Despite Mutations, Chernobyl Wildlife Is Thriving

[Sally Furniss]

Despite Mutations, Chernobyl Wildlife Is Thriving

Kate Ravilious
for National Geographic News

April 26, 2006
<!--- startbody --> Twenty years ago today, reactor number four at the Chernobyl Nuclear Power Plant exploded. The blast covered vast areas of Belarus, Ukraine, and Russia (see map) with dangerous radioactive material.

The effects of the Chernobyl catastrophe are still being felt today—whole towns lie abandoned, and cancer rates in people living close to the affected areas are abnormally high.

But it turns out that the radioactive cloud may have a silver lining. Recent studies suggest that the 19-mile (30-kilometer) "exclusion zone" set up around the reactor has turned into a wildlife haven.

Roe deer bounce though the deserted houses while bats roost in the rafters (related photos: inside today's Chernobyl).

Plants and trees have sprung back to life, and rare species, such as lynx, Przewalski's horses, and eagle owls, are thriving where most humans fear to tread.




From Red to Green

The situation is a far cry from the way things looked just after the accident. Initially many animals died from the huge doses of radiation they received.

The red color of withered pine needles earned one large area near the reactor the name Red Forest.

"Now it is not the Red Forest but a real green forest, due to [growing] birch trees," said Sergey Gaschak from the International Radioecology Laboratory in Kiev, Ukraine.

And in the towns where humans have moved out, plants and animals seem to have moved in.

"Wild boar like to live in former villages, and I have found many birds' nests in the buildings," Gaschak said.

Even the site of the explosion seems to be bursting with life.

"I met a hare in the sarcophagus area, and birds nest there," said Gaschak, referring to the concrete and steel shell that encases the still smoldering reactor. But while wildlife seems to be proliferating in the Chernobyl exclusion zone, not everyone is convinced that these plants and animals are healthy.

Anders Moller from the University of Pierre et Marie Curie in Paris, France, and Tim Mousseau from the University of South Carolina (USC) in Columbia have been studying Chernobyl's bird populations. Mousseau is a National Geographic Society grantee. (National Geographic News is part of the National Geographic Society.)

Moller and Mousseau have shown that certain species in the area have a higher rate of genetic abnormalities than normal.

"We find an elevated frequency of partial albinism in barn swallows, meaning they have tufts of white feathers," Mousseau said.

Late last year Moller and Mousseau published a paper in the Journal of Animal Ecology showing that reproductive rates and annual survival rates are much lower in the Chernobyl birds than in control populations.

"In Italy around 40 percent of the barn swallows return each year, whereas the annual survival rate is 15 percent or less for Chernobyl," Mousseau said.

Moller and Mousseau think that migratory species, such as the barn swallow, are particularly vulnerable to radioactive contaminants, because they arrive in the area exhausted and with depleted reserves of protective antioxidants due to their arduous journey.

The scientists are also concerned that the mutated birds will pass on their abnormal genes to the global population.

"In the worst case scenario these genetic mutations will spread out, and the species as a whole may experience enhanced levels of mutation," Mousseau said.

"Great Irony"

Mutation isn't the only adverse effect of the radiation. Working in the Red Forest area, James Morris, a USC biologist, has observed some trees with very strange twisted shapes.

The radiation, he says, is confusing the hormone signal that the trees use to determine which direction to grow.

"These trees are having a terrible time knowing which way is up," Morris said.

Gaschak, the Kiev ecologist, believes such radiation effects will diminish over time. He is celebrating the way that Chernobyl has burst into life and hopes that the area will become a national park one day.

But Mousseau is less optimistic. "One of the great ironies of this particular tragedy is that many animals are doing considerably better than when the humans were there," he said.

"But it would be a mistake to conclude they are doing better than in a control area. We just don't know what is normal [for Chernobyl]. There just haven't been enough scientific studies done."

http://news.nationalgeographic.com/news/2006/04/0426_060426_chernobyl.html

[Giuseppe]

Re: Despite Mutations, Chernobyl Wildlife Is Thriving

Unfortunately, some of the radionuclides dispersed into the environment during fallout of Tchernobyl disaster in late '80 have centuries-long ''lifetime''.

The cumulative effects on DNA are at least unknown or difficult to evaluate without an extensive research onto field.

Further, the Tchernobyl Nuclear Power Plant - now closed - continues to smoldering an atomic core and urgent containment interventions should be pursued by international community in order to avoid the release of highly radioactive materials into atmosphere.

The actual extent of human and animal contamination continues to remain obscure.

[Sally Furniss]

Re: Despite Mutations, Chernobyl Wildlife Is Thriving

Chernobyl, 20 Years Later: ASCP Leader Heads Pathology Panel That Diagnoses Cancer Cases

Posted 01/09/2007
Ellen J. Sullivan
Author Information

Information from Industry

Twenty years after the world's worst nuclear accident, pathologists are studying the unusual morphology of papillary thyroid cancer tumors that have appeared in people who were children -- some even still in utero -- when they were exposed to radiation in and around Chernobyl, Ukraine.

