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 lung

Radon  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 light Types 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 metastasis

Extremely 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 water Medical Issues Acute −“Usual” medical problems for bomb-type attack (injuries, burns) −Acute radiation syndromes −Patient internal contamination Delayed −Radiation carcinogenesis Note: Must consider both acute and delayed effects of in utero irradiation

Ionizing Radiation and Cancer Causation  Leukemia −Cancers in A-bomb survivors −Patients irradiated for ankylosing spondylitis  Thyroid cancer −Children irradiated for enlarged thymus −Children irradiated for tinea capitis  Lung cancer - miners

Ionizing Radiation and Cancer Causation  Bone tumors −Radium dial painters  Liver tumors −Children irradiated for tinea capitis  Skin cancer −X-ray workers

Radiation 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 age

Mechanisms for Radiation Carcinogenesis  Ionizing radiation  Cell Death OR Cell Damage ↙ ↘ Repair Altered function

Psychosocial 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 workers

Nuclear Power and Radioactive Waste Disposal  types of Radioactive Waste Generated Annually; Fuel removed from commercial reactors Highly radioactive—from fuel processing, IONIC REACTORS Residues 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 site

High-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)