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Radiation and Living Organisms

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    Athletes must have their bodies in top condition in order to compete. Ordinary people want to live long and be happy. In order to do this, good health practices are necessary. But what happens when we are exposed to environmental factors that we do not have direct control over? Ionizing radiation is one of these factors.

    Ionizing radiation has energy high enough for an electron to be removed from its orbit. Three types were discovered at the end of the nineteenth century: the alpha, beta, and gamma rays. Atoms give off these types of radiation when they are radioactive and decompose. Alpha rays are the most massive and positively charged. Beta rays are much less massive and negatively charged. Gamma rays have no mass or charge. Experiments by Ernest Rutherford and later experiments showed that alpha rays are helium nuclei, beta rays are electrons, and gamma rays are photons. These particles have different penetration abilities. Paper stops alpha waves. Beta rays may penetrate 1 mm of aluminum. Gamma rays can penetrate several millimeters of lead.

    How does radiation affect living organisms at the cellular level? What happens when these substances give off particles and waves and living tissue is exposed to it? Ionization from radiation changes atoms and molecules. This changes molecules at the cellular level and causes damage.

    Let us look at a specific case. Energy can be directly transferred to DNA, but it usually is transferred through the ionization of water:

    \[\ce{H2O + radiation -> H2O+\cdot + e-}\nonumber\]

    Also the water molecule can be placed in an excited state:

    \[\ce{H2O + radiation -> H2O*}\nonumber\]

    These three species begin reacting with other molecules in the cell and with each other. They react to produce highly reactive radicals. (Radicals are unpaired) They are:

    OH. H. and e-

    These radicals are highly reactive (especially the first two) and they react with other molecules in the cell. DNA is specifically susceptible to changes and can have single strand breaks, double strand breaks and other changes. This damage is normally repaired. If it is not completely repaired, changes can be transferred to new cells through cellular replication. Genes in the DNA can become mutated and cause the cells to divide and multiply uncontrollably which can lead to cancer. Other things can happen if the damage is too widespread. Noticeable effects in organs are evident and can lead to death. A third possibility is that changes in the DNA can be transferred to offspring and result in genetic disorders. This happens to people who have been exposed to higher than safe levels of radiation.

    How does this affect a person, especially when he or she is involved in sports? We all know that athletes must be in top shape in order to compete well. If illness, injury, or disease sets in, the individual is not well qualified to compete. It will adversely affect health. Take for instance the circulatory system. The circulatory system helps to maintain homeostasis and pH. It circulates necessary nutrients and electrolytes throughout the body as well as supplying oxygen to all the tissues. If it has been damaged by radiation the human body will not receive all the nutrients and oxygen it needs to function, or the extra energy it needs for competitive sports. As a vital part of the circulatory system, the heart must be in top shape to pump the blood throughout the body. If the cells of the heart or other organs have been adversely affected or damaged by radiation, then they will not be able to perform their functions properly. Fatigue can set in and the body will not respond well.

    As you can see, radiation is harmful to the human body. Humans that are exposed to ionizing radiation experience different levels of negative effects. Therefore, it is necessary that we minimize exposure and practice good health habits to counteract harmful effects.

    From ChemPRIME: 4.7: Radiation

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