MINNEAPOLIS, May 24 (UPI) -- U.S. researchers say they've found increasing dioxin levels from the antibacterial agent triclosan in Mississippi River sediments.
University of Minnesota scientists said the levels of the four dioxins derived from triclosan -- used in many hand soaps, and other consumer products -- have risen as much as 300 percent during the last 30 years, while levels of all other dioxins have dropped by up to 90 percent.
The study by Professors William Arnold and Kristopher McNeill and researcher Jeff Buth focused on sediment core samples from Lake Pepin, an enlargement of the Mississippi River 60 miles downstream from the Minneapolis-St. Paul metro area.
The sediment cores, containing a record of pollutant accumulation in the lake for the past 50 years, were analyzed for triclosan, the four dioxins derived from triclosan, and the entire family of dioxin chemicals.
"These four dioxins only come from triclosan. They didn't exist in Lake Pepin before triclosan was introduced," Arnold said. "In the most current sediments, the triclosan-derived dioxins account for about 30 percent of the total dioxin mass."
Triclosan was first added to commercial liquid hand soap in 1987, and by 2001 about 76 percent of commercial liquid hand soaps contained it, the researchers said.
The study -- a collaboration with Pace Analytical Services Inc., the Science Museum of Minnesota and Virginia Tech -- appears in the May 18 online edition of the journal Environmental Science and Technology.
