12 radionuclides Flashcards
what are the objectives of this lecture?
-to learn about characteristics of radionuclides as environmental pollutants: what is unique about them? (hazardous properties due to physical makeup, not chemical)
-to understand their source, mechanisms of action, and human and environment health consequences of radionuclide contaminations
what is the overview of radiation?
-either ionizing (high energy, can ionize molecules in their path) or non-ionizing
-risks of injury from exposure to ionizing radiation (due to physical property)
what are the sources of radioactivity?
natural
-cosmic rays
-natural radioisotopes
anthropogenic
-nuclear reactors (used nuclear fuels) (weapons, development, energy production)
-waste from uranium mining and milling
-production of medical radioisotopes
-x-rays
what is the uranium mining, milling and usage sites in canada?
what are the types of radioactive waste?
low radioactivity waste (high volume):
-contains material with limited amounts of long-lived activity
-low-level waste requires isolation and containment for up to a few hundred years
intermediate radioactivity waste (low volume):
-typically exhibits levels of penetrating radiation and contains significant quantities of long-lived radionuclides
high radioactivity waste (low volume):
-includes used nuclear fuel and other wastes (e.g. fuel reprocessing wastes) that have been declared as radioactive waste
-used nuclear fuel is associated with penetrating radiation and contains significant quantities of long-lived radionuclides
-most hazardous
what is the radioactive waste production: globally and in canada?
what is the containment of radioactive waste in canada?
what are the types of ionizing radiation?
-alpha particles
-beta particles
-gamma rays
-X-rays
-neutron particles
what is the table of uranium decay series?
what are alpha particles?
-relatively large mass
-consists of two protons and two neutrons
-do not travel far: range in air is 1-2 inches
-offer minimal external hazard
-can cause significant regional cellular damage when internalized (inhaled or ingested)
what are beta particles?
-electrons/positrons emitted during decay
-half the charge of alpha particles
-travel further than alpha particles
-less dangerous internally, but still can cause significant regional injury
what are gamma rays?
-electromagnetic wave/ no charge
-ionize matter by direct interaction with orbital electrons
-highly penetrating
-can produce whole body exposure
-equally dangerous with external or internal exposure
what is the nature and intensity of the decay?
electromagnetic photons (gamma and x-rays)
-lowest energy
-high penetrating ability
beta particles
-higher energy
-less penetrating (2-3 mm of aluminum or 2-3 cm of flesh)
alpha particles
-highest energy
-stopped by a sheet of paper or outer skin surfaces
what are the intensity of the radioactive substance units?
SI unit: becquerel (Bq)
-number of atoms disintegrating per second
older units: curie (Ci)
-number of disintegrations per second in 1 g of radium
-1 Ci=3.7x10^10 Bq
what are the “biologically meaningful” units of radioactivity?
take into account the nature of radioactivity
-alpha: less penetrating but most damaging due to large mass
-beta: more penetrating but less damaging
-gamma: highly penetrating, damage similar to beta
SI unit: gray (Gy)
-amount of radiation causing of 1 kg of tissue to absorb 1 joule of energy
SI unit: sievert (Sv)
-takes into account the damaging potential of the absorbed energy
-“safe” annual dose for human beings is 1 mSv
what are the units of radiation dose/destructive potential?
-(dose in Gy) x QF = sievert (Sv)
QF= 1 for gamma, x-rays ad beta particles
QF= 20 for neutrons and alpha particles
what was the poisoning with polonium-210 (an alpha emitter)?
russian spy (worked for KGB)
-went to UK, then got poisoned by KGB
-found almost all internal organs had melted away
what are the effects of ionizing radiation on different taxonomic groups?
what is the sensitivity of tissues and organs to radiation?
from most to least sensitive:
-blood-forming organs
-reproductive organs
-skin
-bone and teeth
-muscle
-nervous system
-embryos and fetus are more sensitive than adults
what is the indirect effect and direct effect of radiation?
what is the mode of toxic action of radiation?
what are the physiological effects of radiation?
what are the factors affecting radionuclide toxicity?
what is the chernobyl case study?
-children and adolescent exposed have increase in thyroid cancer (iodide 131 was one of the ones released)
-clean up people gave increased rates of cardiovascular, cataracts and blood cancers
what was the research into birds around chernobyl?
what was the fukushima nuclear disaster in japan?
radioactivity released and fall-out:
-air: one-tenth of chernobyl disaster
-significant amounts also released into the ground and ocean waters
-contamination of I-131 and Cs-134/137 in drinking water and food, up to 200 miles from the nuclear plant
-farming abandoned in 12 mile evacuation zone
what is the graph of the fukushima-derived radionuclides in the ocean and biota off Japan?
what is the summary report on fukushima accident contaminants in canada?
how did they test butterflies?
what were the generational effects in the butterflies?
what is the case study of human heath risks associated with low level radioactive contamination in northern saskatchewan?
what is the human exposure risk of northern saskatchewan?
what were the effects of uranium mining and milling on benthic invertebrate communities in the athabasca basin of northern saskacthewan?
-the composition of some invertebrates (live in sediments) communities has changed due to exposure to uranium mining activities in northern saskatchewan
-the number of benthic invertebrate taxa downstream at half of the uranium mine/mill effluent release points was lower compared to the number of taxa observed in reference conditions
-taxon richness was lower in lakes in higher concentrations/activities of measured metals and radionuclides in the sediments
-the general decreasing trend in taxon richness with increasing metal concentration and radionuclides activity was consistent for both reference and exposure lakes: implying a natural background influence of these contaminants
-these effects are not just from radionuclide waste, but also metals
-already have high radiation due to Saskatchewan’s geolocation
what is EARMP? what were the results?
10-year summary report
-results have consistently demonstrated that water and traditional foods remain sale for consumption and that they continue to be safe and a healthy dietary choice for residents of the athabasca basin
what is dangerous in a third of saskatchewan home?
