According to Bushong (2009), radiation is an energy that moves through space or matter at a very high speed. This energy can be in the form of particles, such as alpha or beta particles, which are emitted from radioactive materials, or waves such as light, heat, radiowaves, microwaves, x-rays and gamma rays. He also mentioned that radioactive materials which is also known as radionuclides or radioisotopes are atoms that are unstable. So, there is a tendency for unstable atoms to change into a stable form, but when they change form, they release radiation. Radiation that can produce ions when it interacts with matter is called ionizing radiation (Mettler & Upton, 1995). They said that ions are the charged particles that are produced when electrons are removed from their positions in the atoms. According to them, alpha particles, beta particles, x-rays and gamma rays are forms of ionizing radiation. On the other hand, radiation that is not capable of producing ions in matter is known as nonionizing radiation. (Mettler & Upton, 1995) Radiation and radioactive materials are part of our environment. Bushong (2009) implied that radiation in the environment comes from both cosmicradiation that originates in outer space, and from radioactive materials that occur naturally in the earth and in our own bodies. Hendee (1979) said that, today, radiation is a common and valuable tool in medicine, research and industry. It is used in medicine to diagnose illnesses, and in high doses, to treat diseases such as cancer. Also, high doses of radiation are used to kill harmful bacteria in food and to extend the shelf life of fresh produce. Based from him, radiation produces heat that is used to generate electricity in nuclear power reactors. Radioactive materials are used in a number of consumer products, such as smoke detectors and exit signs, and for many other research and industrial purposes. (Hendee, 1979) There are great deals about radiation as a useful product in treating lots of illnesses and body deficiencies. Hendee and Edwards (1996) told that in every high radiation doses, a human cell can be damaged so severely that it will die, where in lower doses, the cell can repair the damage and survive. But, if the repair is faulty, the cell could give incorrect information to the new cells it produces. They pointed out that the exposure to radiation may lead to different health effects. According to them, the type and probability of the effects produced depend on the radiation dose received. This could result in health problems for the exposed individuals or may also reflect in genetic defects that may show up in their descendants. Generally speaking, there are two types of health effects from radiation, the threshold and non-threshold effects.
Mettler and Upton (1995) stated from their study that high doses of radiation that was received in a short period of time result in effects that can be noticed after exposure and these are called as threshold effects. They implied that a certain dose range must be exceeded before they can occur. These effects include radiation sickness and death, cataracts, sterility, loss of hair, reduced thyroid function and skin radiation burns. The severity of these effects increases also the size of the dose. Based from the book entitled as Medical Effects of Ionizing Radiation that was written by Mettler and Upton (1995), the radiation sickness is at doses of about 60 rem and 5% of exposed individuals may vomit. This increases to about 50% at 200 rem. On the other hand, at doses between 300 and 400 rem and without medical treatment, there is a 50% chance that a person will die within 60 days. With proper medical care, however, based from their research, some people exposed to 1,000 rem could survive. On cataracts, a single exposure between 200 and 500 rem could cause cataracts (clouding of the lens of the eye). Mettler and Upton (1995) said that if an...