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Lecture 6

ENV332H5 Lecture Notes - Lecture 6: Microcephaly, Outerspace, Iodine

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Patricia Houston

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Lecture 6
All around us
Cannot escape or control
It is a part of our planet
1. Background Radiation – it is natural radioactivity in the Earth and by
cosmic rays from outerspace. It can lead to mutation but does not
usually cause harm to humans
2. Manmade radiation – cause by electronic products and is harmful to
the human health
Some Sources:
X-rays machines
TV sets
These sources are controllable
Manmade Radiation is only 18% of all emitted radiations of which 4% is
emitted from nuclear medicines (used to cure cancer)
Natural Radiation is 82% of all emitted of which 55% is emitted by Radon.
Radiation can be divided into 2 groups based on the amount of energy
possessed by the radiation.
1. Ionized – High energy (cosmic, gamma rays, etc); it has short
wavelengths. However, there is enough energy to break down
chemical bonds and can harm our body.
2. Non Ionized – Low energy (TV, microwaves, etc); it has long
wavelengths. There is not enough energy to rearrange chemical
arrangement. The affects it has on human health is still debated by
How does ionized radiation cause health effects?
Radioactive material that decay spontaneously producing ionizing radiation
oStrip away electrons from atoms
oBreak some chemical bonds
Alpha, beta particles, gamma and x-rays (differ in the amount of energy they
Human Health effects from to radionuclides
Divided two categories
1. Stochastic Health Effects – Chronic
Long term, low level of exposure
Increased levels of exposure does not related to a high severity
to the adverse effects of radionuclides but increases the
likelihood of getting affected
I. Cancer: uncontrolled growth of cells. Radionuclides and
other carcinogens interfere with the genetic mechanism
of cell growth at the cell and molecular level
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