Why does it make no sense to compare in-flight radiation exposure and ingesting radioactive isotopes? It is wrong to compare internal emitters with external emitters (i.e, ingesting radioactive isotopes versus in-flight exposure or background radiation). It is like comparing warming oneself near a fire versus eating a red hot coal. Physicians for Social Responsibility in the United States recently issued a statement asserting “there is no safe level of radionuclide exposure, whether from food, water or other sources. Period.” There are a number of different types of radiation, including cosmic radiation from space, terrestrial radiation which is emitted by radioactive elements in the ground, and man-made radiation such as that released by the detonation of an atomic bomb or by nuclear reactors in meltdown.
Further to the ATCA briefing, “San Francisco Rainwater: Radiation 181 Times Above US Drinking Water Standard” many have pointed out that the University of California at Berkeley “Rainwater Sampling” chart shows even at the peak finding of 20.1 Becquerels per litre, someone would have to consume 134 litres of that water in order to have the same exposure to radiation as they would receive by taking a flight from San Francisco to Washington, DC.
With respect, we consider this comparison to be utterly misleading. Why? If living beings are exposed to radioactivity indirectly versus if they ingest something radioactive, the total effect is remarkably different. Radiation and contamination are not the same thing. Taking a flight will expose one to cosmic radiation not radioactive contamination. When radioactive isotopes enter into water, crops, milk that leads to radioactive contamination. Contamination occurs when material that contains radioactive isotopes is no longer contained. It is important to remember that radiation cannot spread or get “in” or “on” people; rather it is radioactive contamination that can do precisely that. Here lies the essential difference between the two.
It is important to note that exposure to radiation — like standing in front of a microwave oven where the seal has been damaged or an X-Ray machine — does not result in direct contamination of any living being, because they become contaminated only through direct contact with radioactive isotopes or by being in areas where the contaminated material is already present.
Radioactive contamination and radiation exposure occur only if radioactive materials are released into the environment as the direct result of a nuclear accident, an event in nature — such as ground radiation with radioactive isotopes — or an act of war involving nuclear devices or radioactive isotopes. Such a release may expose living beings and contaminate their surroundings and their environment.
Radioactive contamination occurs when radioactive material is deposited on or in an object or a living being. Radioactive materials released into the environment can cause air, water, surfaces, soil, plants, buildings, people or animals to become contaminated. A contaminated living being has radioactive materials on or inside their body.
If humans ingest radioactive elements, those “hot coals” stay with us. Particularly nasty radioactive elements include radioactive iodine. Radioactive iodine is also readily absorbed by the body and becomes incorporated within it, and is therefore difficult to eliminate from the body. The radiation it emits can cause cancer over a period of time.
Fast moving photons (gamma rays), electrons (beta rays) and helium nuclei (alpha particles) can crash into other molecules and change their structure. Beta particles may ionise molecules they hit, damaging DNA in cells, and disrupting their normal activities. If this happens to a DNA molecule, the damage is caused to the genetic information, and this may turn the cell cancerous.
Ionising radiation has the power to break molecular bonds in living tissue causing damage, even in small doses, it can cause cancer in humans and other living beings. If a lot of radioisotopes are ingested, the result would be radiation sickness and possibly death.
Properties of Radioisotopes
Chemical properties of radioisotopes are extremely important when determining the effect that a specific radioisotope will cause. Chemical properties determine the rates of absorption, rates of metabolism and even where the isotope will be deposited.
Radiation exposure potential is also determined by the type of emission from the radionuclide. Emissions that are not very penetrating while not externally a hazard become a very serious hazard when incorporated into the living body. Alpha and beta radiation will not penetrate even a few layers of skin; however, if a radioisotope that emits alpha or beta radiation is absorbed into the body and deposited in or near radio-sensitive cells, alpha or beta particles do not have to travel very far to damage the body’s cells permanently.
A living being exposed to radiation is not necessarily contaminated with radioactive material. A living being who has been exposed to radiation has had radioactive waves or particles penetrate the body, like having an X-ray or going on a long flight.
For a living being to be contaminated, radioactive material must be on or inside of their body. A contaminated living being is exposed to radiation released by the radioactive material on or inside their body. An uncontaminated living being can be exposed to radiation by being too close to radioactive isotopes or another contaminated living being, place or object.