This article was originally posted on RealClearScience.
When people think of radioactivity, many imagine it converting cute, fluffy animals into scary, green, glowing mutants. But, that’s just a myth. Radioactivity is invisible. The reason we associate radiation with “glowing green” is because many types of instrument dials (such as a clock face) were painted with radioluminescent paint, a mixture that contained a radioactive isotope (often radium) and other chemicals that would emit green light in response to the radiation. Similarly, while it is true that some nuclear power plants produce a hauntingly blue glow, this is not because the radioactive fuel itself is glowing, but because of a strange phenomenon known as Cherenkov radiation, in which particles moving faster than the speed of light emit photons, generally in the UV to blue light range.
However, this is not the whole story. The great radiation/color narrative has taken yet another twist. A team of scientists led by Zbyszek Boratyński has reported in the journal Scientific Reports that Chernobyl radiation has changed the hair color of local rodents.
To determine this, the team captured bank voles in the vicinity of the Chernobyl nuclear plant and measured the nearby soil radiation. Digital photographs were taken of the fur on the animals’ backs, and the amount of red color was assessed. The authors found that voles exposed to greater levels of radiation had less red pigmentation. (See graph.)
Why this should be the case is not perfectly clear, but the authors propose an intriguing explanation. The production of red pigment (pheomelanin) requires the consumption of antioxidants. Protection of the body from free radicals, which are generated by radiation, also requires the consumption of antioxidants. So, the authors hypothesize that the rodents synthesize less red pigment in order to save antioxidants for a far more crucial purpose.
There is still much work to be done.
First, the correlation coefficient (r = -0.15) is rather weak. This implies that only about 2% of the observed variation in fur color is explainable by the radiation. (The authors did, however, use an alternate method on a sub-sample which showed a greater correlation.) Repeating the experiment with a larger sample may be necessary.
Second, the ecological significance is unknown. It is possible that voles with differently colored fur are more/less susceptible to predation, or it could be that slight changes in fur coloration have no effect whatsoever. The authors plan to investigate this further.
Finally, the proposed molecular mechanism needs to be verified.
Still, regardless of the outcome of their subsequent investigations, the authors appear to have gained an interesting insight on how animal life has learned to adapt to the less-than-ideal conditions at the Chernobyl disaster site.
Source: Zbyszek Boratyński et al. “Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus).” Scientific Reports 4: 7141. Published: 21-November-2014. doi:10.1038/srep07141