May 20, 2008
Related ArticlesAntimicrobial Soaps and Environmental Pollution
Much has been made of how the overuse of antibacterial products may negatively affect human health. However, new research indicates that the active ingredients of antibacterial products may also have a negative impact on the environment. Researchers at the Biodesign Institute at Arizona State University have traced the active ingredients of soaps—including the antimicrobial compounds triclosan and triclocarbon—to sediment deposits in Jamaica Bay, located off the tip of Long Island in New York and the Chesapeake Bay, located off the coast of Maryland and Virginia. Some of these additives can be traced back to as early as the 1960s.
"Our group has shown that antibacterial ingredients used a half a century ago, by our parents and grandparents, are still present today at parts-per-million concentrations in estuarine sediments underlying the brackish water into which New York City and Baltimore discharge their treated domestic wastewater," said Rolf Halden, the lead researcher on the project. "This extreme environmental persistence by itself is a concern, and it is only amplified by recent studies that show both triclosan and triclocarbon to function as endocrine disruptors in mammalian cell cultures and in animal models."
Researchers analyzed vertical core samples of sediment taken from two locations on the East Coast. The scientists noted that both triclocarbon and triclosan persist over time in estuary sediments. Triclocarbon proved to be more persistent than triclosan, as it is present in parts-per-million levels. Such amounts may be harmful to aquatic life such as bottom feeders including shellfish and crabs. Biomagnification, or the accumulation of a pollutant in higher concentrations as it moves up the food chain, may also be a concern.
During their study, the researchers found that certain anaerobic microorganisms that live in the sediments assist in the breakdown of the antimicrobial compound triclocarbon by pulling off chlorine atoms from the carbon chain one at a time to obtain energy. While this is helpful to the environment, there exists much more contamination than can easily be taken care of by the tiny chlorine-consuming organisms.
"If we continue to use persistent antimicrobial compounds at the current rate, we are outpacing nature's ability to decompose these problematic compounds," said Halden. "The irony is that these compounds have no measurable benefit over the use of regular soap and water for hand washing; the contact time simply is too short."