Anti-Bacterial Additive Found in Maryland Streams

A toxic chemical used in hand soaps, cleaners and other personal care products to kill germs is deposited and remains in the environment long after the products are used, according to researchers at the Johns Hopkins Bloomberg School of Public Health. The chemical—3,4,4’-trichlorocarbanilide (triclocarban), marketed under the trademark TCC™—is a non-agricultural polychlorinated phenyl urea pesticide that has been widely used for decades to kill bacteria. The researchers were among the first to detect concentrations of triclocarban in rivers and influent of wastewater treatment facilities. In some instances, they detected concentrations of triclocarban in waterways at levels 20-fold higher than previously reported. The study furnishes the first peer-reviewed environmental data of triclocarban contamination in U.S. water resources. It is published in the online edition of Environmental Science & Technology.

“Our study shows that environmental contamination with triclocarban is widespread but greatly underreported because conventional monitoring techniques cannot detect it,” said the study’s lead author Rolf U. Halden, PhD, PE, assistant professor of the School’s Department of Environmental Health Sciences and founding member of its Center for Water and Health. “We had to specifically develop a new method, termed liquid chromatography electrospray ionization mass spectrometry (LC/ESI/MS), to detect triclocarban in water. Using this new method, we found the disinfectant in all Maryland streams we examined. Now the big question is what are the ecological and human health consequences of triclocarban in the environment? From the chemical structure, one would expect the compound to concentrate in fish and bio-accumulate in the food chain, but at this point we can only speculate,” said Dr. Halden. He added that more research is needed to determine whether the environmental contamination discovered translates into human exposure and any corresponding long-term risks.

Prior to Dr. Halden’s research, the most recent data on the fate of triclocarban in wastewater were from 1975, and no peer-reviewed studies were conducted on the occurrence of the chemical in U.S. water resources. Dr. Halden and his summer research intern, Daniel H. Paull, now a graduate student in the Chemistry department at Johns Hopkins University, analyzed water samples taken from rivers in and around Baltimore, Md., as well as from local water filtration and wastewater treatment plants.

In these samples, the researchers detected triclocarban in river water at concentrations of up to 5.6 micrograms per liter (parts-per-billion) and in wastewater at 6.75 ppb. The highest detected concentrations in surface waters of the Greater Baltimore area were 20 fold higher than previously reported levels, which are currently used by the United States Environmental Protection Agency for evaluation of the ecological and human health risks of triclocarban. The antimicrobial was not detected in any samples of residential well water and municipal drinking water.

“It’s somewhat unsettling that we’ve been using this persistent disinfectant for almost half a century at rates approaching 1 million pounds per year and still have essentially no idea of what exactly happens to the compound after we flush it down the drain. Further studies are needed to determine the effect of triclocarban on aquatic life and potential pathways of unwanted human exposure,” said Dr. Halden.

“Analysis of Triclocarban in Aquatic Samples by Liquid Chromatography Electrospray Ionization Mass Spectrometry” was written by Rolf U. Halden and Daniel H. Paull.

The research was supported by the National Institute for Environmental Health Sciences through the Johns Hopkins Center in Urban and Environmental Health, the Johns Hopkins Bloomberg School of Public Health Faculty Innovation Award and the Johns Hopkins Center for a Livable Future.