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Triclosan pollutes Minnesota lakes, U of M study finds

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Grand Marais lighthouse
The lighthouse and western breakwater beacon mark the entrance to the Grand Marais harbor.Lake Superior is among the bodies of water in which triclosan, a common antibacterial agent used in soaps and other products, has been detected by a new University of Minnesota study.
Bryan Hansel for MPR

Increasing amounts of triclosan, a common antibacterial agent used in soaps and other products, has been detected in Minnesota lakes, according to the results of a new University of Minnesota study. 

The researchers studied sediment in eight Minnesota lakes of varying size: Lake Pepin, Lake St. Croix, Lake Winona, East Lake Gemini, Lake Shagawa, Duluth Harbor, Lake Superior and Little Wilson Lake. Some of the sediment dated back more than 100 years.

When the researchers analyzed the chemicals in that sediment, they discovered increased concentrations of triclosan and its byproducts since the chemical was patented in 1964 and entered the market in the 1970s. Triclosan is added to everything from cosmetics to toothpaste to dishwashing soap. 

The study was published Tuesday in the journal, Environmental Science and Technology.

The concentrations of triclosan varied among the lakes. Larger lakes with many wastewater sources had increased concentrations of the chemical and its byproducts since triclosan entered the market. Factors in the triclosan concentration in smaller lakes with a single wastewater source included the extent of triclosan use and changes in water treatment practices. For example, one lake showed decreased concentrations of a triclosan byproduct when UV disinfection technology replaced chlorine at the local wastewater treatment plant.

Although the study did not evaluate triclosan's effect on lakes' health, environmentalists have raised questions about the chemical's use. When triclosan is exposed to chlorine during wastewater disinfection and then exposed to sunlight, the byproduct can form dioxins that have potential toxic effects, researchers said. Such dioxins were also detected in the lakes during the study.

The study's lead author, William Arnold, said he hopes the research will encourage consumers to read product labels to know if the products they buy contain triclosan. 

"It's important for people to know that what they use in their house every day can have an impact in the environment far beyond their home," Arnold, a University of Minnesota civil engineering professor, said in a news release.

The U.S. Food and Drug Administration and the federal Environmental Protection Agency are studying the effects of triclosan on health and the environment.

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