Antibacterial Products Promote Bacterial Resistance in US Waterways

A popular synthetic antibacterial compound called triclosan is fueling the development of resistant bacteria in US waterways, according to research published in the journal Environmental Science and Technology.

This study marks the first time triclosan resistance has been documented in a natural environment.

Triclosan is an ingredient found in a range consumer products, added to reduce or prevent bacterial contamination. Originally invented for use by surgeons in the 1960s, triclosan can now be found in clothing, kitchenware and toys, as well as common antibacterial soaps, bodywashes, toothpastes and some cosmetics, according to the US Food and Drug Administration. About one half of all liquid soaps sold in the US contain the synthetic antibacterial.

Triclosan can enter water systems such as streams and rivers via domestic wastewater systems, leaky sewer infrastructure and sewer overflows. Residues of triclosan in US waterways are now common in the United States, the researchers report.

"The bacterial resistance caused by triclosan has real environmental consequences. Not only does it disrupt aquatic life by changing native bacterial communities, but it's linked to the rise of resistant bacteria that could diminish the usefulness of important antibiotics," said study author Emma Rosi-Marshall, an aquatic ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York.

Working out of three sites in the Chicago metropolitan regions, researchers explored how bacteria living in stream and river sediments responded to triclosan in both natural and controlled settings. Field studies were conducted at the urban North Shore Channel area, the suburban West Branch Dupage River, and rural Nippersink Creek.

In the most urban areas there was a correlation with a rise in triclosan levels and a rise in bottom dwelling bacteria resistant to triclosan.

The research team found that untreated sewage released by combined sewer overflows -- where one pipe carrying residential and industrial wastewater and storm water exceeds its capacity, usually because of excessive rain or snowmelt -- are a major source of triclosan pollution in Chicago's North Shore Channel.

"We detected much lower levels of triclosan at a site downstream of a sewage treatment facility as compared to a site downstream of combined sewer overflows. And we demonstrated a strong link between the presence of triclosan in the environment and the development of triclosan resistant bacteria," said senior research author John Kelly of Loyola University Chicago .

The findings also support the idea that tricosan can be effectively removed from wastewater at sewage treatment plants, provided overflow does not cause triclosan-laden water to bypass the treatment facilities.

Laboratory experiments that simulated stream and river flow confirmed what the researchers observed in the field: abundant triclosan exposure triggers an increase in triclosan-resistant bacteria.

Earlier this week consumer products giant Proctor & Gamble (P&G) announced plans to eliminate triclosan and the chemical diethyl phthalate (DEP) from all its products by 2014.

Johnson & Johnson has also pledged to eliminate triclosan from its products by 2015, the Huffington Post reported.

The FDA states the triclosan has not been conclusively proven to actually kill bacteria, despite claims advertised on anti-bacterial products purporting they do.

"At this time, the agency does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water," the FDA states on its triclosan information page.