Radiation exposure (disaster)

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Background

General

- potentially easy to deal with since lots of people deal with radiation daily- univ, hosp, military

- easy to detect with geiger counters

- immediate effects well known and easy to assess with blood counts


Possible Scenarios

- we assume terrorists will only use one source of radiation at a time- combination sources unlikely

- synergism between radiation and chemicals unlikely- manage chemical exp first, radiation second

- only nuclear weapon will expose many people. all other types hard to expose many people

- small radiation dose do not affect people for many years


Dispersal of Radiation without use of Explosives

- minimally radioactive sources maybe used to create fear and panic- ex- exempt low level radioisotopes from nuc medicine, research. no immediate effects and probability of long term effects low

-highly radioactive substances- cobalt, cesium, iridium- used in radiotherapy and radiographic machines have penetrating radiation so easy to detect at check points

- if souce is metallic- there will be radiation exposure but no contamination. if powder get both exposure and contamination

- if handle it, will get local skin injury and are risk for acute radiation syndrome


Dispersal of Radiation with use of Conventional Explosives

- is greater concern since will be able to spread to more people and assoc traumatic injuries- will also cause additional fear, panic

- extent of dispersal depends on physical form of source- solid or powder, explosive type, atmospheric conditions

- health hazard only a few city blocks- goal of response to monitor and contain.


Nuclear Reactor Attack

- reactor if steel vessel in concrete building. if damaged, is designed to slow down stop reaction

- if cooling system damaged, may get some radiation leak- radioactive iodine and noble gases

- gas escape for reactor core will have immediate nearby health effects and rad iodine can have thyroid CA in kids long term at great diistances

- many nuclear engineering dept at univ have small reactors and are easy targets

- spent radioactive fuel rods stored in less secure places but hard to expose large population to this solid source


Nuclear Weapon Detonation

- unlikely use by terrorists since needs high level of expertise- but low yield weapon can be made or higher yield weapon could be stolen and used

- even if nuc weapon fizzled- will still be big blast

- destruction due to airblast and thermal radiation

- 1 psi increase breaks glass

- 12 psi 50% mortality

- fire ball -> flash/ flame burns, blindness

- inonizing radiation released in first minute as intense pulse- is initial radiation

- residual radiation, after first minute is fission and activation products

- ground burst causes radioactive soil into atmsphre and fallout of hundreds of miles- fallout can be lethal at greater ranges than at the blast or fireball


BASIC PRINCIPLES

Physical Properties

- gamma and xrays- deep penetration

- alpha- hazard only if ingested/ inoculated since penetration <0.1mm

- beta/ electrons- penetrate a few centimeters

- Rads- is dose absorbed by specific tissue. internation unit for absorbed dose is "gray" Gy. 1 gy = 100 rads

- different radioactive particles have diff effects at same absorbed dose- so use effective dose for comparison

- effective dose is "REM". 100 rem = 1 sievert

- one gray = one sievert when dealing with gamma and beta rays

- effect of radiation based on time of exp, distance and shielding

- dose decreases rapidly with square of distance and decreases on 1/9th if triple distance

- shield with lead or stay indoors

- radiation decays with time

- short lived- iodines

- long- cesium, stontium, cobalt

- rate of decay also effects dose of exposure and may effect management decisions


Biological Principles

- some cells may die but if cells role not critical for survival, may not see effect

- rapidly dividing cells- gi and bone marrow, most vulnerable

- dose <1gy, cells survive but get CA later

- radiation induced CA dose related

- leukemia within 2 yrs, solid tumors 5-10 or more yrs


Type of Radiation Exposure & ED Treatment

- can be localized or whole body, internal or external deposition and contamination

- mostly not emergency, just tx sxs and supportive care


Localized Exposure

- by direct handling. pt survives eventhough dose high since exposure drops rapidly with distance

- rad burn like thermal burn- but signs can occur after a few days, vasc insuff after several months and causing necrosis of previously healed skin

- tx c pain control, infc prophylaxsis, vasodilator tx, surg, skin graft,

- extent of penetration important factor in outcome

- beta rays from fallout only burn exposed skin


Whole Body Exp

- acute radiation syndrome- within 12 hrs, nv for 48 hrs

- dose >30 gy, CV and cns effects- hypotn, cerebral edema, sz, nv, ataxia, death

- dose 10- 30 gy, gi syndrome- nvd- then latent for 1 wk then recurrent nvd this time with sepsis and death

- hematopoetic syn- dose 2gy or higher- lymphocyte reduction within 48 hrs is indicator for rad exposure. get leukopenia and thrombocytopenia- bleeding and infc- may enhance recovery by hematopoetic factors

- cutaneous syn- damaged skin may interact with other organ damage

- amifostine- prophylactic radiation drug- causes hypotn as side effect unfortunately

- androstenediol- boosts immune system

- bone marrow xplant not helpful

- even if tx and survive hematopoetic syn, still die from radiation pneumonitis, denuded gi tract, hepatic and renal dysfunction


Internal Contamination

- may enter thru burns, wounds, inhale, ingest

- need to know type of radionuclide and chemical form

- need to tx quickly to be effective

- reduce absorption, dilute, blockage, displacement by non radioactive materials, mobilization, chelation

- potassium iodine for nuc weapon detonation or reactor breach- prevents radioiodine from accumulating in thyroid. take shortly after exp to be effective- if give too much get iodism

- dose- 130 mg adults, 65 mg 3- 18ys, 32 mg 1mo- 3yr, 16 mg for age< 1mo

- chelators- calcium, zinc, only for plutonium or americium


External Contamination

- clothes and exp skin- just clean up and prevent spread

- clean with soap and water

- if extremis- stabilize first, then decontam

- do not abraid skin while cleaning


Contaminated Burns and Wounds

- irrigate

- excise only if long acting radionuclides

- if whole body dose >1gy, close wound asap to prevent portal of infc

- in burns, radioactivity comes off with eschar and exudate


Disaster Management

- preparation, crisis management, consequences

- FBI is lead agency in terrorist incident

- during consequence management, FEMA fed emerg management agency takes over

- intervention- action to reduce exp and dose of radtn

- if dose 1 rem- stay in doors up to 2 days- evacuate for 1 wk if dose of 5 rem or more

- temp relocation if dose 3 rem in first month or 1 rem in subsequent month

- permanent resettlement if lifetime dose 100 rem

- pot iodine only if thyroid dose 100 mgy or more

- EMS occupational dose of 5 rem per yr dose not apply- allowable dose goes up for life saving event

- at dose of 0.1 gy/hr- ems may go in for short time but dose maybe life threatening


Early Management

- evacuate upwind if possible


Psychosocial Sxs

- insomnia, anxiety, impaired concentration, social withdrawal