Chapter 6.docx

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University of Toronto Scarborough
Environmental Science
Jovan Stefanovic

Chapter 6-Radiation and Human Health Midterm = MC with T/F questions (~70-80 questions); majority are from her lecture notes or talk (90%); 15% = textbook (no %, numbers but general concept); lectures 1-6 are on exam (today is last lecture) Slide 2: Radiation and Human Health - Humans have been exposed to radiation since the beginning of civilization b/c of natural radiation (comes from planet earth and space in the form of cosmic rays); we can’t do anything about it = cannot control/reduce this radiation - This doesn’t change our DNA makeup that much - Last 50 years = new kind of radiation = man-made radiation = comes from any electronic product; good thing = we can control this form of radiation - Most frequent human radiation exposure is radon - Most prominent man-made radiation is medical x-rays at 11% Slide 3: Ionizing Radiation Exposure to the Public - Huge amount is natural radiation (large part of it is Radon-55%; exists in air, drinking water, showers, and it’s a radioactive gas) Slide 4 - Divided into Ionised and Non-ionised radiation - Ionised: of very high energy o Short wavelengths (cosmic rays-ultraviolet rays-ref diagram) o High in energy = these waves have enough energy to elevate electrons from molecules; break chemical bonds and damage DNA causing mutations o Genotoxic and carcinogenic - Non-ionised: o Low energy waves o We don’t know the long-term effects of these waves Slide 7 1. Stochastic Health Effects-Chronic - chronic b/c it’s long-term exposure to the low levels of radiation (not via accident = w/o knowing that you are exposed to it); no initial health effects - but later on, health effects will be detected - linear-no threshold-hypothesis: all exposure to radiation presents some risk to human health - increase in dose of radiation will not change the type of illness (same severity, same type) - cancer = damage at molecular/cellular level - 2 groups of mutations o Teratogenic: mutations if the unborn child is exposed inside the mother’s womb and then later on, has a mutation (dna changed introutero). These types of mutations will not be transmitted to future children) o Genetic: transferred from parent to child Slide 8 - These are accidental mutations = nuclear power plants etc. - Debate on whether there is cancerous health effects - High level of radiation causes radiation sickness/poisoning - Can experience premature aging due to radiation sickness Slide 9 - Literature did not find that the radiation released during these accidents increased the risk of cancer - Direction of wind during the time of 1986, blew the fumes to the northern part of Europe – Sweden, Norway, Denmark etc had increasing levels of radiation - Not many years after this accident, there was an increasing number of thyroid cancer in children especially in children who were about 4 years old at the time of the accident. After 10 years of the accident, these children developed symptoms of thyroid cancer Slide 10 - Circled ones = most at risk to radiation * ON EXAM* Slide 11 - First indication that radiation caused adverse health effects was demonstrated in uranium miners = noticed that they were suffering from similar diseases (shown to be strongly related to uranium exposure) - Also noticed that some radiation caused skin cancer - Later on, after WWII, victims of the Nagasaki and Hiroshima bombing were important source for scientific research - Children more sensitive to radiation b/c they are growing (cancer is growing of the cells and since children are growing, they are at highe
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