Dolfijnen voor kust Georgia (VS) ziek door hoge graad chemicaliën (pcb's) in vet van de dieren

Coastal dolphins sickened by high levels of chemicals

22-02-2010 By Bo Petersen - The (Charleston) Post and Courier, The Sun News, USA


Dolphins are getting sick from eating the same fish we do.
That's the disturbing conclusion of the latest round of federal research at the National Oceanic and Atmospheric Administration offices at Fort Johnson, among other sites.

Studies of dolphins in coastal Georgia discovered some of the highest levels of PCBs ever found in the fat of a marine mammal, 30 years after the use of the toxic industrial insulating compound was banned.

"Some of these [dolphins] are living on the edge," said Lori Schwacke, principal scientist at the NOAA Oceans and Human Health Center of Excellence at Fort Johnson. Their immune systems have been suppressed to the point where the outbreak of a single virus could result in mass kills, she said.
"While we don't understand the risk to people yet, it's enough of a red flag to make us want to do further experimentation."

The study is joined by studies of dolphins and sea lions in California, as well as controlled laboratory studies of rats, that show a connection between how these animals develop diseases, such as epilepsy, and how people do.

Studies also found that dolphins develop diabetes and have been exposed to the human papillomavirus. Those discoveries could lead to new treatments for the diseases in people.

Dolphins first were studied in an area around Brunswick, Ga., the location of four federal Superfund contamination sites. But when researchers moved to an estuarine research reserve some 30 miles away, expecting to find healthy dolphins to use as a control population, they found PCB levels just as high.

Because dolphins tend not to roam, the finding suggests that they were getting the chemical from fish they ate; the fish do roam.
"The contaminants aren't settling in the sediment or moving out in the ocean. They're actually moving into the coastal food web," Schwacke said.
"And the levels we're seeing in these animals is just incredibly high."

Dolphins eat far more fish than people do, but "with people we care about much lower levels and effects" of contamination.
"We don't want to tell people to stop eating seafood; there are health benefits to eating seafood. It's definitely enough of worry to prompt additional study," she said.

Finding those levels of PCB after 30 years suggests "the things we're doing to our coast now are going to be around for decades."

The National Center for Environmental Health is studying contamination levels and the health of people who live along that coast.

The research of Schwacke's team has been supplemented by studies showing that sea lions exposed to a certain kind of algal bloom not only have seizures, but 19 of every 20 of the mammals develop epilepsy months later.
The research studied sea lions in the wild and conducted experiments on laboratory rats.

"We know this is what happens in laboratory cultures. We infer it happens in the environment as well," said John Ramsdell, harmful algal bloom and analytical response chief at the National Centers for Ocean Science at Fort Johnson.

The chemical produced in the bloom is naturally occurring, but manmade chemicals, such as fertilizer nutrients, worsen it, he said.
The chemical was thought to be found only on the West Coast until monitoring by a high school science class in coastal North Carolina discovered it. It's been linked to pygmy sperm whale strandings, which occur regularly along the East Coast.
As an odd aside, the chemical caused a sea bird die-off in coastal California that was developed in the Alfred Hitchcock classic movie "The Birds."

Meanwhile, National Marine Mammal Foundation researchers have found that dolphins naturally develop adult-onset diabetes and complications similar to people. But the mammals seem to be able to turn the disease on and off as needed for their diet.
Learning about that "switch" might provide a treatment for the disease in humans.

And research at the University of Florida has found at least 50 new viruses in dolphins, far more than in any other marine mammal species, including the human papillomavirus that causes cervical cancer in people but doesn't appear to in dolphins.
Finding out why might suggest a treatment for that disease.

(Bron: http://www.thesunnews.com/)