A new study of wildlife in the exclusion zone around the ruined Chernobyl nuclear power plant in Ukraine has contradicted earlier reports that animals were thriving there.
After a three-year study of animal numbers in the zone, American and French researchers have concluded that radiation from the nuclear disaster in 1986 is still having a negative effect.
Reporting their findings in the journal Ecological Indicators, the BBC reports, the research team says that their census of species in the zone provides more evidence that contamination has a "significant impact" on biodiversity.
Between 2006 and 2009 the team counted and examined wildlife - insects, amphibians, reptiles, birds and mammals - and compared the abundance of species in the exclusion zone with similar types of habitats in the area, which were not contaminated.
"The truth is that these radiation contamination effects were so large as to be overwhelming," Professor Timothy Mousseau of the University of South Carolina says.
Professor Mousseau says the effects are particularly obvious in birds. Barn swallows, for instance, were observed to have tumours on their feet and necks and around their eyes.
'Haven for wildlife' claims rejected
Scientists in the Ukraine criticised the conclusions: they have previously argued that the area is becoming a haven for wildlife because of the absence of human interference.
But Professor Mousseau says such evidence is "purely anecdotal".
"This is the first paper that provides quantitative, rigorous data that the mammals really are significantly affected by contamination," he says.
"That said, it's not a bad idea to set this place up as a wildlife haven - it's a natural laboratory where we can study the long-term consequences of this kind of an accident."