APPENDIX A

MEDICAL EFFECTS OF NUCLEAR, BIOLOGICAL, AND CHEMICAL WEAPONS AND TOXIC INDUSTRIAL MATERIAL

A-1. General

A-2. Physical Effects of Nuclear Weapons

a. The principal physical effects of nuclear weapons are blast, thermal radiation (heat), and nuclear radiation. These effects are dependent upon the yield (or size) of the weapon expressed in kilotons (KT), the physical design of the weapon (such as conventional and enhanced), and the method of employment. The distribution of energy (Figure A-1) from the detonation of a moderate-sized (3 to 10 KT) weapon is as follows:

(1) Fifty percent as blast.

(2) Thirty-five percent as thermal radiation; made up of a wide spectrum of electromagnetic radiation, including infrared, visible, and ultraviolet light and some soft x-ray radiation.

(3) Fourteen percent as nuclear radiation, 4 percent as initial ionizing radiation composed of neutrons and gamma rays emitted within the first minute after detonation, and 10 percent as residual nuclear radiation (fallout).

(4) One percent as EMP.

b. Larger weapons are more destructive than smaller weapons, but the destructive effect is not linear. Table A-1 presents a comparison of three aspects of nuclear weapons effects with yield.

Figure A-1. Distribution of energy.

(2) A surface burst is a detonation in which the fireball actually touches and vaporizes the land or water surface. In this case, the area affected by blast, thermal radiation, and initial nuclear radiation will be smaller than for an airburst of comparable yield. However, in the region around ground zero, the destruction will be much greater and a crater is often produced. Additionally, all the material that was within the fireball becomes fallout and will be a hazard downwind. A surface burst is the most likely type of terrorist detonation.

(3) A subsurface burst is an explosion in which the detonation is below the surface of land or water. Cratering usually results. If the burst does not penetrate the surface, the only hazard is from the ground or water shock. If the burst penetrates the surface, blast, thermal, and initial nuclear radiation will be present, though less than for a surface burst of comparable yield. Local fallout will be heavy over a small area.

(4) A high altitude burst occurs above 30,000 meters. Radiation and physical effects do not reach the ground and there is no local fallout. This is the only detonation where the effects of the EMP are significant. Nonhardened electronic equipment including many medical devices may become inoperative. The EMP damage is a moot point with other types of detonations, as its range is primarily limited to the area of intense physical destruction.

Table A-1. Comparison of Weapons Effects (Radii of Effects in Kilometers—Airburst)

A-3. Physiological Effects of Nuclear Weapons

a. The rapid compression and decompression of blast waves on the human body results in transmission of pressure waves through the tissues. Resulting damage is primarily at junctions between tissues of different densities (bone and muscle), or at the interface between tissue and airspace. Lung tissue and the gastrointestinal system (both contain air) are particularly susceptible to injury. The tissue disruptions can lead to severe hemorrhage or to an air embolism; either can be rapidly fatal. Direct overpressure effects do not extend out as far from the point of detonation as the drag force and are often masked by the drag force effects. A typical range of probability of lethality, with variations in overpressure for a 1 KT weapon, is shown in Table A-2.

Table A-2. Range of Lethality of Peak Overpressure

(2) Overpressure lower than those in Table A-2 can cause nonlethal injuries such as lung damage and eardrum rupture. Lung damage is a relatively serious injury, usually requiring hospitalization, even if not fatal; whereas eardrum rupture is a minor injury, often requiring no treatment at all.

(a) The threshold level of overpressure for an unreinforced unreflected blast wave that can cause lung-damage is about 1.0 atmosphere.

(b) The threshold level for eardrum rupture is around 0.2 atmospheres; the overpressure associated with a 50 percent probability of eardrum rupture is about 1.1 atmospheres.

(3) Casualties requiring medical treatment from direct blast effects are produced by overpressure between 1.0 and 3.5 atmospheres. However, other effects (such as indirect blast injuries and thermal injuries) are so predominate that patients with only direct blast injuries make up a small part of the patient workload.

b. The drag forces (indirect blast) of the blast winds are proportional to the velocities and duration of the winds. The winds are relatively short in duration, but can reach velocities of several hundred km per hour. Injury can result from missiles impacting on the body or from the physical displacement of the body against objects and structures.

(1) The distance from the point of detonation at which severe indirect injury occurs is greater than that for equally serious direct blast injuries. A high probability of serious indirect injury can occur when the peak overpressure is about 0.2 atmospheres. This range will increase with the increased size of the weapon; for a 1 KT weapon, the range is 0.22 km, whereas for a 20 KT weapon, the range is 0.76 km. At greater ranges injuries will occur and casualties will be generated, but not consistently.

