Triclosan in Illinois Rivers and Streams

from left to right: one chloride bond on the first and third carbons of a carbon ring, oxygen bonds the fourth carbon of the carbon ring to another carbon ring at the first carbon in the ring with a hydroxyl group on the second carbon and a chloride at the fourth carbon in the ring.

Chemical Structure of Triclosan

Several large-scale surveys by USGS and others have detected a large number of pharmaceuticals and personal care products (PPCPs), including antibiotics, in U.S. streams. However, relatively little is known about the ecological impacts of these biologically active compounds. Analytical Chemist John Scott from ISTC, along with colleagues from Loyola University, Chicago, and Cary Institute of Ecosystem Studies, Millbrook, NY, focused on examining potential effects of triclosan, a broad-spectrum antimicrobial compound that is incorporated into numerous consumer products, on the aquatic environment.

Triclosan has been detected in numerous waterways across the U.S., and because of its widespread use, concerns are being raised about its potential ecological effects. The researchers conducted a field survey and an artificial stream experiment to assess effects of triclosan on benthic bacterial communities. Field sampling indicated that triclosan concentrations in stream sediments increased with degree of urbanization. There was a significant correlation between sediment triclosan concentration and the proportion of cultivable benthic bacteria that were resistant to triclosan, demonstrating that the levels of triclosan present in these streams were affecting native communities. Sources for triclosan contamination included domestic wastewater traced to broken pipes and releases of untreated wastewater during high rain fall events. Also low-dose chronic contamination occurred because many wastewater treatment plants are not able to completely remove triclosan from their effluents before it is discharged to waterways.

antibacterial soap showing drug facts and the active ingredient is triclosan

An artificial stream experiment confirmed that triclosan exposure could trigger increases in triclosan resistance within cultivable benthic bacteria, and pyrosequencing DNA analysis indicated that triclosan resulted in decreased benthic bacterial diversity and shifts in bacterial community composition. One notable change was a sixfold increase in the relative abundance of cyanobacterial sequences and a dramatic die-off of other algae within the artificial streams. Selection of cyanobacteria over other algae could have significant implications for higher trophic levels within streams.

Finally, the researchers observed no effects of triclosan on bacterial abundance or respiration rates, suggesting that bacterial density and function were highly resilient to triclosan exposure.

Due to growing concerns about the ubiquitousness of triclosan in the environment, the Illinois House is considering a bill (HB3462) to ban triclosan in personal care and other household products. Minnesota became the first state to ban triclosan in 2014. Japan and Canada also have bans on triclosan because of concerns about health and environmental impacts.

This project was funded by the Illinois Hazardous Waste Research Fund.