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 nonagricultural 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," says the study's lead author, Rolf U. Halden,
assistant professor in 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, 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 bioaccumulate in the food chain,
but at this point we can only speculate," Halden says,
adding that more research is needed to determine whether
the environmental contamination discovered translates into
human exposure and any corresponding long-term risks.
Prior to 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. Halden and his
summer research intern, Daniel H. Paull, now a graduate
student in the Chemistry Department in the Krieger School
of Arts and Sciences, analyzed water samples taken from
rivers in and around Baltimore, 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," Halden says. "Further
studies are needed to determine the effect of triclocarban
on aquatic life and potential pathways of unwanted human
exposure."
The study was written by Halden and 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.