INNSBRUCK - The Alps, seen as a pristine ecosystem, act as a magnet for toxic pollutants drawn from the atmosphere, a new international study shows.

In the icy lakes above the tree line, fish are contaminated with DDT from the tropics where the insecticide is used extensively against malaria. "We found that fish in the most contaminated lakes have 1,000 times more DDT than lower-lying lakes," Roland Psenner, a professor from Innsbruck University, told Reuters.

Together with other scientists, Psenner is preparing to publish the results of a European Union study into fish living in lakes around freezing point between Spain and Norway.

Psenner, a limnologist or fresh water expert, said the sub-zero temperatures around the Alpine peaks caused DDT, which evaporates over Africa or India, to humidify and fall as precipitation in a process known as "global distillation".

"It circles around the earth where it is warm and gets trapped over cold regions," he said.

"We knew about DDT at the poles, but not that it is also common in the Pyrenees and here in the Alps."

DDT is a synthetic insecticide that acts as a contact poison against a wide variety of bugs. Its use has been prohibited in Europe for more than 15 years because of its toxic effects on animals as it accumulates in the food chain.

FISH SHOW STRESS IN HIGH-ALTITUDE LAKES

In Austria, researchers have concentrated on a trio of tiny lakes in a nature reserve at an altitude of 2,400 metres (7,874 feet).

About 30 km (19 miles) from the Tyrolean capital Innsbruck, and accessible only by ski-lift, the chilly waters have polar-like temperatures. "These lakes are covered with ice for eight to nine months," Psenner said.

Because of their altitude, the lakes have no natural fish population. Habsburg Emperor Maximillian I, a keen hunter, is believed to have introduced the red speckled "Danube trout" to the Gossenkoelle Lake around 1500.

Despite their isolation from agriculture or heavy industry, the fish show stress symptoms due to a high accumulation of persistent organic pollutants known as POPs, Psenner said.

Contamination is below levels considered by the EU as damaging to human health, and the trout are seldom eaten. Psenner said that the amount of DDT found in the lakes posed no danger to drinking water.

However, the hormone-like effects of some POPs, including DDT, are still being investigated. These "endocrine disrupters" interfere with the hormone level of animals, apparently affecting their sexual organs.

Psenner said new statistics published in the British medical journal "The Lancet" last December supported the long suspected link between DDT and cancer.

ALPS REMOTE, NOT PRISTINE

Scientists have not yet studied the effect of airborne toxic pollutants on other Alpine wildlife such as chamois, marmots, rabbits and ermine.

"We have always said we have pristine ecosystems...in the meantime we have gone to saying ‘remote but not pristine," Psenner said. He said the slightest changes in temperature made a difference to whether POPs get trapped over the world’s freezing zones as they change their state between solid, liquid and gas.

"The substances go up into the air, come down with precipitation, and hop on further until they get caught in a cold trap," said Psenner who described the sequence as the "grasshopper effect".

With an annual average air temperature of zero degrees around Gossenkoelle Lake, POPs rarely regain their gaseous state and lift off for another journey around the earth.

"The colder it is, the more these substances accumulate," Psenner said.

He said a planned worldwide ban on toxic pollutants known as the "dirty dozen", including DDT, would clean up Alpine ecosystems but had met with opposition from leading scientists who say the move could result in millions of deaths from malaria in developing countries.

"It is not unethical to want to protect our ecosystem," Psenner said. "It is unethical that Third World countries have not been offered anything better than DDT for 50 years."

 Story by Karin Taylor
REUTERS NEWS SERVICE