Location: Bowdoin / Calendar

From triclosan to dioxins: How handsoap leads to an environmental problem

  • 11/8/2013 | 3:00 PM – 4:00 PM
  • Location: Druckenmiller Hall, Room 020
  • Event Type: Lecture

From  triclosan to dioxins: How handsoap leads to an environmental problem

Seminar: "From triclosan to dioxins: How your handsoap leads to an unanticipated environmental problem" by William Arnold of the University of Minnesota

Pharmaceuticals and personal care products (PPCPs) are widely used and through their normal course of use, often find their way into the sewage system. Wastewater treatment plants are not designed to remove trace chemicals, but a large fraction of the PPCPs are removed. The small fraction that is released into the environment, however, may have adverse effects. 

One ubiquitous PPCP is triclosan, the antimicrobial ingredient in liquid handsoaps. For triclosan, the major route to the environment is via wastewater effluents discharged to surface waters. During the disinfection of wastewater, chlorinated triclosan derivatives are produced. The impact of triclosan and related compounds is, in part, determined by their persistence in aquatic environments. 

Photolysis (reaction initiated by sunlight) is an important loss process for triclosan, and triclosan and chlorinated triclosan derivatives produce specific dioxins (a class of known toxic chemicals) in 1-3% yield upon exposure to sunlight.

Sediment cores serve as a record of contaminant release and accumulation in aquatic systems, and thus were collected across Minnesota to determine historical levels of triclosan and its degradation products. Analysis of sediment cores shows that while dioxins produced from incineration have been decreasing for the past thirty years, concentrations of dioxins derived from triclosan have been increasing and are correlated with triclosan concentrations/use.

The findings of this work suggest that the use of triclosan in consumer products merits additional scrutiny.