Radiation exposure (disaster)

Background

  • “Ionizing” radiation is electromagnetic or particulate which can create charged particles or ions
  • "Non-ionizing radiation" ( e.g., light, microwaves, and radiowaves) does not have sufficient energy to eject an electron from another atom
  • Ionization of biologically important molecules, e.g., DNA, can cause cellular death
  • Ionizing radiation at higher doses can cause damage to actively dividing and undifferentiated cell types, e.g., stem and progenitor cells in the bone marrow, gastrointestinal system, and skin

Radiological and Nuclear Scenarios of Concerns

  • Radiological exposure devices
  • Radiological dispersal devices
  • Nuclear power plant incidents/accidents
  • Improvised nuclear devices

Radiological Exposure Devices (RED)

  • A RED is a device that can cause exposure to ionizing radiation without the knowledge of the person being exposed
  • Surreptitious placement of a RED could delay discovery and notification of the healthcare community
  • Injury is based on the radiation dose received, whether accidental or intentional in nature
  • A concealed RED scenario could result in serious injuries

Radiological Dispersal Devices (RDD)

A RDD is any device that is used to spread radioactive materials. More commonly thought of as an explosive device or “dirty bomb,” RDDs do not necessarily need to explode in order to spread radiological material into the environment. A non-explosive RDD could cause environmental contamination that could lead to human contamination. Examples may include the use of facility ventilation systems, fumigation systems, etc. Improvised explosive devices (IEDs) are detonated almost every day in Iraq and Afghanistan and cause numerous deaths and disfigurements due to physical trauma. The explosion of a device with radioactive materials could cause additional injury, internal contamination, and panic. Persons near the epicenter of an explosion of a dirty bomb will sustain physical trauma, thermal burns, and embedded foreign bodies including radioactive shrapnel.

The amount of physical damage from a RDD would depend upon the amount and type of explosives used. The additional radiological consequences would depend upon the radiological source and the physical properties as well as the explosive device. Removal of foreign bodies would require that healthcare providers wear appropriate personal protective equipment (PPE) and have access to radiation monitoring equipment, including ring dosimeters for physicians who have to remove radioactive shrapnel. Management of internal contamination by inhalation or via wounds might be required for some of the casualties.

Nuclear Power Plant (NPP) Incident/Accident

The Fukushima Japan nuclear power plant disaster in March of 2011 was highly unusual and the first time that such a serious situation at a nuclear power plant resulted from an environmental disaster.6 The Pacific Ocean earthquake caused a 13-15 meter tsunami to hit the shore of Japan at the site of the nuclear power plant (NPP) at Fukushima. Thousands of people were evacuated because of radiological concerns associated with the crippled power plant. Predictably, radioactive materials released from the damaged reactor(s) received much hype in the media and heightened public concern about exposure to radioactive contamination. Emphasizing the public’s preoccupation with radiation-related consequences, the radiological concerns overshadowed the deaths and the displacement of tens of thousands of people from the effects of the tsunami.

Nuclear power plants use the energy created by the fissioning of atomic nuclei — often referred to as the” splitting of the atom” — to generate electricity. In nuclear power the heat generated during the fission process converts water to steam, which is then used to drive electricity-generating turbines. Water is continually circulated through the reactor core via coolant pumps to control temperatures. The loss of power to coolant pumps or other interruptions of cooling capabilities to the reactors, can allow the reactor core to overheat. This is known as a loss-of-coolant-accident (LOCA). Without the ability to cool the reactors, the radioactive core can begin to melt, hence the term “melt-down.”

Nuclear Device Detonation

  • 3 forms of energy released by nuclear detonation[1]
    • Heat (35% of total)
    • Shock or bomb blast (50%)
    • Radiation (15%)

It was not until 2004 that the U.S. government published the National Response Plan (NRP), now called the National Response Framework8 that outlined the federal response to national-level incidents. In 2005, 15 all-hazards national planning scenarios were developed for incident specific response planning. The first of these scenarios describes a 10 kiloton (10 kT) improvised nuclear device (IND) detonation. In response to this scenario, the Federal Emergency Management Agency (FEMA) began to plan and prepare for response to a detonation of an IND. Effective response and recovery actions following the detonation of a small nuclear weapon are thought to be entirely feasible thorough implementation of the National Incident Management System (NIMS) and the incident command system (ICS).

The detonation of any kind or size of nuclear weapon would be expected to cause massive physical damage to a community and untold psychological devastation to its population. In 2009, the National Security Staff released the first edition of Planning Guidance for the Response to a Nuclear Detonation10 In this document, planners categorized the devastation, types of physical damage, and types of human injuries based upon distance from the detonation epicenter in zones. The second edition of this document, released in June 2010, updated recommendations and guidance based on intensive modeling efforts to try to further quantify the effects of a nuclear detonation in an urban American city. Part of the updates to the guidance includes further refinement of the proposed damage zones. The document’s authors called the area closest to the epicenter the Severe Damage (SD) zone; the adjacent area the Moderate Damage (MD) zone; and the affected area furthest away from the epicenter, the Light Damage (LD) zone. In addition, a dangerous fallout (DF) radiation zone, which is determined by the scattering of radiological material, is also defined3. The presumed “safe” and “dangerous” distances away from the epicenter vary from scenario to scenario in modeling efforts and would be made after-the-fact by the incident commander based upon types of damage found on the ground. Zone determinations would depend upon:

  • The yield of the weapon
  • Whether the detonation was at a height or at ground level, and
  • The topographical features of the terrain and its structures.

