We are also worried about the health & safety of the workers and nearby residents who have been evacuated. Our hearts and thoughts are with them.
Herein, I give a little background to address some other worries that we may have as molecular ecologists: what are the effects of the radioactivity on the wildlife in the short-term and long-term? Will these releases increase genetic load & lead to future ‘mutational meltdowns?’
I have spent much of the past 15 years studying the effects of radioactivity on wildlife, especially the long-term genetic effects due to low doses. I had the great fortune to work for nearly a decade at the University of Georgia’s Savannah River Ecology Lab (SREL), which is located on the U.S. Department of Energy’s Savannah River Site. This 310 square mile site is home to five retired nuclear reactors that produced nuclear materials for US weapons which have produced some minor releases of radioactivity into the environment (some of which persists nearly 50 years later). As part of my work at SREL, I had the opportunity to conduct research at Chornobyl in collaboration with researchers at the International Radioecology Laboratory. Thus, I have some familiarity with this particular subject.
Below I briefly summarize some major points about radioactivity in the environment, stressing information from Chornobyl, (lead authors of some key publications are noted):
- The initial release of radioactivity at Chornobyl was tremendous, probably the most or second most from any human activity. This certainly caused immediate negative consequences, to humans, plants and animals. The “red forest” got its name because it was defoliated in spring-time due to the radioactivity. It is quite unlikely that Japan will see a release anywhere close to the amount released from Chornobyl reactor #4.
- Most classic information about the amount of radioactivity released into the environment & the effects of radioactivity on animals, the environment, etc. exists in “gray literature”; i.e., government sponsored documents produced in the U.S., Soviet Union, etc. in the 1950′s and 1960′s. Classic work deducing mutation rates caused by radiation using phenotypically expressed mutations was done by William Russell et al. Radioactive contamination is generally distributed log-normally among individuals in wild populations (i.e., only a few individuals get very high doses; Mike Smith, Taras Oleksyk et al.).
- There is clear and convincing experimental evidence that even small amounts of radiation can cause increased mutation rates at microsatellite loci (Olga Tsyusko et al.) and ESTRs (Yuri Dubrova, Ruth Barber, et al.); (see also work by Chris Somers et al. on air pollution; Carol Yauk et al on single sperm assays; Dubrova, Somers, and Yauk have each written excellent reviews)
- One can reasonably conclude that Chornobyl releases caused increased mutation rates at microsatellite loci in birds (Hans Ellegren et al.), plants (Olga Kovalchuk et al.), and minisatellites of humans (Dubrova & Alec Jeffreys); although all of these have been criticized (not always fairly) by others.
- There are few studies that have found convincing phenotypes associated with radiation exposure (but, see Ellegren et al. for a classic exception).
- A significant knowledge gap exists concerning the health/fitness effects associated with slight elevations in mutation rates detected at microsatellites, ESTRs, or minisatellites (Tom Hinton et al.); recent low-dose RFPs also address the lack of knowledge about what genes are stimulated by low-dose exposure
- A strikingly clear effect is that with human activities dramatically reduced in the Chornobyl exclusion zone, wildlife is much more abundant than it was previously (Ron Chesser, Robert Baker, et al.)
- Several relatively recent studies argue for a variety of subtle long-term ecological effects due to radioactive releases at Chornobyl (Tim Mousseau, Anders Møller, et al.)
- A few studies suggest that low-doses of radiation can be beneficial (i.e., hormesis; or hormetic effect), and studies on priming doses suggest that a modest initial dose of radiation can ameliorate some effects from subsequent high doses (e.g., within 24 hours).
So, what does all that mean?
First, even after decades of study by large numbers of scientists around the globe, making radioactivity one of the best studied environmental contaminants, significant knowledge gaps remain. Second, even large releases of radiation aren’t likely to cause massive die-offs in the short term. Finally, it is reasonable to be concerned about long-term effects from radiation and the very large number of other environmental contaminants that may induce mutations and transgenerational epigenetic modifications. However, significant amounts of research are needed to understand these threats to future humans and the organisms with whom we share the planet.
Posted on the blog The Molecular Ecologist
-Dr. Travis Glenn
Posted March 16, 2011.