Minnesota becomes the first state in the US to ban soaps containing the common antibacterial agent, called triclosan. The impact is already being felt nationwide.
The federal government's ban on triclosan takes effect September 2017 and many major manufacturers have phased out the germ-killing chemical.
For nearly a decade, researchers at the University of Minnesota have been studying the levels of triclosan and its degradation products in freshwater lakes and rivers.
In 2010, Arnold authored a study showing that specific harmful chemical compounds, called dioxins, derived from the antibacterial agent triclosan account for an increasing proportion of total dioxins in Mississippi River sediments.
Another study by Arnold in January 2013 determined that triclosan is found in increasing amounts in several Minnesota freshwater lakes. Arnold and his colleagues also found an increasing amount of other chemical compounds, called chlorinated triclosan derivatives, that form when triclosan is exposed to chlorine during the wastewater disinfection process. When exposed to sunlight, triclosan and its chlorinated derivatives form dioxins that persist in the environment.
In March 2013, Minnesota Gov. Mark Dayton ordered all state agencies to stop buying products that contain the chemical compound triclosan. Arnold testified in a legislative hearing in 2013 when a statewide ban was first proposed. In May 2014, the Minnesota Legislature passed a bill prohibiting retail sale of consumer cleaning products containing triclosan that goes into effect statewide on Jan. 1, 2017.