Artificial sweetener makes ideal tracer through the human body relatively unscathed and so are usually present in raw wastewater coming into treatment plants. The team took 24-hour composite samples from 10 wastewater treatment plants and examined 4 rivers, 9 lakes, and 100 groundwater samples. IGNAZ BUERGE
Ignaz Buerge of the Swiss Federal Research Station, Agroscope, and his colleagues first came across acesulfame as a potential wastewater tracer in 2008, while searching for a compound that would help pinpoint a leak from a wastewater treatment plant in Adliswil, Switzerland. During routine plant maintenance, sewage was inadvertently released into already-purified drinking water, and for two days residents had to boil their tap water. While investigating water samples from the incident, “we basically stumbled over” artificial sugars as a tracer, says coauthor Thomas Poiger of Agroscope. The researchers report their findings on four manufactured sweeteners in ES&T (DOI 10.1021/ es900126x). They argue that acesulfame, which is persistent in surface and groundwater, has the right characteristics to be used as a tracer for human wastewater. The finding will be useful for many scientists, the researchers note. “This paper appears to solve (or partially solve) one of the most vexing problems that several research communities have been [attempting to solve for] several years,” commented Bruce Brownawell of the State University of New York Stony Brook, in an email. Several compounds have surfaced as potentially appropriate tracers to follow the movement of wastewater from sewage or treatment plants into the environment. Caffeine once seemed to fit the bill, but it’s too easily degradable. Carbamazepine, an anticonvulsant that is persistent in the environment, is used as a pharmaceutical tracer in groundwater, but relatively low consumption rates may limit its usefulness. Acesulfame may be just right, Buerge and his coauthors say. The team tested four sugar substitutes: acesulfame, cyclamate (no longer approved in the U.S. but in use in Europe), saccharin, and sucralose. These substances pass
Coauthor Thomas Poiger of Agroscope recently sampled water from Lake Zurich. Poiger was part of a team that tested rivers, lakes, and groundwater for artificial sweeteners, in a search for tracers of human wastewater in the environment.
This is one of the first reports of high levels of some of these sugar substitutes in surface waters, the authors say. Sucralose has been detected at relatively high levels in other studies: the Swedish government reported its presence in lakes last year, and the Joint Research Centre of the European Commission recently reported relatively high levels in many of Europe’s rivers. The environmental impacts of artificial sugars remain to be studied. Buerge’s team found concentrations of the sweeteners at levels ranging from 2 to 65 micrograms per liter in untreated wastewater. The numbers indicate a fairly con-
4220 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / June 15, 2009
stant stream of artificial sugars passing through treatment plants and into surface water, the researchers concluded. The treatment process removes some saccharin and cyclamate, but not acesulfame and sucralose, they found. But acesulfame was the only sweetener the team detected in groundwater samples. Because it is present at higher concentrations and is persistent enough to be carried underground, the researchers propose that of the four sugars, acesulfame would make the best tracer. “We were always looking for a very hydrophilic and stable compound,” says Poiger. Acesulfame may even be too stable in some cases, he says: it occurs in both treated and untreated wastewater, making it harder to distinguish among contamination sources. Artificial sweeteners provide “a new twist” to identifying contaminants for possible use as humanwaste tracers, says Susan Glassmeyer of the U.S. EPA’s Office of Research and Development. If an artificial sugar has been approved for human consumption by food agencies, it is likely not a problem for human health, Glassmeyer says. But artificial sweeteners could serve as a good indication of the presence of human pathogens or other wastewater contaminants in groundwater and surface water. “I was surprised at how high the concentrations were,” she adds, noting that they were a few orders of magnitude greater than the levels of pharmaceuticals in water found by other researchers. Because of the sweeteners’ higher concentrations, analytical chemists “need less water to detect them,” Glassmeyer notes. On the downside, Buerge’s team uses an advanced analytical method, which is expensive. That extra cost could mean that a beach manager may not be able to afford to use acesulfame as a fecal contamination indicator, she comments. —NAOMI LUBICK
10.1021/es901127x
2009 American Chemical Society
Published on Web 05/07/2009
