Canadian researchers think they have found a great way to trace the travels of treated sewage after it is discharged into rivers: Follow the artificial sweeteners.

The scientists found elevated concentrations of four sweeteners - cyclamate, saccharin, sucralose, and acesulfame - in water samples collected along the length of the Grand River in Ontario.

Commonly used in diet drinks, the sweeteners got into the Grand by way of the 30 sewage treatment plants that empty into the river and its tributaries.

The research, published Dec. 11 in the online journal PLOS ONE, adds to a growing body of evidence that people are spiking waterways and their drinking supplies with an array of compounds that pass through not just them, but even advanced treatment systems.

Antidepressants, antibiotics, steroids, and fragrances are among the products that have been detected in surface waters. Some of the contaminants have been found in fish tissue. Some compounds not only get through sewage plants, they also survive purification of drinking supplies and have been measured in trace amounts in municipal tap water.

The researchers made no attempt to gauge the ecological effects of sweetening a river, which they said were largely unknown. - L.A. Times