Posted Jan 31, 2011
Levels of dioxins associated with an antibacterial agent used in hand soaps, deodorants, dishwashing liquids and other consumer products have increased markedly in Lake Pepin, a University of Minnesota study shows.
The dioxins are derived from triclosan, which the university says has been linked to disruptions of hormonal function and may play a role in the evolution of bacterial resistance to antibiotics. The Food and Drug Administration is looking into its safety.
In a study appearing online in the journal Environmental Science and Technology, researchers from the university’s Institute of Technology found that over the past three decades, the levels of the four dioxins derived from triclosan have risen by 200 percent to 300 percent. All other dioxin levels, meanwhile, have declined by 73 percent to 90 percent.
In earlier research, university civil engineering professor William Arnold and a colleague discovered that triclosan, when exposed to sunlight, generated a specific suite of four dioxins.
In the current study, spearheaded by former university student Jeff Buth, researchers examined sediment core samples from Lake Pepin, a widening of the Mississippi River southeast of the Twin Cities.
The cores, which contain a 50-year record of pollutant accumulation, were analyzed for triclosan, the four dioxins derived from it, and the entire family of dioxin chemicals.
“In the deepest part of the sediment, there is no triclosan and these dioxins are
not present,” Arnold said. “Once triclosan was introduced, a record of triclosan and these four dioxins appears in the sediment.”
In use for four decades, triclosan was added to commercial liquid hand soap in 1987, and by 2001, about 76 percent of commercial liquid hand soaps contained it. About 96 percent of triclosan from consumer products goes down residential drains, and much of it eventually reaches wastewater treatment plants.
It is not completely removed during that stage, and when treated wastewater is released into rivers, sunlight converts some of the triclosan into dioxins.
Triclosan and the dioxins then end up in Lake Pepin sediments by sticking to organic particles, which sink in the calmer waters of the lake.
Arnold said neither the toxicity of the dioxins derived from triclosan nor the extent of the dioxins distribution in the environment is well understood.
Asked what message consumers should take from the study, he said, “It’s up to them to decide if they should be alarmed or not. If they are, the message is, read the labels on the products they buy.”
He didn’t recommend Lake Pepin anglers alter fish consumption based on the study.
“These compounds aren’t driving fish-consumption advisories, but it’s always good to follow fish-consumption advisories,” he said.
The study was a collaboration involving researchers at the University of Minnesota, Pace Analytical in Minneapolis, the Science Museum of Minnesota and Virginia Tech.
Dennis Lien can be reached at 651-228-5588.
Editor’s note: Purchase regular soap. It cleans and removes dirt and bacteria from hands just as well.
To see more of the Pioneer Press, or to subscribe to the newspaper, go to http://www.twincities.com.
Copyright © 2010, Pioneer Press, St. Paul, Minn.
Distributed by McClatchy-Tribune Information Services.
Levels of dioxins associated with an antibacterial agent used in hand soaps, deodorants, dishwashing liquids and other consumer products have increased markedly in Lake Pepin, a University of Minnesota study shows. The dioxins are derived from triclosan, which the university says has been linked to disruptions of hormonal function and may play a role in the evolution of bacterial resistance to antibiotics. The Food and Drug Administration is looking into its safety. In a study appearing online in the journal Environmental Science and Technology, researchers from the university's Institute of Technology found that over the past three decades, the levels of the four dioxins derived from triclosan have risen by 200 percent to 300 percent. All other dioxin levels, meanwhile, have declined by 73 percent to 90 percent. In earlier research, university civil engineering professor William Arnold and a colleague discovered that triclosan, when exposed to sunlight, generated a specific suite of four dioxins. In the current study, spearheaded by former university student Jeff Buth, researchers examined sediment core samples from Lake Pepin, a widening of the Mississippi River southeast of the Twin Cities. The cores, which contain a 50-year record of pollutant accumulation, were analyzed for triclosan, the four dioxins derived from it, and the entire family of dioxin chemicals. "In the deepest part of the sediment, there is no triclosan and these dioxins are not present," Arnold said. "Once triclosan was introduced, a record of triclosan and these four dioxins appears in the sediment." In use for four decades, triclosan was added to commercial liquid hand soap in 1987, and by 2001, about 76 percent of commercial liquid hand soaps contained it. About 96 percent of triclosan from consumer products goes down residential drains, and much of it eventually reaches wastewater treatment plants. It is not completely removed during that stage, and when treated wastewater is released into rivers, sunlight converts some of the triclosan into dioxins. Triclosan and the dioxins then end up in Lake Pepin sediments by sticking to organic particles, which sink in the calmer waters of the lake. Arnold said neither the toxicity of the dioxins derived from triclosan nor the extent of the dioxins distribution in the environment is well understood. Asked what message consumers should take from the study, he said, "It's up to them to decide if they should be alarmed or not. If they are, the message is, read the labels on the products they buy." He didn't recommend Lake Pepin anglers alter fish consumption based on the study. "These compounds aren't driving fish-consumption advisories, but it's always good to follow fish-consumption advisories," he said. The study was a collaboration involving researchers at the University of Minnesota, Pace Analytical in Minneapolis, the Science Museum of Minnesota and Virginia Tech. Dennis Lien can be reached at 651-228-5588. Editor's note: Purchase regular soap. It cleans and removes dirt and bacteria from hands just as well. To see more of the Pioneer Press, or to subscribe to the newspaper, go to http://www.twincities.com. Copyright © 2010, Pioneer Press, St. Paul, Minn. Distributed by McClatchy-Tribune Information Services.Tags: Clean, Deodorant, Food, Information
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