Radiation and three-eyed fish

Radiation is energy moving in the form of waves, or particles – and is generally thought of as being either ionizing, or non-ionizing. The difference between these two types of radiation is that ionizing radiation has enough energy to actually knock electrons off an atomic element, such as hydrogen, or copper – it is this process which is called ionization. The energy from this type of radiation is so powerful that it may cause a chain reaction of electrons from atom to atom, one after the other, colliding and being ejected, until it dissipates, or passes through the object it has encountered.

Imagine picking up an apple which has fallen from an apple tree and throwing it very hard – aiming at the tree and one of the other apples hanging on a branch. If you manage to hit the other apple with enough force it may be knocked loose from it’s branch, perhaps hitting another apple afterwards and knocking it loose too. Your original apple, as well, may continue to knock other apples from the tree if it was thrown hard enough. In this example, of course, our thrown apple represents radiation – and the apples on the tree are individual electrons bonded to an atomic nucleus.

What is the effect of this kicking-about of electrons? When high-energy radiation causes ionization, it can result in the deterioration of chemical links between atoms and molecules, destroying the structure of cells or damaging the DNA to alter the functioning of the cell. The human body has mechanisms to rid itself of cells which are malfunctioning or dead as well as the ability to heal lesions or wounds as a result of cells being destroyed. However, in some cases, ionizing radiation can trigger a cell to be cancerous: these cells do not activate the body’s mechanism to remove malfunctioning cells and grow rapidly, destroying other cells nearby and possibly spreading to other parts of the body.

There is no disagreement about the fact that nuclear power facilities are sources of ionizing radiation, however, the nuclear fuel, the source of this radiation is heavily shielded from plant workers and the environment. Nuclear power plants are required to check for radioactivity in the air, soil and water near where they are located. Under normal operating conditions very little ionizing radiation is found in the locale of nuclear power plants.

While most of us know that intense radiation causes cancer what may remain unclear is how much radiation is too much? Firstly, the environment in which we live is naturally radioactive: radiation arrives from outer space, occurs in natural gasses, food and the earth itself. This isn’t to imply that radiation is inherently safe – there are limits to what is expected as normal exposure to radiation. On average, the dose of radiation we receive yearly is less than 4 sieverts (4 Sv). If you were to be exposed to a source of powerful ionizing radiation you could possibly receive 4 Sv in seconds, or minutes. Up to 1 Sv may cause headaches and increased risks of disease due to temporary incapacity of the human immune system. 4 Sv is likely to result in death in 50% of those exposed. Between 6 – 10 Sv is normally fatal within 14 days of exposure.

Returning to the fictional concept of Blinky the three-eyed fish we must conclude that while ionizing radiation will produce a range of effects, including fatalities in organisms exposed to high doses, this level of radiation is not normally present near nuclear power plants. As well, if a living animal had been in the presence of ionizing radiation it would not be possible for multiple cells in it’s body to be mutated in the same manner to result not only in healthy functioning cells – but as well, to be transformed into the different types of cells and structures required to form a new organ. (eg. In the case of an eye, retina cells, pupil cells etc.)

However, while changes to a cell in an already living animal will not spontaneously produce new limbs and such, we know that mutations in DNA do occur during sexual reproduction. Can ionizing radiation alter DNA in a parent which is then passed down to a child – and result in meaningful, usable structures such as limbs and eyes? It appears that the research on this topic indicates that in instances of both low and high levels of ionizing radiation no increase in genetic affects has been noted. It must, however, be made clear that individuals exposed to high concentrations I-131 (a form of radioactive iodine) which has found its way into the atmosphere as a result of the detonation of nuclear weapons – and due to catastrophic accidents such as the 1986 Chernobyl explosion – have a much higher risk of thyroid cancer than is found in the regular population.

While this article has begun with a somewhat light-hearted approach - asking about the possibility of creatures such as Blinky the fish - we must take very seriously the risks associated with the generation of power through nuclear fission. And we should remain concerned and continue research on the safety of nuclear generating stations during their operation and the storage of the depleted yet still radioactive fuel rods after they are no longer useful.

For more information

OECD - Nuclear Energy Agency 2002 Update on Chernobyl
http://www.nea.fr/html/rp/chernobyl/c01.html

US Environmental Protection Agency - Calculate your yearly radiation dose
*note - this form measures radiation dose in 'mrem' (100 mrem = 1 sievert) (Sv)
http://www.epa.gov/radiation/students/calculate.html

COMARE - Committee on Medical Aspects of Radiation in the Environment
http://www.comare.org.uk/