Radiation Saftey Series 4

8/14/2019 Radiation Saftey Series 4

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Radiation Safety Series 4

Radiation Hazards


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Human Exposure to Radiation

Annual DoseSource mrem/yr

Exposure from natural backgroundCosmic rays (sun and outer space) 28Building materials 4

Human body 25The earth 26

Approximate total annual exposure 100


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Annual DoseSource mrem/yr

Exposure from man made sourcesMedical (mostly diagnostic x-ray) 90Fallout from atomic bombs 5

Consumer products (mostly color TV) 1__ Approximate total annual exposure 100


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Occupation radiation source averagesRadiography company workers 440Gamma Radiographers 1,000

CNRP Report No. 45, 1975 and NCRP Report No. 45, 1977


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Radiation vs. Contamination

RadiationThe emission of waves or fast moving

particles through spaceRadioactive Contamination

Material that is radioactive anduncontrolled. It may soil surroundingareas and become airborne


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Ionization of Body Tissue

X-ray, gamma andneutron penetrate the

body to differentdegrees

Through the ionization process energy isabsorbed by the tissue

This causes damage tothe bodys complexsystemshttp://www.ratical.org/radiation/NRBE/NRadBioEffects.html


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Biological Effects

How much physical energy does this largedose of ionizing radiation represent?

Since all forms of energy interconvert, wecan use heat units as a basis of comparison

A CALORIE is (by definition) the amount

of heat needed to raise the temperature of one gram of water by one degree Celsius.The conversion from ergs to calories is:


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Biological Effects

1 erg = 2.39 x 10 -8 calories. Now since 1 rad (of ionizing radiation)

deposits 100 ergs of energy per gram,400 rads will deposit

40,000 = 4 x 10 4 ergs per gram,

which is equivalent to (4 x 10 4) x (2.39 x 10 -8) = 9.56 x 10 -4

calories per gram


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Biological Effects

This amount of energy would raise thetemperature of one gram of water by lessthan 0.001 o C !

(That is, less than one one-thousandth of adegree Celsius!) It is an imperceptible

amount of heat


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Biological Effects

This calculation highlights the enormousdifference between energy in the form of heat and

energy in the form of ionizing radiation. An amount of energy which is absolutely

inconspicuous in one form can be lethal inanother. When a radioactive material gives off anydegree of perceptible heat, it is capable of killingthousands of people.


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What is the reason for the

difference?It is because the energy of ionizing radiation is notuniformly distributed among all the molecules of agram of tissue, the way thermal energy is. Instead,ionizing energy is transferred to just a fewelectrons in a relatively few molecules, therebydisrupting the molecular basis of living cells. Thatcellular damage is then multiplied and amplified

by normal -- and abnormal -- biological processes.

http://www.ccnr.org/ceac_B.html


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Radiation Damage

Cell damage due to radiation Exposure: Increases as cell reproduction rates

increases Decreases as the degree of cellular

differentiation increases Decreases as cells mature


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Human Cell Sensitivity

1. White Blood Cells2. Immature Red Blood Cells3. Digestive System Lining Cells4. Cells of the Gonads

5. Blood Vessel Cells6. Bone, Muscle and Nerve Cells

Lowest number has the highest sensitivity


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Nature of Cell Damage

Cell damage due to radiation exposure canoccur in the following ways:

2. Mitosis delayed or stopped (cell division)3. Cell Injury may be temporary or

permanent

4. Cell death5. Chromosome Breakup6. Temporary or permanent cell dysfunction


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Categories of damage

Somatic effectsthe physical effects to the body resultingfrom cell damage

Genetic effectsmutations caused by damage to the germline (inheritance)


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Radiation Damage Factors

Rate the dose is administered5 rem per quarter for 40 years = 200rem. 200 rem in one dose may be fatal. Damaged cells are replaced quickly.

2. Extent the body is exposedA large dose over the whole body may cause death. A large dose on a small part of the body will damage that partand not cause death.

5. Part of the body exposedHands, forearms, feet and ankles are allowed 18.75 rem per quarter. Whole body is only allowed 1.25 rem.

