|Fig. 1: Selected risks from radiation sickness. (Source: Wikimedia Commons)|
The debate over whether nuclear power's benefits are worth the possible threat posed by a faulty reactor or nuclear spill has been an ongoing controversy ever since modern adoption nuclear power. Today the fear of radiation remains prevalent within society. But few have a complete understanding of the actual danger posed by radiation, or what enables radiation to have such a toxic effect on the body.
A high level of radiation exposure, such as received by people at Chernobyl or the atomic bombings of World War II, kills immediately.  Radiation's toxic effects manifest in radiation sickness, where there is intense damage to internal organs, intense vomiting, internal bleeding, and decimation of white blood cells, as shown in Fig. 1. Those who die in the following years from radiation exposure are often taken by cancer, especially one of the organs.  On the cellular level, this cancer's roots can be, and have been in studies, traced back to radiation exposure.  It is shown that radiation-induced ionizations causes the creation of water-derived radicals which oxidize surrounding molecules, ultimately resulting in DNA breaks.  These breaks, especially the double stranded ones, result in faulty DNA replication which causes mutations with the possibility of eventually resulting in cancer.  Different types of radioactive substances have different effects. For example, radioactive iodine only stays in an environment for about a week, but is preferentially absorbed by the thyroid and often seen as the root of the increased rates of thyroid cancer observed in those who have been exposed to large amounts.  Alternately, radioactive cesium stays in an environment for much longer, due to it being incorporated into the surrounding plant life through roots, and is thought to lead to longer term harm.  Through studies of survivors of Chernobyl, it is estimated that children who were exposed to the highest amount of radiation (through consuming milk that contained radioactive iodine) were at 6 times more risk for thyroid cancer. 
Radiation is being constantly emitted at low levels all around us.  But it is when these levels spike that the potential for damage arises. Things like the sun, the ground, and even bananas (due to their K-40 content) are constantly emitting radiation, but in most cases in amounts too small to adversely affect us.  For now, Americans can rest easy, as we are on average only exposed to 27-35 mGy (milligray) per year.  Half of this amount occurs naturally, and the other half is from sources we have created, such as medical procedures, or residue from nuclear testing.  Furthermore, blanket conclusions about what amount of radiation exposure will cause harm are troublesome. This is because a concentrated dose, like those used in cancer treatment, has a different effect than a dose received by someone after a nuclear spill. For example, 20-60 Gy delivered to site of tumor, will not result in death, while if the whole body received this dose death would be certain. 
The current fear surrounding radiation, while well founded, is also often ill-informed. Radiation is harmful to the body, but not in the amount that an average American is currently exposed to. While radiation interferes with the crucial process of DNA replication, and repair, the body is extremely resilient and must be exposed to high levels to even seen slight increased likelihoods of cancer among that population.  As it stands there are no data suggesting that the current average exposures to radiation are sufficient to harm the average person. It is hard to quantify the dangers of radiation, as it is difficult to attribute long term effects to solely radiation exposure, and experimental studies exposing humans to high levels radiation cannot be performed due to the harm it would cause to subject. 
© Olivia Hallisey. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 Sources and Effects of Ionizing Radiation (United Nations, 2000).
 K. B. Moysich, R. J. Menenzes, and A. M. Michalek, "Chernobyl-Related Ionising Radiation Exposure and Cancer Risk: An Epidemiological Review," Lancet Oncol. 3, 269 (2002).
 N. S. Fisher et al., "Evaluation of Radiation Doses and Associated Risk from the Fukushima Nuclear Accident to Marine Biota and Human Consumers of Seafood," Proc. Nat. Acad. Sci. (USA) 110, 10670 (2013).
 E. P. Rogakou et al., "DNA Double-Stranded Breaks Induce Histone H2AX Phosphorylation on Serine 139," J. Biol. Chem. 273, 5858 (1998).
 V. Miller, "Natural and Medical Radiation Dosages," Physics 241, Stanford University, Winter 2012.