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Soaps linked to chemical build-up in Lake Pepin

A new study has found a link between household antibacterial soaps and the accumulation of potentially harmful chemicals in the Mississippi River that could pose environmental threats.

The University of Minnesota study, released this week, examined sediment samples from Lake Pepin, which allowed researchers to analyze the accumulation of pollutants over time.

Researchers found over the past 50 years dioxins - described by U of M Civil Engineering Professor William Arnold as a "generally nasty (class of) chemicals" - had in all cases decreased, with the exception of those derived from triclosan, an ingredient found in some hand and dish soaps and deodorants.

"These four dioxins only come from triclosan. They didn't exist in Lake Pepin before triclosan was introduced," said Arnold, who supervised the study, in a university press release.

Dioxins that end up in the Mississippi by the way of triclosan, an antibacterial agent first added to soaps in 1987, has risen between 200 to 300 percent in recent decades, according to the study.

Just exactly how toxic these four dioxins are or the specific impacts they might have on the environment is not well understood, Arnold said, but because of the nature of the chemicals there is reason to be concerned.

In April, the Food and Drug Administration announced it would begin studying the safety of triclosan. To date the chemical has not been found harmful to human health, but has been linked to hormonal disruptions in animals and bacterial resistance to antibiotics.

Triclosan enters the environment most often through household use. When soap or another product containing triclosan washes down the sink it is carried to a municipal wastewater treatment plant where a process rids water of most of the triclosan; but some remains in the water and enters the environment.

Equipping a wastewater treatment plant to catch all the triclosan that passes through would be very expensive, said Bob Stark, Red Wing Public Works deputy director of utilities.

"It's not even in the realm of being feasible," Stark said of the costs that would entail.

A more practical solution rests in the grocery store, Arnold told the R-E. He said, "An easier way is for people to change their consumer habits."

On its website, the FDA says it does not have enough evidence to recommend consumers avoid products that contain triclosan.

The study was a collaboration between the U of M, the Science Museum of Minnesota, Pace Analytical and Virginia Tech. It is available online at //

Jon Swedien is a reporter at the Red Wing (Minn.) Republican Eagle, which is owned by Forum Communications Co.