Radiation has affected animals living near the site of Ukraine's Chernobyl nuclear disaster far worse than was previously thought, a study out this week shows, challenging beliefs that wildlife was recovering.
The study, published in the latest Royal Society Biology Letters, presents the most extensive data set ever compiled on the abundance of animals at and around the Chernobyl site. "Abundance" is relative in this case, however, since scientists Anders Moller and Timothy Mousseau determined that insect, bird and other animal populations have dramatically diminished there in the two decades following the disaster. "Chronic, continuous exposure to low dose radiation appears to be the cause," Mousseau, director of the Chernobyl Research Initiative at the University of South Carolina, said. For three years, he and Moller conducted population censuses on invertebrates at more than 700 sites near Chernobyl. At each site the researchers measured radiation levels, using Geiger counters and aerial scan data. They also counted numbers of bumblebees, butterflies, grasshoppers, dragonflies and spider webs.
The research reveals that numbers of bumblebees, butterflies, spiders, grasshoppers and other invertebrates were lower in contaminated sites than other areas because of high levels of radiation left over from the blast in April 1986.
This challenges earlier research that suggested animal populations were rebounding around the site of the Chernobyl explosion, which forced thousands of people to abandon their homes and evacuate the area.
Estimates of the number of deaths directly related to the accident vary. The World Health Organisation estimates the figure at 9,000 while the environmental group Greenpeace predicts an eventual death toll of 93,000.
A team from the National Centre for Scientific Research in France compared animal populations in radioactive areas with less contaminated plots and found some were nearly completely depleted of animal life. "We were amazed to see that there had been no studies on this subject," Anders Moller, a researcher at the National Centre for Scientific Research in France. "Ours was the first study to focus on the abundance of animal populations." "Usually (deformed) animals get eaten quickly, as it's hard to escape if your wings are not the same length," Moller said. "In this case we found a high incidence of deformed animals." "We wanted to ask the question: Are there more or fewer animals in the contaminated areas? Clearly there were fewer," said Moller, who has worked on Chernobyl since 1991.
The researchers also found that animals living near the reactor had more deformities, including discolouration and stunted limbs, than normal.
Mousseau and Moller have since identified high mutations in many different species of birds, plants and animals, including humans. Children living near the plant continue to be monitored, as many suffered from thyroid cancer right after the nuclear blast. More recent tests "show significant negative impacts" on the blood cell counts of local children. "The truth is that accidents do happen, so there likely will be a future nuclear accident somewhere," Mousseau warned. "We also face the threat of nuclear terrorism, so I'm hopeful our studies can shed light on the long-term consequences of radiation exposure."
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