Charles Miller: Hello I'm Charles Miller Chief of the Radiation Studies Branch Division of Environmental Hazards and Health Effects of the National Center for Environmental Health, Centers for Disease Control and Prevention. This following video is one of three videos designed to prepare health physicists, medical examiners, coroners and funeral directors to handle human remains contaminated with radioactive material. In this video you will learn the basic concepts of the internal and external radiation contamination and the hazards of working with contaminated human remains. Although CDC's guidelines are written for two specific scenarios: detonation of a nuclear weapon or of a radiological dispersal device. They are applicable in any situation where human remains are contaminated. These situations include the release of a body with radioactive implants or injections from a hospital, nuclear medicine department, an industrial accident, or a transportation accident.
Narrator: Before we examine scenarios let us review some basic concepts of radiation measurement. Radiation in this presentation refers to the charged particles or electromagnetic rays emitted from the nuclei of unstable atoms. