Scientists divided over Chernobyl ecosystem

When top predators such as wolves and eagles return to a damaged habitat, it is a sure sign that the ecosystem is once again healthy and vibrant.

For several years, ecologists have reported many sightings of rare species within the Chernobyl exclusion zone which are hardly ever seen in other parts of Europe.

Robert Baker, a biologist at Texas Tech University who has made more than a dozen scientific excursions into the zone, said the diversity of wildlife around the stricken plant was what might be expected in a nature park dedicated to conservation.

"The benefit of excluding humans from this highly contaminated ecosystem appears to outweigh significantly any negative cost associated with Chernobyl radiation," Dr Baker said.

In a comprehensive assessment of the damage caused by the Chernobyl accident, the British ecologists Jim Smith and Nick Beresford point out that radiation levels considered potentially dangerous to humans have little if any effect on wildlife.

"Nearly 20 years after the accident there is some (often contradictory) evidence of continuing radiation damage to organisms, but this appears to be relatively minor (although poorly understood)," they say in their book, Chernobyl - Catastrophe and Consequences.

"Radiation is considered to be a risk to humans when there is a small, but significant, probability of cancer induction in later life. Though cancer induction in animals is possible, a small additional cancer risk does not affect wild populations as a whole. Animals in the wild are less prone to cancer than human populations. They are most likely to be killed by natural predators or starvation before they reach an age at which cancer risk increases," they say.

Not all scientists accept this assessment.

Anders Moller and Timothy Mousseau studied swallows in the exclusion zone and found they carry a significantly higher level of "germline" mutations in their sperm and eggs compared to swallows elsewhere.

"Our work indicates that the worst is yet to come in the human population.

The consequences for generations down the line could be greater than we've seen so far," said Dr Mousseau, a biology professor at the University of South Carolina.

- INDEPENDENT