7. Age of individual18 years of age and younger are in a high cell growth stage9. Biological differences

Biological response is different from individual to individual


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Effects of Radiation Dose

The minimum lethal dose of radiation exposure isapproximately 200 rem. By comparison,

background radiation exposure in the UnitedStates is about 360 mrem per year. Whenappropriate medical care is not provided, themedian lethal dose of radiation is estimated to be

350 rem. Modern medical therapy dramaticallyimproves the survivability of radiation injury.


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The following probable outcomes depend on radiationexposure amounts:

For 1000 rem or more: Immediate death occurs . For 600-1000 rem: Weakness, nausea, vomiting, and

diarrhea are followed by apparent improvement. After several days, fever; diarrhea; hematochezia; hematemesis;hematuria; and hemorrhage of the larynx, trachea, bronchi,or lungs may occur. Death results in about 10 days .Autopsies show destruction of hematopoietic tissues,including bone marrow, lymph nodes, and spleen, andswelling and degeneration of epithelial cells of theintestines, genital organs, and endocrine glands.


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For 250-600 rem: Nausea, vomiting, diarrhea, epilation (loss of hair),weakness, malaise, hematemesis, hematochezia, hematuria, epistaxis,

bleeding from gums and genitals, subcutaneous bleeding, fever,

inflammation of the pharynx and stomach, and menstrualabnormalities occur. Marked destruction of bone marrow, lymphnodes, and the spleen causes a decrease in blood cells, especiallygranulocytes and thrombocytes. Radiation-induced atrophy of theendocrine glands, including the pituitary, thyroid, and adrenal glands,occurs. From the third to fifth week after exposure, death is closelycorrelated with the degree of leukocytopenia. More than 50% of patients die in this time period . Survivors may develop keloids,ophthalmologic disorders, blood dyscrasias, malignant tumors, and

psychoneurologic disturbances.


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For 150-250 rem: Nausea and vomiting occur on the firstday. Diarrhea and skin burns are probable. Apparentimprovement is noted for about 2 weeks thereafter. Fetal or embryonic death occurs in pregnant women.Symptoms of malaise are noted, as described above.

Persons in poor health prior to exposure or those whodevelop a serious infection may not survive. A previously

healthy adult recovers somewhat in about 3 months butmay have permanent health problems, may develop cancer or benign tumors, and will probably have a shortenedlifespan. Genetic and teratogenic effects have been noted.


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For 50-150 rem: Acute radiation sickness and burns are less severe than at the higher exposuredose. Spontaneous abortion or stillbirth occurs.Tissue damage effects are less severe. Reductionin lymphocytes and neutrophils leaves theindividual temporarily vulnerable to infection.Genetic damage to offspring, benign ormalignant tumors, premature aging, andshortened lifespan are possible. Genetic andteratogenic effects have been noted.


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For 10-50 rem: Most persons experiencelittle or no immediate reaction. Sensitive

individuals may experience radiationsickness. Transient effects

http://www.emedicine.com/emerg/topic934.htm


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4 clinical stages of radiation

exposureEach of the acute radiation syndromes (ie, hematopoietic,

gastrointestinal, neurovascular) manifests 4 clinical stages.Depending on the dose of radiation absorbed, these stages

may be of varying lengths. The prodromal phase begins at the time of exposure and

lasts for approximately 1-4 days. The prodrome ischaracterized by a relatively rapid onset of nausea,vomiting, and malaise. Radiogenic vomiting may easily beconfused with psychogenic vomiting that often resultsfrom stress. In high-dose exposures, the length of the

prodromal phase may be considerably shortened andreplaced by the manifest illness phase. A very short to nolatent period may occur, as described below.


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stages of radiation exposure

The latent period represents an interval of apparent well- being that lasts for 2-6 weeks but decreases markedly asthe dose rate and the total dose are increased. Cliniciansshould not be encouraged by this apparent improvement inclinical status.

Manifest illness is characterized by the clinical symptomsassociated with the major organ system injured (ie,

marrow, intestinal, neurovascular). Recovery or death follows.

http://www.emedicine.com/emerg/topic934.htm


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Works Sited

Radiation Safety Training Series Part 1: Radiation, RudarmelEnterprises, inc. Lake Oswego, Oregon

CNRP Report No. 45, 1975 and NCRP Report No. 45, 1977http://www.ratical.org/radiation/NRBE/NRadBioEffects.htmlhttp://www.ccnr.org/ceac_B.htmlhttp://www.emedicine.com/emerg/topic934.htm

Documents

Radiation Saftey Series 4