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Dolphins absorb PCBs -

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Dolphins absorb PCBs

Dolphins in the Georgia estuarine environment have been found to be accumulating and harbouring
critical levels of PCB contaminants. This has led to altered thyroid hormones and suppressed immune
function. Despite numbers being maintained, it's thought the dolphins are living on the edge and
could experience mass die-off if stressed. If humans share the same food as dolphins, these
contaminants could be harming people as well.


Robyn Williams: Dolphins are absorbing tiny waste particles; PCBs from the electronics industry
ending up in the ocean. Lori Schwacke, principal scientist with NOAA in Charleston, says they've
now measured the highest levels ever in these creatures.

Lori Schwacke: We found that most of the dolphins had relatively limited ranges and that the
contaminants are most likely being dispersed through the coastal food web. From the health exams we
found a number of indications of compromised health, including altered thyroid hormones and
suppressed immune function. The results from this research are significant from two perspectives.
First, they underscore the importance of monitoring the health of marine wildlife. From simple
appearance the Georgia estuarine dolphin stock is thriving or at least sustainable, but in reality
many of these dolphins are living on the edge. The fact that they're harbouring critically high
burdens of chemicals with known toxic effects suggests that they are extremely vulnerable to
further stressors. A viral or bacterial pathogen could push them over the edge, initiating an
epidemic which devastates the stock. A number of disease epidemics have previously resulted in mass
die-offs of dolphins or other marine mammals, and exposure to legacy contaminates such as PCBs
contributed to these die-offs and exacerbated the effects.

Our findings are also significant from a human health perspective. We've demonstrated that PCBs
which have leached into the Georgia estuaries are not simply settling into the marine sediments
near the site or being washed into the ocean where they're diluted, they're making their way into
the coastal food web. The extreme concentrations measured in these dolphins prompts questions about
the potential chemical hazards for people who consume local seafood, and this certainly warrants
further investigation.

NOAA and its partners are continuing studies of potential ecological impacts, and the National
Centre for Environmental Health, part of the Centre for Disease Control and Prevention, is now
planning a pilot study which will investigate exposures to PCBs and other contaminates among
members of Georgia coastal communities who eat locally caught seafood. The CDC researchers would
like to understand whether marine mammal populations and human communities sharing the same seafood
resources experience similar exposures. Thank you.

Robyn Williams: Lori Schwacke with NOAA, the National Ocean Service, with a warning about massive
PCB residues in dolphins.