Sunday, April 12, 2015

Units of Exposure and Biological Effects



Ionizing radiation is “radiation that has enough energy to remove electrons from atoms or molecules when it passes through or collides with some kind of material.” Ionizing radiation is measured in terms of strength or radioactivity of the radiation source, the energy of the radiation, the level of radiation in the environment and the radiation dose or the amount of radiation energy absorbed by the human body. “From the point of view of the occupational exposure, the radiation dose is the most important measure.”

One term that is used in describing ionizing radiation is roentgen. Roentgen “is an indicator of the degree of ionization that produces one unit of charge in one cubic centimeter of dry air. One roentgen is the amount of x- or gamma radiation that produces one unit of charge in one cubic centimeter of dry air.” Another unit that can be used for measuring gamma ray intensity in the air is air dose or absorbed dose rate in the air in grays per hour unit. “This unit is used to express gamma ray intensity in the air from radioactive materials in the earth and in the atmosphere.”

Radiation comes from many different sources and people can be exposed at different levels. Since there are multiple sources of exposure there are various biological effects of ionizing radiation. “One characteristic of ionizing radiation on human body is that the energy absorbed is low but the biological effects are serious.” Two effects of ionizing radiation are somatic and genetic effects.  Somatic effects “take place in the cells and tissues of the individual who was exposed to the ionizing radiation.” Genetic effects focus on the biological changes that if exposed can be passed down through genetics. “When genetic cells are irradiated, the chromosomes or DNA of the cells may be affected which may lead to genetic mutations, chromosome aberrations or changes in the number of chromosomes in the cells.”



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