[Pharmwaste] Study Shows Persistent Nature of Antimicrobials (triclosan and triclocarban)

DeBiasi,Deborah dldebiasi at deq.virginia.gov
Tue Jun 10 15:04:16 EDT 2008


http://www.eponline.com/articles/62911/

Study Shows Persistent Nature of Antimicrobials
May 22, 2008

The active ingredients of anti-bacterial soaps and cleaning agents have
come under scrutiny by the U.S. Environmental Protection Agency and the
U.S. Food and Drug Administration, due to both environmental and human
health concerns.

Two closely related antimicrobials, triclosan and triclocarban, are at
issue. Triclosan (TCS) has a structural resemblance to dioxin, and
triclocarban (TCC) is one of the top 10 pharmaceuticals and personal
care products most frequently found in the environment and in U.S.
drinking water resources.

Researcher Rolf Halden and co-workers at the Biodesign Institute at
Arizona State University have traced the active ingredients of soaps -
used as long ago as the 1960s - to their current location, the shallow
sediments of New York City's Jamaica Bay and the Chesapeake Bay, the
nation's largest estuary.

"Our group has shown that antimicrobial 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 waters into which New York City and Baltimore discharge their
treated domestic wastewater," said Halden, a new member of the
institute's Center for Environmental Biotechnology. "This extreme
environmental persistence by itself is a concern, and it is only
amplified by recent studies that show both triclosan and triclocarban to
function as endocrine disruptors in mammalian cell cultures and in
animal models."

Aiding in his team's research was another type of contamination: the
radioactive fallout from nuclear testing conducted in the second half of
the last century. Using the known deposition history and half-lives of
two radioactive isotopes, cesium-137 and beryllium-7, Halden and his
collaborators Steven Chillrud, Jerry Ritchie, and Richard Bopp assigned
the approximate time at which sediments observed to contain
antimicrobial residues had been deposited in the two East Coast
locations.

By analyzing vertical cores of sediment deposited over time in the two
sampling locations on the East Coast, they showed that TCC, and to a
lesser extent, TCS, can persist in estuary sediments. TCC was shown to
be present at parts per million levels, which could represent unhealthy
levels for aquatic life, especially the bottom feeders that are
important to commercial fishing industries like shellfish and crabs.

In the Chesapeake Bay samples, the group noticed a significant drop in
TCC levels that corresponded to a technology upgrade in the nearby
wastewater treatment plant back in 1978. However, earlier work by the
team had shown that enhanced removal of TCC and TCS in wastewater
treatment plants leads to accumulation of the problematic antimicrobial
substances in municipal sludge that often is applied on agricultural
land for disposal. Lead author Todd Miller concludes that "little is
actually degraded during wastewater treatment and more information is
needed regarding the long-term consequences these chemicals may have on
environmentally beneficial microorganisms."

Along the way of studying the deposition history of antimicrobials in
sediments, the team also discovered a new pathway for the breakdown of
antimicrobial additives of consumer products. Deep in the muddy
sediments of the Chesapeake Bay, they found evidence for the activity of
anaerobic microorganisms that assist in the decontamination of their
habitat by pulling chlorine atoms one by one off the carbon backbone of
triclocarban, presumably while obtaining energy for their metabolism in
the process. "This is good news," said Halden, "but unfortunately the
process does not occur in all locations and furthermore it is quite
slow. If we continue to use persistent antimicrobial compounds at the
current rate, we are outpacing nature's ability to decompose these
problematic compounds."

While combining bioenergy production and pollutant destruction has its
own appeal, Halden sees a simpler solution to combating the pollution
his team discovered: limit the use of antimicrobial personal care
products to situations where they improve public health and save lives.





Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032



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