EESA10H3 Lecture Notes - Lecture 6: Microwave Oven, Acute Radiation Syndrome, Intellectual Disability
14 Jun 2018
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EESA10: Lecture 6 – Radiation & Human Health
Radiation
1. Background Radiation – natural radioactivity in Earth + by cosmic rays from outer space
a. Can’t be controlled; cannot escape radiation
2. Manmade Radiation – can be controlled
Electronic products
a. X-ray machines
b. X-ray diagnostic
c. T.V sets
d. Microwave ovens
e. Radar devices
f. Lasers
- Ionized radiation – radioactive material that decay spontaneously produce ionizing radiation
o Strips away electrons from atoms (create 2 charged ions)
o Breaks chemical bonds
o Alpha, beta particles, gamma + x-rays (differ in amount of energy they have)
- Non-ionized radiation
Health Effects from Exposure to Radionuclides:
1. Stochastic health effects – Chronic
a. Long term, low lvl of exposure
b. Increased lvls of exposure make these effects more likely to occur but don’t
influence type/severity of the effect
c. Changes in DNA – mutations
i. Teratogenic (fetus most sensitive in 8-15 wk of pregnancy, smaller
head/brain size, poorly formed eyes, + mental retardation)
ii. Genetic (passed from parent to child)
d. Cancer - Damage @ cellular/molecular lvl – uncontrolled growth of cells
2. Non-stochastic health effects – Acute
a. Short term, high lvl of exposure
b. Increase lvls of exposure make these effects more severe
c. Radiation sickness – nausea, weakness, hair loss, skin burn/diminishing organ
function, premature aging, death
d. Cancer – Damage @ cellular/molecular lvl – uncontrolled growth of cells
- Carcinogenesis
Carcinogen – any agent that increases cancer risk @ any stage in process
Cancer: a disease in which cells multiply w/out restraint
o Tumour invades tissue of origin; metastasis into other tissues
o Cancer results from an accum. of mutations
Mutation: change to DNA of a cell
Key mutations in carcinogenesis:
Increase activity of genes that instruct the cell to divide (oncogenes); or
decrease activity of genes that instruct the cell to stop dividing (tumour
suppressor genes)
o Simple view of stages in carcinogenesis
Initiation – initial mutation in a cell either…
Enhances instructions to cell to divide
Decrease instructions to stop dividing
Promotion – initiated cell= stimulated to divide becoming a benign tumour
Progression – mutations cell division malignant tumour
- Chemical Properties of Radionuclides:
o Organs can’t distinguish b/w radioactive + nonradioactive forms of element
Radioactive iodine in thyroid
Calcium, strontium – 90 + radium – 226 accum. in the bones
o Any amount of radiation safe?
Some scientist think that low lvls of radiation are beneficial
How do we know radiation causes cancer?
1910 scientists observed radiation causes skin cancer
Uranium miners
Japanese atomic bomb blast survivors
Medical treatments
Children more sensitive b/c they are growing more rapidly
Nuclear Power Plant Accident