Basic Principles

Physical Properties

  • Radiation Types
    • Gamma and xrays - deep penetration
    • Alpha - hazard only if ingested/ inoculated since penetration only ~0.1mm
    • Beta/electrons - penetrate only a few centimeters
  • Dose
    • Rads - dose absorbed by specific tissue.
    • Gray (Gy) - international unit for absorbed dose. (1 Gy = 100 rads)
    • REM - "Effective Dose" (100 rem = 1 sievert = 1 Gy)
  • Principles of exposure
    • Different radioactive particles have diff effects at same absorbed dose- so use effective dose for comparison
    • 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
    • Lead is an effective shield
  • Radiation decays with time
    • Iodine isotopes are short lived
    • Cesium, stontium, cobalt are longer-lived
    • 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 (e.g. GI and bone marrow) are most vulnerable
  • Dose ~1Gy, cells survive but get cancer later
  • Radiation-induced cancer dose related
  • Leukemia within 2 yrs, solid tumors 5-10 or more yrs

Differential Diagnosis

Mass casualty incident

Evaluation

  • Evaluate and stabilize any life threatening physical injuries (ABC's)
  • Decontaminate after stabilized
  • Check for external contamination - document location, dose rate and/or count measurements initial and after decontamination. Document description of decontamination methods and agents used
  • Check for internal contamination - swab both nostrils, collect 24-hour stool and 24-hour urine samples. Identify radionuclide (chemical form), solubility and particle character. Document suspected route of contamination.
  • Treat wounds symptomatically and close wounds within 35-48 hours
  • Obtain baseline serum amylase, complete blood count (CBC) then repeat CBC every 6-8 hours for 2-3 days. Collect second serum amylase at 24 hours post-exposure
  • External exposure to ionizing radiation - document location and position of patient relative to source of radiation at time of exposure. Document time and duration of exposure. Was dosimeter being worn? If so type and where on patient's body? Was dosimeter collected? By whom? Were is dosimeter now?

Management

  • Can be localized or whole body, internal or external deposition and contamination
  • Mostly not emergency, just treatment symptoms and supportive care
  • Consider contacting health physicist and/or radiation safety officer for help

Localized Exposure

  • By direct handling. patient survives even though dose high since exposure drops rapidly with distance
  • Radiation burn like thermal burn- but signs can occur after a few days, vascular insufficiency after several months and causing necrosis of previously healed skin
  • Treatment with pain control, infection prophylaxsis, vasodilator treatment, surgery, skin graft,
  • Extent of penetration important factor in outcome
  • Beta rays from fallout only burn exposed skin

Whole Body Exposure

Those persons who receive a significant exposure from radiation may experience acute radiation syndrome (ARS), a systemic illness caused by exposure to a level of ionizing radiation sufficient to cause damage to the hematopoietic, gastrointestinal, cardiovascular or central nervous system

Dose SubSyndrome Potential Signs and Symptoms
N/A Subclinical
1 GY (100 rad) Hematopoietic Lymphocytopenia – 24-48 hours

(worsens with increasing dose) Thrombocytopenia, Anemia - weeks

6 Gy (600 rad) Gastrointestinal Nausea/vomiting, diarrhea with resulting hypovolemia and electrolyte shifts,
10 Gy (1000 rad) Neurovascular Nausea, headache, lethargy, ataxia, confusion, seizures
    • Within 12hr, nausea/vomiting for 48hr
    • Dose >30 gy: cardiovascular and CNS effects - hypotension, cerebral edema, seizure, nausea/vomiting/diarrhea, ataxia, death
    • Dose 10-30 gy: GI syndrome: nausea and vomiting/D, then latent for 1 wk, then recurrent nausea and vomiting/d this time with sepsis and death
  • Hematopoetic symptoms- dose 2gy or higher- lymphocyte reduction within 48 hrs is indicator for rad exposure. get leukopenia and thrombocytopenia- bleeding and infection- may enhance recovery by hematopoetic factors
  • Cutaneous symptoms- damaged skin may interact with other organ damage
  • Amifostine- prophylactic radiation drug- causes hypotension as side effect
  • Androstenediol- boosts immune system
  • Bone marrow transplant not helpful
  • Even if treatment and survive hematopoetic symptoms, 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 treatment quickly to be effective
  • Reduce absorption, dilute, blockage, displacement by nonradioactive 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- 130mg adults, 65mg 3- 18ys, 32mg 1mo- 3yr, 16mg 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 exposure and dose of radiation
  • If dose 1 rem- stay in doors up to 2 days- evacuate for 1 wk if dose of 5 rem or more
  • Temperature relocation if dose 3 rem in first month or 1 rem in subsequent month
  • Permanent resettlement if lifetime dose 100 rem
  • Potassium iodine only if thyroid dose 100mgy or more
  • EMS occupational dose of 5 rem per yr dose not apply- allowable dose goes up for lifesaving event
  • At dose of 0.1 gy/hr- ems may go in for short time but dose may be life threatening

See Also

References

  1. Waselenko JK, MacVittie TJ, Blakely WF, et al. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med. 2004 Jun 15;140(12):1037-51.