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Lecture 6

EESA10H3 Lecture Notes - Lecture 6: Microwave Oven, Acute Radiation Syndrome, Electromagnetic Field

Environmental Science
Course Code
Jovan Stefanovic

of 6
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,
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
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
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
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
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
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. Inhalation
Most lethal form
Incubation period 1-60 days
Starts as viral respiratory illness: sore throat, mild fever, muscle aches
May progress to respiratory failure and shock with developing
75% of cases result in death even with all possible supportive care
3. Gastrointestinal
Consumption of raw or undercooked contaminated meat