Contact:
Karunthachalam Kannan
(517) 353-9420
Sue Nichols
Media Communications
(517) 355-2281
CHEMICAL IS CULPRIT IN DEATH OF SEA OTTERS
EAST LANSING, Mich. - The partial ban on a compound used to keep barnacles off of boat hulls doesn't seem to be enough to save the lives of California sea otters, according to a recently published Michigan State University study.
An MSU research associate, Kurunthachalam Kannan, has found high concentrations of the chemical tributyltin - known as TBT - in the tissues of dead otters that had fed around harbor areas. The study appears in the May 1 edition of Environmental Science and Technology.
"This chemical has more immune suppressing potential than DDT or PCBs, and both of those chemicals are banned," Kannan said. "People thought 10 years ago that a partial ban would solve the problem - it appears that it has not."
TBT was commonly painted on boat hulls to keep away barnacles. It was banned from small boats in 1989, but still is used on ships and some international vessels. The chemical leaches out of the paint and settles into ocean sediment, where bottom-feeding otters eat mollusks and other shellfish. The otters studied were taken from harbors that spanned from Montara Beach near San Francisco down to Coal Oil Point near Santa Barbara.
The otters that had died of diseases - such as bacterial infections - had high concentrations of TBTs in the liver, kidney and brain, Kannan found. Healthy otters - those that had died of trauma rather than disease - did not.
No one knows precisely how long it takes TBT to degrade in the environment - Kannan said it likely is up to 10 years. TBT and its degradation by products have been shown to suppress the immune systems of mammals and fish - leaving the animals susceptible to infections and illness. TBT binds to proteins and goes directly to an animal's vital organs.
The work, which comes out of the National Food Safety and Toxicology Center at Michigan State, was supported by MSU through a cooperative agreement with the U.S. EPA Office of Water.
The U.S. Geological Survey is planning to expand the work to a more comprehensive study, Kannan said.
Kannan also has documented high concentrations of tributyltins in stranded bottlenose dolphins on the Atlantic Coast.
Kannan published his work with MSU professor John Giesy, an internationally acclaimed environmental toxicologist who has widely documented the effects of environmental toxins on wildlife - especially aquatic birds - and serves as a national adviser on the issue.
###
RSS