(2) The drag forces of the blast winds produced by a nuclear detonation are so great that almost any form of vegetation or structure will be broken up or fragmented into missiles. Thus, multiple, varied missile injuries will be common, increasing their overall severity and significance. Table A-3 lists ranges at which significant missile injuries can be expected.

Table A-3. Ranges for Probabilities of Serious Injury from Small Missiles

(3) The velocity to which missiles are accelerated is the major factor in causing injury. The probability of a penetration injury increases with increasing velocity, particularly for small, sharp missiles such as glass fragments. Small, light objects are accelerated to speeds approaching the maximum (wind) velocity. Table A-4 shows data for probability of penetration related to size and velocity of glass fragments.

Table A-4. Probability of Glass Fragments Penetrating the Abdominal Cavity

(4) Heavy, blunt missiles may not penetrate, but can result in significant injury, particularly fractures. The threshold velocity for skull fractures from a 4.5 milligram (mg) missile is about 4.6 meters per second (m/sec).

(5) The drag forces of the blast winds are strong enough to displace large objects (such as vehicles), or cause large structures to collapse (such as buildings) resulting in serious crushing injuries. Man himself can become a missile resulting in injuries (called translational injuries). The velocity at which the body is displaced will determine the probability and the severity of injury. Assuming a displacement of 3.0 meters, the impact velocity associated with various degrees of injury is shown in Table A-5. The velocities in Table A-5 can be correlated against yield. The ranges at which such velocities can occur and the probability of injury are given in Table A-6.

Table A-5. Translational Injuries

Table A-6. Ranges for Selected Impact Velocities of a 70-Kilogram Human Body Displaced by Blast Wind Drag Forces for Different Yield Weapons

A-4. Biological Effects of Thermal Radiation

a. Thermal radiation travels outward from the fireball in a straight line; therefore, the amount of energy available to cause flash burns decreases rapidly with distance. Close to the fireball all objects will be incinerated. The range for 100 percent lethality will vary with yield, height of burst, weather, environment, and immediacy of treatment. The critical factors determining the degree of burn injury are the flux (calories per square centimeter/second [cal/cm²/sec]) and the duration of the thermal pulse. The total amount of thermal radiation needed to cause a flash partial thickness burn on exposed skin will vary with the yield of the weapon and the nature of the pulse (Table A-7). Most burn patients will come from the zones where partial thickness burns occur. In areas where radiation, blast, and thermal intensity are highest, burn victims surviving long enough to reach medical care will be rare.

Table A-7. Factors for Determining the Probability of Partial Thickness Burns

b. Indirect (flame) burns result from exposure to fires caused by the thermal effects in the environment, particularly from ignition of clothing. The larger-yield weapons are more likely to cause firestorms over extensive areas. There are too many variables in the environment to predict either incidence or severity of casualties. Expect the burns to be far less uniform (in degree) and not limited to exposed surfaces. For example, the respiratory system may be exposed to the effects of hot gases produced by extensive fires. Respiratory system burns cause high morbidity and high mortality rates.

c. The initial pulse of radiation in the optical and thermal bands can cause injuries in the forms of flash blindness and retinal scarring. The initial brilliant flash of light produced by the nuclear detonation causes flash blindness. This flash swamps the retina, bleaching out the visual pigments and producing temporary blindness. During daylight hours, this temporary effect may last for about 2 minutes. At night, with the pupil dilated for dark adaptation, flash blindness will affect personnel at greater ranges and for greater durations. Partial recovery can be expected in 3 to 10 minutes, though it may require 15 to 35 minutes for full night adaptation recovery. Retinal scarring is the permanent damage from a retinal burn. It will occur only when the fireball is actually in the individual's field of view and should be a relatively uncommon injury. The location of the scar will determine the degree of interference with vision. Because night vision apparatus electronically amplifies an image, it cannot transmit the flash intensity and will not cause eye injury.

A-5. Physiological Effects of Ionizing Radiation

A nuclear burst results in four types of ionizing radiation: neutrons, gamma rays, beta, and alpha radiation. The initial burst is characterized by neutrons and gamma rays while the residual radiation is primarily alpha, beta, and gamma rays. The effect of radiation on a living organism varies greatly by the type of radiation to which the organism is exposed. See Table A-8 for characteristics of nuclear radiation.

a. Alpha particles are extremely massive, charged particles (four times the mass of a neutron); they are a fallout hazard. Because of their size, alpha particles cannot travel far and are fully stopped by the dead layers of the skin or by the uniform. Alpha particles are a negligible external hazard, but if inhaled or ingested, can cause significant internal damage.

