[Pharmwaste] Marine Mammals' Brains Exposed To Hazardous Cocktail Of PesticidesIncluding DDT, PCBs, Brominated Flame Retardants

Tenace, Laurie Laurie.Tenace at dep.state.fl.us
Fri May 22 11:13:02 EDT 2009


Marine Mammals' Brains Exposed To Hazardous Cocktail Of Pesticides
Including DDT, PCBs, Brominated Flame Retardants

ScienceDaily (May 21, 2009) - The most extensive study of pollutants in
marine mammals' brains reveals that these animals are exposed to a
hazardous cocktail of pesticides such as DDTs and PCBs, as well as
emerging contaminants such as brominated flame retardants.

Eric Montie, the lead author on the study currently in press and
published online April 17 in Environmental Pollution, performed the
research as a student in the Woods Hole Oceanographic Institution-MIT
Joint Graduate Program in Oceanography and Ocean Engineering and as a
postdoctoral fellow at the Woods Hole Oceanographic Institution (WHOI).
The final data analysis and writing were conducted at College of Marine
Science, University of South Florida, where Montie now works in David
Mann's marine sensory biology lab.

Co-author Chris Reddy, an associate scientist in the WHOI Marine
Chemistry and Geochemistry Department, describes the work as
"groundbreaking because Eric measures a variety of different chemicals
in animal tissues that had not been previously explored. It gives us
greater insight into how these chemicals may behave in marine mammals."

The work represents a major collaborative effort between the
laboratories of Reddy and Mark Hahn in the WHOI Biology Department,
where Montie was a graduate student and post doc, as well as Robert
Letcher at Environment Canada. Montie traveled to Environment Canada in
Ottawa to learn the painstaking techniques required to extract and to
quantify more than 170 different pollutants and their metabolites. He
then brought the methods back to WHOI and performed the analyses in
Reddy's laboratory. Reddy describes the methods as extremely unforgiving
and explains, "This is not making Toll House cookies. The fact that Eric
pulled it off so seamlessly is amazing considering that he did this by
himself far away from Ottawa."

Montie analyzed both the cerebrospinal fluid and the gray matter of the
cerebellum in eleven cetaceans and one gray seal stranded near Cape Cod,
Mass. His analyses include many of the chemicals that environmental
watchdog groups call the dirty dozen, a collection of particularly
ubiquitous pesticides that were banned in the 1970s because of their
hazards to human health. But the Montie study goes much further in the
scope of contaminants analyzed. And many of the contaminants are
anything but benign.

The chemicals studied include pesticides like DDT, which has been shown
to cause cancer and reproductive toxicity, and PCBs, which are
neurotoxicants known to disrupt the thyroid hormone system. The study
also quantifies concentrations of polybrominated diphenyl ethers or
PBDEs (a particular class of flame retardants), which are neurotoxicants
that impair the development of motor activity and cognition. This work
is the first to quantify concentrations of PBDEs in the brains of marine

The results revealed that concentration of one contaminant was
surprisingly high. According to Montie, "The biggest wakeup was that we
found parts per million concentrations of hydroxylated PCBs in the
cerebrospinal fluid of a gray seal. That is so worrisome for me. You
rarely find parts per million levels of anything in the brain."

The particular hydroxylated PCB found at these soaring concentrations,
called 4-OH-CB107, has some serious side effects. In rats, it
selectively binds to a carrier protein called transthyretin, which has
been found to be abundant in cerebrospinal fluid in mammals. This
protein plays a role in thyroid hormone transport throughout the brain,
though its exact role is not known. Thyroid hormone plays a key role in
the development of the brain, as well as sensory functions, in
particular hearing in mammals. Compromised hearing would have
significant impact for dolphins, because as Montie points out, "these
animals rely on hearing as their primary sensory modality to communicate
and to find and catch food."

Just how these chemicals might impact marine mammal health is something
Montie plans to pursue. This summer, Montie, Mann, and Dr. Mandy Cook
(from Portland University) will partner with scientists from NOAA to
test the hearing in dolphins living near a Superfund site in Georgia and
compare it to dolphins from locations where ambient concentrations of
pollutants are significantly lower. Montie is also working with Frances
Gulland, director of the Marine Mammal Center in Sausalito, CA, to
examine how California sea lions's exposure to PCBs may increase their
sensitivity to domoic acid, a naturally produced marine neurotoxin
associated with "red tides."

The work of Montie and his colleagues lays the groundwork for
understanding how environmental contaminants influence the central
nervous system of marine mammals. Montie sees this work as the forefront
of a new field of research, something that might be called
neuro-ecotoxicology. For years, most of the work in this area focused on
how concentrations of marine pollutants affected the animal's immune
system or its hormone systems. The research by Montie, Reddy, Hahn, and
their coauthors provides tools to ask deeper questions about how the
ever-growing list of contaminants in the ocean affect the neurological
development of marine mammals.

And what sort of results does Montie expect this new field of
neuro-ecotoxicology to produce? "I think we don't really know the brunt
of what we are going to see in wildlife."

This study was performed with funding form the WHOI Ocean Life
Institute, WHOI Marine Policy Center, Walter A. and Hope Noyes Smith,
and an EPA STAR fellowship. Supplemental funding was provided from the
Natural Science and Engineering Research Council (NSERC) of Canada (to
Robert Letcher), David Mann at the College of Marine Science, University
of South Florida, and a NOAA Oceans and Human Health postdoctoral
traineeship provided by Jonna Mazet (UC Davis Wildlife Health Center),
Kathi Lefebvre (Northwest Fisheries Science Center), and Frances Gulland
(The Marine Mammal Center).


Journal reference:

Eric W. Montie, Christopher M. Reddy, Wouter A. Gebbink, Katie E.
Touhey, Mark E. Hahn, Robert J. Letcher. Organohalogen contaminants and
metabolites in cerebrospinal fluid and cerebellum gray matter in
short-beaked common dolphins and Atlantic white-sided dolphins from the
western North Atlantic. Environmental Pollution, 2009; DOI:

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