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Lecture 6

EESA10 Lecture 6-8.docx

6 Pages
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Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic

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EESA10 FINAL EXAM Lecture 6: Radiation  We cant escape radiation  Background Radiation  natural radioactivity in the earth and by cosmic rays from outer space o Cant be controlled  Manmade Radiation  electronic products o X-ray machines, x-ray diagnostic, TV’s, microwaves, Radar devices, lasers o Can be controlled Ionised Radiation Health Effects  Radioactive material tha decay spontaneously produce ionizing radiation o Strip away electrons from atoms (create 2 charged ions) o Break some chemical bonds  Alpha, beta particles, gamma and x-rays (differ the amount of the energy they have) Health Effects from exposure to Radionuclides Stochastic Health Effects – Chronic  Long term, low level of exposure  Increase levels of exposure make these effects more likely to occur but do not inglucence the type of severity of the effect 1. Cancer – uncontrolled growth of cells  Damage at the cellular or molecular level 2. Changes in DNA – mutations  Teratogenic (fetus most sensitive in 8-15 week of pregnancy, smaller head or brain size, poorly formed eyes, mental retardation)  Genetic (passed from parent to child) Non-Stochastic Health Effects – Acute  Short term, high level of exposure  Increase levels of exposure make these effects more severe 1. Cancerous Health Effects 2. Radiation sickness – nausea, weakness, hair loss, skin burn or diminishing organ function, premature aging, death Nuclear Power Plant Accidents  Three Mile Island, Pennsylvania, 1979  Chernobyl, former Soviet Union, 1986 – had 10-20x higher dose od exposure than Three Mile Island’s accident Is Any Amount of Radiation Safe?  Some scientists say low levels of radiation are beneficial  How do we know it causes cancer? o 1910 observed that radiation cause skin cancer o Japanese atomic bomb blast survivors o Uranium miners o Medical treatments o Children more sensitive because they are growing more rapidly Chemical Properties of Radionuclides  Organs can not distinguish between radioactive and non-radioactive forms of element o Radioactive iodine in the thyroid o Calcium, strontium-90 and radium-226 accumulate in bones Nonionised Radiation Microwave Radiation  Detect speeding cars  Send TV and phone communications  Treat muscle soreness  Dry and cure plywood  Raise bread and doughnuts  Cook chips Microwave oven  Form of electromagnetic radiation  Used in cooking because they are absorbed by foods  Pass through glass, paper, plastic  Reflected by metal  Microwaves bounce back and forth within the metal interior until they are absorbed by food  Water molecules in food vibrate, producing heat that cook the food  Food is not radioactive or contaminated  Cook from outside, heat conduct inside  Cooks unevenly  Energy efficient  May keep more vitamins and minerals Smoke Detectors and Alarms  Ionisation chambers – small amount of radioactive material encapsulated in a metal chamber  Low but steady electrical current  Smoke disrupts the current and triggers the detectors alarm  Vary small radiation until the source stay in detectors apparatus Television Radiation  X-rays produced when electrons strike barrier while traveling in the vaccum as in a TV tube  Potential x-ray radiation  Most TV sets don’t give off measurable amount of radiation  No evidence of human injuries  Effects of low levels exposure is not known Cell Phones  No proof that they are absolutely safe  Emit low level of radio-frequency waves, lower when in standby mode Electric Power Lines  Generation, transmission and use of electric power  Electromagnetic fields surround any electrical device  Very low frequency Lecture 7: Biological Hazards Nontransmissible Diseases  CVD, Cancer, diabetes, asthma Transmissible Diseases  infectious agent  Growing germ resistance to antibiotics  High reproductive rate allow them to become genetically resistant quickly  Overuse of antibiotic  Antibiotics in food additive to boost livestock  Bacteria  TB, anthrax, different forms of Plague  Viruses  Yellow Fever, HIV, SARS, Bird Flu, Smallpox, West Nile  Protozoa  Malaria Bacterial Diseases Tuberculosis  2004 – 14.6 mil chronic active cases, 8.9 mil new cases, 1.6 million deaths (mostly in developing countries)  Differences in health care systems  Transmission – cough, sneeze, speak, kiss or spit of ill person  Symptoms – chest pain, coughing up blood, productive, prolonged cough for 3+ weeks, fever, chills, night sweats, appetite loss, weight loss, paleness and often a tendency to fatigue very easily Anthrax  Bacillus Anthracis – large spore forming bacteria  Produces toxin  3 major clinical forms 1. Cutaneous – on the skin  Most common, naturally occurring tyoe  After skin contact with contaminated meat, wool, leather from infected animals  Incubation period – 1-12 days  Begins as small raising bump, progresses into vesicle and then a painless ulcer  Fever, Headache, lymph glands swell  20% of untreated cases result in death 2. Inhalat
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