Sucralose, the artificial sweetener in Splenda, is one tough molecule.

The chemical passes right through the body, then through sewage treatment systems and out into surface and ground waters looking the same as it did when it was stirred into a cup of coffee.

No one knows how the ever-greater amounts of sucralose release into the environment affect the ecosystem. But research published in Environmental Engineering Science shows that the artificial sweetener is indeed making it through traditional water filtering systems.

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The study’s authors, Arizona State University researchers Cesar Torres and Rosa Krajmalnik-Brown, recently studied the path sucralose follows from humans to rivers and other bodies of water.

  “Sucralose is a chlorinated sugar. Some of my work focuses on bioremediation of chlorinated organics,” says Krajmalnik-Brown in an ASU press release. “I know that many are toxic and they are more difficult to biodegrade than the non-chlorinated counterparts. Because of this, I became interested in sucralose and its fate in the environment.”

Samples of wastewater were taken from seven wastewater-processing plants in Arizona. For at least 48 days, the water was run through both anaerobic and aerobic biological batch reactors, systems designed to use natural processes to break down wastes. None of the samples showed a significant decrease in the amount of sucralose present.

Another set of experiments looked at the effects of chlorine, ozone, and ultraviolet light on the sucralose. Those three methods are used in the final stages of wastewater treatment, but none proved effective at breaking down sucralose.

The resilience of sucralose may be a good thing in some ways. The researchers note that its resistance to degradation keeps it from breaking down into highly toxic chlorinated compounds.

Sucralose could even be used to label water sources and trace wastewater as it flows into the environment.

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Sucralose is already in more than 4000 products and the number of new products containing it increased by 14 percent in 2010. As the artificial sweetener continues to grow in popularity, we may want to keep an eye on where it ends up. It may well be there for a long time.

IMAGE 1: Splenda packets (Getty Images).

IMAGE 2: The sucralose molecule (Wikimedia Commons).

IMAGE 3: The outlet of the Karlsruhe sewage treatment plant flows into the Alb River in Germany’s Black Forest. (Wikimedia Commons).