Figure A-2. Threshold distance for minimal chorioretinal burn and flash blindness versus yield (airburst) at night.

Table A-8. Characteristics of Nuclear Radiation

f. The most radiosensitive organ systems in the body are the male reproductive, the hematopoietic, and the gastrointestinal systems. The relative sensitivity of an organ to direct radiation injury depends upon its component tissue sensitivities. Cellular effects of radiation, whether due to direct or indirect damage, are basically the same for the different kinds and doses of radiation. The simplest effect is cell death. With this effect, the cell is no longer present to reproduce and perform its primary function. Changes in cellular function can occur at lower radiation doses than those that cause cell death. Changes can include delays in phases of the mitotic cycle, disrupted cell growth, permeability changes, and changes in motility. In general, actively dividing cells are most sensitive to radiation. Additionally, radiosensitivity tends to vary inversely with the degree of differentiation of the cell.

g. Predicting radiation effects is difficult because often it is unknown which organs were exposed. Thus, most predictions are based on whole body irradiation. Partial body and specific organ irradiation will occur due to shielding by equipment, from fallout particles, or from internal deposition. Depending upon the organ system, the irradiation can be severe. The severe radiation sickness resulting from external, whole body irradiation and its consequent organ effects is a primary medical concern. The median lethal dose (LD) of radiation that will kill 50 percent of the exposed persons within a period of 60 days (designated as LD50/60) is estimated to be approximately 4.5 gray (Gy) if appropriate medical care is not provided to the casualties. Medical intervention should raise this figure to approximately 10 Gy. This larger figure includes most of the casualties who would be actually capable of reaching medical care following a nuclear detonation, and nearly all those who could be exposed to a RDD. For acute effects of single high dose rate exposures of whole-body irradiation to healthy adults see Table A-9.

h. Recovery of a particular cell system will occur if a sufficient fraction of a given stem cell population remains after radiation injury and appropriate stimulation and protection are received. Complete recovery may appear to occur; however, the immune system may repair incompletely with consequent greater susceptibility to future insult from a variety of agents. It is possible for late somatic effects to have a higher probability of occurring because of the radiation damage. Efficacy of both prior and future immunization in this group is not adequately understood.

i. Interactions between radiological injury and chemical or biological agents appear to be synergistic. Insult by these agents in radiologically injured personnel, even in individually subclinical dosages, may result in significant clinical illness.

A-6. Handling and Managing Radiologically Contaminated Patients

b. Handling Radiologically Contaminated Patients. To properly handle radiologically contaminated personnel, medical personnel must first detect the contamination. Detectors that may be used are the AN/PDR27 and AN/VDR2 to monitor patients for contamination. Generally, a reading on the meter twice the current background reading indicates that the patient is contaminated. Monitoring is conducted when potentially contaminated personnel arrive at the MTF. This monitoring is conducted at the MTF's receiving point before admitting the patient. Contaminated patients must be decontaminated before admission. Removal of radiological contamination is less important than immediate lifesaving treatment and providing the best possible medical care. Lifesaving care before decontamination is provided outside the MTF.

c. Decontamination. Removing all outer clothing and a brief washing or brushing of exposed skin will reduce 95 percent of contamination; vigorous bathing or showering is unnecessary. See Appendix G for patient decontamination procedures.

d. Internal Contamination. Internalization of radioactive isotopes will primarily occur via inhalation, ingestion, and contaminated wounds. Extensive internal decontamination should only be undertaken when individual dose estimates indicate that the individual will benefit from the procedures. Soldiers who wear their protective mask will be adequately protected from inhalation and ingestion of radioactive particulate matter. Internal contamination is considered a delayed problem and does not influence triage categories, as does irradiation injury.

e. Treatment. Treatment procedures for radiation injuries are described in FM 4-02.283, FM 8-9, and the NATO Handbook, Emergency War Surgery. Appropriate medical intervention and bone marrow resuscitation will prevent most deaths secondary to irradiation and infection.

Table A-9. Acute Clinical Effects of Single High Dose Rate Exposures of Whole-body Irradiation of Healthy Adults

A-7. Radiological Patients in Stability Operations and Support Operations

In stability operations and support operations, high levels of environmental contamination and the use of RDD can cause radiological injury to personnel at levels below that necessary to produce performance decrement and traditional casualty status. Treatment and evacuation guidelines will be in accordance with command guidance. Individual physical dosimetry is the most expedient measurement technique for this exposure (see Table A-10). These radiation injuries and effects may also be seen in war; especially, from hostile forces employment of RDDs.

Table A-10. Stability Operations and Support Operations: Radiation Injuries and Effects of Radiation Exposure of Personnel