Problemet med radioaktivt nedfald er, at kræft kan dukke op langt tid efter – i snit 28,7 år efter eksponering (indtagelse eller indhalering) af de [[radioaktive stoffer]].
<ref>[http://www.sciencedaily.com/releases/2009/04/090420170758.htm JAMA and Archives Journals (2009, April 24). Radiation Exposure Associated With More Aggressive Thyroid Cancer, Worse Outcomes. ScienceDaily] Citat: "...The average age at first exposure to radiation was 19.4 years, and cancers were diagnosed an average of 28.7 years later..."</ref>
Der er flere grunde til at dyr tilsyneladende ikke ser ud til at være påvirket af radioaktiviteten. En er at dyrs livslængde er meget kortere end menneskers. En anden er at ungdyr som måtte være skadet af radioaktivitet f.eks. pga. [[mutation]]er hurtigt går til, da rovdyr har lettere ved at fange dem.
<ref>[http://news.nationalgeographic.com/news/2006/04/0426_060426_chernobyl.html April 26, 2006, nationalgeographic.com: Despite Mutations, Chernobyl Wildlife Is Thriving] Citat: "...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...Working in the Red Forest area, James Morris, a USC biologist, has observed some trees with very strange twisted shapes..."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."..."</ref>
Samfund Fysik Kemi Teknologi