently, Diet Pepsi. At one site, the levels of acesulfame in the river water measured was equivalent to 80,ooo to 190,000 cans of diet soda flowing past each day.

Just as acesulfame is not supposed to break down in your body—hence, zero calories—it is not degraded in the environment or wastewater treatment plant. There is also no natural source for acesfulfame, so there's no confusion about where it could have come from. If it's in your water, it came from sewage.

Other chemicals have been rejected as wastewater traces for various reasons, said John Spoelstra of Environment Canada, the lead researcher on the study. For example, caffeine breaks down in the environment; the seizure drug carbamazepine is too uncommon to use; and chloride can also come from road salt. "So far, artificial sweeteners are looking like the most ideal," he said.

Acesulfame can be used to not only trace leaks in the sewage system, but also to figure out how wastewater gets diluted as it moves through the watershed. Chemicals from pharmaceutical drugs, for example, also spread through the water, but they are degraded as well as diluted over time. By comparing the concentrations of potentially harmful drug compounds with that of acesulfame, researchers would have a better sense of how the drugs break down. The environmental impact of artificial sweeteners themselves, however, is still unknown.

Flushing the toilet is usually an act of expunging—of getting rid of the nasty shit. But what goes down has a way of coming back to haunt us. Call it the return of the repressed. Municipal sewage is a watery record of our collective habits, from illegal drug use to our sex lives. Our dieting habits, too. And if we're clever about it, we can turn it back to track what's happening to our waste.

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