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