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Lecture

Radiation

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Department
Environmental Studies
Course
ENST200
Professor
Scott Wilson
Semester
Fall

Description
• Radiation is everywhere, all around us. We cannot escape radiation. But the question is what type and how much radiation is there. • Even if we are walking outside in the woods, we are still exposed to some radiation, because of Background Radiation: Something that is produced and emitted from outer space. Natural radioactivity in the earth and by cosmic rays from outer space. This type of radiation cannot be controlled. We are always exposed to it. It has existed for hundreds of thousands of years. • Something that we can control is man made radiation (Electronic devices, appliances, etc.). (Note: Nowadays, engineers have found technologies to protect us from most of this radiation). Examples of some man-made devices that emit different types of radiation include: - X-ray machines (different kind of equipment used in labs for analysis, for example, CCA can also be detected using X-ray) - X-ray Diagnostic (X-ray used for diagnostic of different body parts) - Television sets - Microwave ovens - Lasers Ionizing radiation exposure to the public • Natural radiation sources consists of 82% of total measurable radiation • Man-made radiation is just 18%. Medical x-rays, nuclear medicine can treat some illnesses and some other types of radiation. What is surprising is that Radon (gas in indoor air) makes up 55% of total radiation. Radiation and Human Health • We have two big groups of radiation: 1) Ionized Radiation (Cosmic, Gamma, X-rays): This is radiation that has so much energy that can change atoms on some other chemicals. They can push electrons out of their atoms and produce ionized form of that element. They are very strong as they have so much energy. (Note: On electric spectrum, elements that are very high in energy have short wavelength, elements with low energy (non-ionized) have long wavelength.) 2) Non-Ionized Radiation (Radio waves, TV waves, Microwaves): This type does not have enough energy (low in energy) and they cannot remove electrons from atoms. Ionized Radiation • Affect of this radiation is obvious. All scientists agree that this radiation is really harmful. How does it affect human health? First, the radioactive material (like Uranium), decays naturally and spontaneously, and produces ionizing radiation. This ion radiation, strips away electrons from atoms (create two charged ions) • It can also break some chemical bonds. This is important for human body as it consists of water and chemicals. Examples: alpha, beta particles, gamma and x- rays. These examples differ based on the amounts of energy they have. Health effects from exposure to radionuclides There are 2 different kinds of health effects. 1) Stochastic effect – Humans exposed to long term, lower level of radiation. This is most problematic because it is very hard to detect and to know what will happen to our health after long time exposure to lower level of radiation. Hard to detect and not 100% known. What is known is that if the amount of radiation increases the severity of this affect will not change and will stay the same and the type of illnesses will be the same. But the risk to get that illness will increase. Risk of getting cancer will be higher. This amount of radiation is proven to cause cancer. 2 effects associated with this Stochastic:  Cancer is uncontrolled growth of cells (any kinds of cells as there are many kinds of cancers). Naturally in our physiological functions, our cells divide and produce new ones to replace old ones. This natural physiological process is controlled by our genetic material. But if certain radiation disrupts this natural process, it will cause cancer. Basically, cells keep on growing without reason. And this reason is radio nuclides.  Another effect that can be caused is changes in DNA (changes to genetic material). Two problems can happen because of this. One is Teratogenic changes and another is genetic changes (mutations). What are teratogenic effects: birth defects. Mother is exposed for long term to lower level of radiation (most sensitive in 8- 15 week of pregnancy) ; her unborn child will have some problems like smaller head or brain size, poorly formed eyes, mental retardation. Genetic mutations are changes that can be transferred from the parent to the child. Teratogenic changes cannot be transferred to the child, but the offspring is affected anyways, which we see when child is born. 2) Non-Stochastic effect – These are acute effects. These effects are seen in human
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