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A team of Canadian researchers has detected high concentration levels of artificial sweeteners used in the food and beverage industry in the Grand River, near Ontario, suggesting that wastewater treatment plants are unable to remove them from the water supply system.

The study, published online in the journal PLOS One, found elevated levels of cyclamate, saccharin, sucralose and acesulfame — compounds used mostly in the production of diet drinks. Their presence adds to the series of compounds that various studies have found in drinking water supplies that raise concerns over the quality of water. Recent scientific research from different sources has detected antibiotics, antidepressants and steroids in water supplies but the potential long-term effect of exposure to them is not known.

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For their latest study, researchers from the University of Waterloo and from Environment Canada examined water samples from the Grand River, taken from 23 different locations at various distances from wastewater treatment plants. Results showed that cyclamate and saccharin were present in lower concentration levels than acesulfame and sucralose, most likely because the latter two were more difficult to remove.

However, researchers stated that measuring the environmental effect of artificial sweeteners in water was not a goal of their study. The actual impact they may have on aquatic life and on public health remains "largely unknown," academics said.