PCBs, DDT, and PBDE’s Found in Marine Mammal Brains

PCBs, DDT, and PBDE’s Found in Marine Mammal Brains

Tuesday, May 26th, 2009

A Woods Hole grad student, Eric Montie, now working at the University of Southern Florida’s Mann Lab for Marine Sensory Biology, has released the finding from a study he conducted on marine mammal brains, and the news is not good. It seems that human’s propensity to use the oceans as a dumping ground (as well as our ineptitude in realizing that dangerous chemicals don’t just go away when we no longer see them) has resulted in bio-accumulation of some nasty substances in marine mammals.

Yes, again with the flame retardants…

Eric Montie went to work with Environment Canada to “learn the painstaking techniques required to extract and to quantify more than 170 different pollutants and their metabolites.” He brought back the methods to Woods Hole and started analyzing the brains of 11 whales and dolphins and a grey seal. The animals came from around the Cape Cod area, and darned if you didn’t guess, some not-so-nice chemicals were present in the cerebrospinal fluid as well as the grey matter.

And yes, our dear friends DDT, an overly effective pesticide that has been banned around the world, but doesn’t seem to want to go away; PBDEs, or flame retardants which are only know being scrutinzed despite their ubiquity; and PCBs, again a banned chemical family that just doesn’t go away have all been found in the marine mammalian brain studied by Montie. In fact, the levels of PCBs in the seal were in the parts per million, which may seem small, but according to Montie, “you rarely find parts per million levels of anything in the brain.”

So what’s the big deal? Well, PCBs kind of trick a body into thinking that they are thyroid hormones and instead of healthy and needed thyroid hormones, the body gets PCBs. That can lead to all sorts of neurological issues and problems when it comes to brain development and can disrupt the sensory functions of mammals like dolphins, seals and whales that really depend on their sense of hearing to live.

Just how these chemicals might impact marine mammal health is something Montie plans to pursue. This summer, Montie, [David] Mann [the man behind the aforementioned Mann Lab], 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.”