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Lecture 6

EESA10 - lecture 6 notes

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University of Toronto Scarborough
Environmental Science
Jovan Stefanovic

Lecture 6RadiationAll around usCannot escape or controlIt is a part of our planet1Background Radiationit is natural radioactivity in the Earth and by cosmic rays from outerspace It can lead to mutation but does not usually cause harm to humans2Manmade radiationcause by electronic products and is harmful to the human healthSome SourcesXrays machinesTV setsLasersMicrowavesThese sources are controllableManmade Radiation is only 18 of all emitted radiations of which 4 is emitted from nuclear medicines used to cure cancerNatural Radiation is 82 of all emitted of which 55 is emitted by RadonRadiation can be divided into 2 groups based on the amount of energy possessed by the radiation1IonizedHigh energy cosmic gamma rays etc it has short wavelengths However there is enough energy to break down chemical bonds and can harm our body2Non IonizedLow 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 scientistsHow does ionized radiation cause health effectsRadioactive material that decay spontaneously producing ionizing radiationoStrip away electrons from atomsoBreak some chemical bondsAlpha beta particles gamma and xrays differ in the amount of energy they haveHuman Health effects from to radionuclidesDivided two categories1Stochastic Health EffectsChronicLong term low level of exposureIncreased levels of exposure does not related to a high severity to the adverse effects of radionuclides but increases the likelihood of getting affectedICancer uncontrolled growth of cells Radionuclides and other carcinogens interfere with the genetic mechanism of cell growth at the cell and molecular levelIIChanges in DNA leads to mutation It is teratogenic This means fetuses that are constantly exposed to radiation suffer It can lead to a small head size mental retardation and disability2Nonstochastic health effectsAcuteShort term high level of exposureIncreased levels of exposure leads to more severe adverse effects eg nuclear power plant accidentsIts effects are best studied of Japanese survivors of the Hiroshima and Nagasaki bombings in WWIIICancerous Health Effects Maybe and maybe not Some suggest children who are exposed may experience such cancersIIRadiation sickness instant weakness discoloration skin burn hair loss premature aging and can lead to death
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