Lecture 6: Radiation and Human Health
We can not escape radiation
1. Background radiation - Natural radioactivity in the Earth and by cosmic rays from outer
space. Cannot be controlled
2. Manmade radiation - electronic products:
• X-ray machines: different kind of equipment used in labs for different analysis and research.
• X ray diagnostic: Diagnostic stuff for checking the internal body structures
• Television sets
• Microwave ovens
• Radar devices
• Can be controlled
Radon is a gas which affects us so much (55% radiation)
2 groups of radiation:
Ionised radiation: so much energy that can change atoms of some other chemicals. They
can push out electrons out of their atoms and produce ionized form of electrons.
Non-ionized radiation: Low energy radiation (High wavelength). Don’t have enough
energy to remove electrons from the atoms.
www.notesolution.com How does ionised radiation cause health effects?
_ Radioactive material (uranium etc) that decay spontaneously produce ionizing radiation
_ Strip away electrons from atoms (create two charged ions)
_ Break some chemical bonds
_ Alpha, beta particles, gamma (very dangerous) and x-rays (differ in the amount of energy they
Health effects from exposure to radio nuclides:
1. Stochastic health effects - CHRONIC
• Long term, low level of exposure (if higher levels: severity won’t change..Will be the same)
Just risks of getting those illnesses can be higher
• Increase levels of exposure make these effects more likely to occur but do not influence the
type or severity of the effect
i. Cancer- uncontrolled growth of cells
• Damage at the cellular or molecular level
ii. Changes in DNA- mutations
• Teratogenic (birth defects: most sensitive in 8- 15 week of pregnancy, smaller head or brain
size, poorly formed eyes, mental retardation)
• Genetic (passed from parent to child)
2. Non-stochastic health effects - ACUTE
• Short term, high level of exposure
• Increase levels of exposure make these effects more severe
i. Cancerous health effects, Yes or No
ii. Radiation sickness (nausea, weakness, hair loss, skin burn or diminishing organ function,
premature aging, death)
Nuclear power plant accidents
Three Mile Island, Pennsylvania, 1979: radiation level was so low: failed to promote chronic
Chernobyl, former Soviet Union, 1986
Chernobyl accident had 10-20 times higher dose of exposure than Three Mile Island’s accident
The effect of different doses of radiation on the human body after acute, whole-body exposure.
Radiation felt even today. Mutations are not rare.
Is any amount of radiation safe?
_ Some scientist think that low levels of radiation are beneficial
_ How do we know radiation causes cancer?
_ In 1910 observed that radiation cause skin cancer
_ Japanese atomic bomb blast survivors
_ Uranium miners
_ Medical treatments
www.notesolution.com _ Children more sensitive because they are growing more rapidly: their cells are growing more
quickly than adults and this more affected.
Chemical properties of radionuclides
_ Chemical properties determine where health effects occur
_ Organs cannot distinguish between radioactive and non radioactive forms.
Lead can be radioactive and cannot. Iron can be same but it is essential for human body
Radioactive and non-radioactive forms of element
1. Radioactive iodine in the thyroid: Normal function requires iodine. Nonradioactive I is fine.
Radioactive I can cause cancer.
2. Calcium (not radioactive) but other two, strontium-90 and radium-226 (similar properties
compared to Ca and so accumulate in bones)
_ Natural radioactive break down of uranium in soil, rock and water
_ Causing lung cancer
_ Odorless, colorless gas
_ Indoor air pollution
_ The second leading cause of lung cancer in the US today (carcinogenic)
Nonionised radiation: Displays low energy but still dangerous
_ To detect speeding cars
_ To send telephone and television communications