pesticides poison whales, marine wildlife

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NewsTarget: pesticides poison whales, marine wildlife

Wed, 28 Dec 2005 08:39:12 -0700

 

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Bringing you the inside story on topics that matter

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Although we're still on an abbreviated schedule this week, today we

bring you an article about the use of TBT poisons (pesticides) in the

shipping industry.

 

These toxic chemicals are wiping out ocean wildlife and harming seals,

dolphins and whales. The chemical even causes some whales to go

partially deaf, making ocean navigation virtually impossible. (Ever

wonder why so many whales are beached these days?)

 

So why does the U.S. still allow these chemicals to be used?

 

 

 

 

Full story at:

http://www.newstarget.com/016127.html

 

 

http://www.newstarget.com/016127.html

 

Originally published December 27 2005

 

Toxic pesticide TBT poisons worldwide marine wildlife; used widely on

hulls of oil tankers

 

There is something picturesque about a ship bobbing up and down

against a blue swell of waves and settling into a harbor to unload its

cargo. Equally picturesque are the kinds of wildlife navigating

underneath: Fish and shellfish scurrying about the colorful blooms of

coral, piles of oysters and larger mammals, like whales and dolphins,

swimming to and fro. This picture of the oceanic ecosystem is serene,

almost quiet. Unfortunately, the reality of our modern marine

ecosystem is far different.

 

For 40 years, oceanographers and fishermen have warned governments of

certain marine technologies destroying the vast biota underwater. In

the most recent case of environmental destruction, the culprit comes

in the form of strong chemicals painted on the hulls of ships to

protect from pests. Tributyltin oxide (TBT), an organotin compound, is

the active ingredient in these marine paints. TBT prevents the growth

of algae, barnacles and other marine organisms on the ship's hull,

but, like most pesticides, these chemicals kill much more than just

their targets.

 

TBT was first used in the 1960s as an antifouling biocide, but signs

of its destructive properties didn't emerge until the 1970s. In both

Europe and the United States, studies began to show rapid decimation

of marine life in harbors and other high-traffic areas. The American

mud-snails, dogwhelks, oysters and other mollusk populations were all

in decline by the early 1970s. Shellfish were found suffering from

impaired immune systems, shell deformities and a condition called

imposex, in which male sexual organs appear on female mollusks.

 

Unfortunately, the link between these conditions and TBT was not

immediately apparent. Only in the 1980s, using advanced analytical and

technological instrumentation to measure TBT distribution, could

scientists link these deformities directly to TBT levels. In 1986, one

study of Plymouth Sound proved that increases of imposex strongly

coincided with TBT applications. In 1989, studies found that the use

of TBT paints on salmon-farming cages resulted in contamination of a

Scottish sea loch, as well as higher incidence of imposex.

 

As the evidence mounted against TBT, governments slowly began to

establish regulations. France, suffering huge losses in the oyster

industry, was the first country to limit the use of TBT. In 1982, the

French government placed controls on the application of TBT paints to

vessels under 25 meters in length. (These small vessels usually spend

most of their time around harbors where oyster populations could be

severely effected). In 1987, the UK went one step further, banning all

retail sale of TBT paint for smaller vessels. As usual, the United

States was slowest to take action, introducing a similar ban in 1988.

 

Unfortunately, these restrictions and bans did not take into account

sea-going vessels. While many of the shellfish populations partially

recovered in harbors and bays, TBT dangers were by no means

eliminated. The increase in commercial vessels, especially oil tankers

and military vessels (both using unregulated amounts of TBT paint),

has had measurable effects on marine ecosystems.

 

During the mid-1990s, a number of studies introduced new harms caused

by TBT. This time, the effects of TBT were not limited to smaller

marine life in harbors. Scientists found dangerous accumulations of

butyltin in dolphins, tuna and sharks in the Mediterranean seas. A

later study linked these levels to immune dysfunction. In 1997, a

study linked high levels of TBT in the bottlenose dolphin to their

abnormal rates of mortality reported on the U.S. Atlantic and Gulf

coasts. Greenpeace also reported that TBT was been found in the

tissues of cetaceans, seals, sea otters and water birds in a wide

range of locations around the world.

 

Most startling, however, is evidence that dangerous amounts of TBT and

its breakdown products accumulate in the bodies of sperm whales. This

indicates that TBT may be widely dispersed in the marine environment,

including the deep oceans where sperm whales normally live and feed.

 

In a recent study at Yale University, researchers found that TBT could

cause hearing difficulties in whales and other mammals. Prestin, a

protein essential to whale cochlear amplification (the amplification

of sounds by tiny hairs) is severely affected by TBT levels. By

hindering the mechanical activity of the outer hair cells, which boost

incoming sound to the whales, TBT effectively cripples whales'

auditory amplification and sensation. Because whales rely on their

sensitive hearing apparatus for motor activity, damage to their ears

could alter, if not annihilate, populations in some areas.

 

Current efforts are under way by Greenpeace and other marine

environmental groups to push the government to restrict TBT use even

further, if not outlaw the pesticide outright. Until then, marine

populations will continue to be threatened by these toxic pesticides

that remain perfectly legal to use on the hulls of oil tankers and

other ships that traverse the oceans of our planet.