Radiation, and Radiation Terror
Types of Radiation��Ionizing radiation− Alpha, beta.−gamma rays , X-rays. ��Non-ionizing radiation−Electromagnetic: UV, microwaves, EMFs
Three types of ionizing radiation and their penetrating power
Sources of Radiation Exposure:Natural sources : that are untroubled by human activities−Examples include the sun (UV and cosmic x-rays) and the soil (radon). Man-made sources :are those specifically produced by man−Examples include medical devices, consumer products, and nuclear power plants
Radon
��Noble gas��Radioactive��Gives rise to progeny that are themselves radioactive solids stick as dust particles in the air and may inhaled and increase the risk of developing lung cancer.��These progeny deposit in the lungRadon
The alphas emitted by radon progeny are particularly “dangerous” cause it gives a very high dose to radiosensitive epithelial stem cells. Within a short “range” in tissue (~ 2–4 cell diameters)Radon gas can enter a home from the soil under the house by process of diffusion through concrete floors. that children may be more sensitive to radon. This may be due to their higher respiration rate and their rapidly dividing cells, which may be more vulnerable to radiation damage.Ultraviolet Light
��Ultraviolet light: non-ionizing radiation��The sun is a major source of ultraviolet lightTypes of Ultraviolet Light��UV-A :−Tanning, skin cancer (?)��UV-B : −Sunburn, skin cancer, cataracts, immune suppression��UV-C : DNA damage−Basal cell carcinoma: Doesn’t usually metastasize−Squamous cell carcinoma: Metastasizes to regional lymph nodes−Malignant melanomas: Rapid overall metastasisExtremely Low-Frequency EMFs
radar and communication equipment. No evidence of direct DNA damage, but EMFs produce changes in DNA synthesis and RNA transcription ELF EMFs are possibly carcinogenic to humans
Radiation Poisoning
��Small area contamination (localized release of radioactivity��Larger release in air or waterMedical Issues��Acute−“Usual” medical problems for bomb-type attack (injuries, burns)−Acute radiation syndromes−Patient internal contamination��Delayed−Radiation carcinogenesisNote: Must consider both acute and delayed effects of in utero irradiationIonizing Radiation and Cancer Causation
Leukemia−Cancers in A-bomb survivors−Patients irradiated for ankylosing spondylitisThyroid cancer−Children irradiated for enlarged thymus−Children irradiated for tinea capitisLung cancer- minersIonizing Radiation and Cancer Causation
Bone tumors−Radium dial paintersLiver tumors−Children irradiated for tinea capitisSkin cancer−X-ray workersRadiation Carcinogenesis Risk Estimates
Most commonly accepted risk estimates: are based on a relative risk model, with excess cancer mortality dependent on dose, age at exposure, time since exposure, and gender. this model assumes increasing excess cancers with increasing ageMechanisms for Radiation Carcinogenesis
Ionizing radiation Cell Death OR Cell Damage ↙ ↘ Repair Altered functionPsychosocial Issues
��Radiation as an “invisible toxin”—may have more for psychosocial than physical impact��Acute and chronic psychosocial reaction is a central concern��Risk perception is high-risk—plus terrorist (i.e., non-accidental) event��High-risk groups for psychosocial harm—children, mothers with young children, emergency workers, clean-up workersNuclear Power and Radioactive Waste Disposal
types of Radioactive Waste Generated Annually;Fuel removed from commercial reactorsHighly radioactive—from fuel processing, IONIC REACTORSResidues and waste after uranium mining and extraction from ores
High-Level Radioactive Waste Disposal
��Permanent disposal system not fully developed��Generally stored “temporarily” on-site in pools of water��Disposal involves complex technical, political, and social issues −Must be perfectly contained (toxicity)−Secured as contains fissionable material (uranium or plutonium) necessary for nuclear weapons−Guarded for a very long time span (long half-life)−Difficulties transporting to permanent siteHigh-Level Radioactive Waste Disposal (cont.)
��Geologic disposal−Isolate nuclear waste in a stable rock formation 1,000 feet underground.��Sub-sea bed disposal−Isolate nuclear waste in deep-sea sediments 3,000–5,000 meters deep��Other alternatives−Bury in Antarctic ice sheet−Send into space−Keep in large water pool��The main obstacles to management progress include; lack of money (e.g., Superfund), reluctance to accept responsibility, and incomplete science (e.g., epidemiologic studies)