Virginia A. LiVolsi, MD, FASCP, chair of the Pathology Panel of the Chernobyl Tissue Bank, made a presentation on "Specific Pathologic Findings in Thyroid Cancer After Radiation Exposure" on April 20, 2006, at conference called "Living With Radiation: Diagnosis and Treatment of Thyroid Cancer After the Chernobyl Nuclear Accident" held at the United Nations Headquarters in New York. She presented similar information at the "Chernobyl Thyroid Cancer Convocation: 20 Years After the Disaster" on May 1 in Boston.

Several factors make these cases unusual, said LiVolsi. For starters, the fact that these cancers first appeared in people who were children, not adults, when the disaster occurred is different. Even after the United States dropped atomic bombs on Hiroshima and Nagasaki in Japan in 1945, the first cases of thyroid cancer occurred in people who were adults when they were exposed.
"That's why this was so dramatic -- it was the kids," said LiVolsi. The tumors first started appearing in late 1989, early 1990 -- only 3 to 4 years after the accident, whereas in Japan, the first tumors arose around Year 9 or 10.
Second, the panel studied pathologic features of papillary thyroid tumors that developed in children from the radiation-affected areas and compared those with papillary thyroid tumors that developed in children in Japan and the United Kingdom.

"We looked at a variety of morphologic features and found that the tumors that arose after the Chernobyl accident seem to be more commonly of the solid subtype of papillary carcinoma than those that arose in Japan, almost all [of which]were classic usual papillary carcinoma," LiVolsi said. "The ones that arose in the UK were sort of a mixture. We tried to figure out what could be different except for the fact that the ones from the former Soviet Union countries were [in] kids who had been exposed to radiation."

What eventually turned up was the fact that in the former Soviet Union countries, there had been a severe iodide deficiency in the diet. The Japanese diet has one of the highest, if not the highest, iodide content in the world, and the UK diet falls in between. "And the pathology followed that," said LiVolsi. "So the suggestion was made in our paper, which was published in 2004, that the variation in the morphology might be related to dietary iodide, as opposed to just the radiation. So there might be other factors."

According to LiVolsi, there are not enough data yet to understand the difference between the solid and classical tumors. "What we do know -- and this is from a strictly morphologic point of view -- [is that] the solid variant tends to, under the microscope, look like a more aggressive tumor," she said. "There's more extension of the tumor beyond the confines of the thyroid itself -- what's called extrathyroidal extension. So that increases the stage of the lesion. And there is more vascular invasion in the solid variant. But up to now, it is not possible to say that that is associated with a greater mortality, because very few of the kids have died, fortunately. From a clinical point of view, we can't say yet [whether the tumor is more aggressive]."

For now, the existence of a relatively higher proportion of solid tumors is "just a very curious morphologic variance," said LiVolsi. "In terms of clinical aggressiveness, it's really difficult right now to have enough data. I think in another 10 years, follow-up on the post-Chernobyl children may give us some handle on what we're dealing with here."

The panel has made available DNA and RNA extractions as well as tissue microarrays of samples from the tissue bank for scientists in the international community to conduct molecular studies on the material. What they are finding is that about 60&#37; to 70% of papillary thyroid cancers are associated with RET (a proto-oncogene) rearrangement or translocations, said LiVolsi.

"The sporadic adult papillary thyroid cancer (PTC) tends to show rearrangements in what's called RET/PTC1," she said. "In the children of Chernobyl, especially those children who have the solid subtype of papillary carcinoma, the translocation appears to be in RET/PTC3. So, there's something a little bit different."

Mutations in BRAF (the gene for the B-type Raf kinase) are another new molecular marker in adult papillary carcinoma. "Again, depending on the laboratory and the population studied, approximately 45% of sporadic adult papillary carcinomas have that mutation," she said. "Now a number of laboratories have looked at the Chernobyl thyroid cancers in the kids, or the exposed kids, and the incidence of BRAF mutation in those children is far less than 10%. And, in fact, none of the tumors that are solid variant have BRAF mutation. As of today, we have not found that."

The Pathology Panel has submitted an abstract of the data on the BRAF mutation findings to the European Thyroid Association meeting, for presentation at the association's September 2006 meeting.

The panel, which first convened in 1998, is comprised of representatives from Ukraine, Russia, Europe, Japan, and the United States. It meets once every 6 to 8 months and reviews the representative slides of tumors that have occurred and been operated on in Ukraine and Russia since the previous meeting. "We've probably looked at somewhere over 2000 cases," said LiVolsi. "I think the estimate is that there have been approximately 4000 cancers, but we haven't seen all of them."

LiVolsi stressed that all tumors are obtained from patients who give their informed consent, that samples are only provided to researchers who submit scientifically valid and approved proposals, and that all tumors are handled according to agreed-upon standard operating procedures, which include the process of extracting DNA and RNA.

The main job of the Pathology Panel, said LiVolsi, is the "diagnosis, confirmation of diagnosis, and agreed diagnosis -- a consensus diagnosis by an international group of pathologists who concentrate in thyroid, so that the international research community can . . . try to figure out what, if anything, we can learn from this tragic experience . . . and hopefully something of this kind will never happen again."

http://www.medscape.com/viewarticle/544071