Radiation exposure (disaster)

Background

  • 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

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

  1. irrigate
  2. excise only if long acting radionuclides
  3. if whole body dose >1gy, close wound asap to prevent portal of infc
  4. 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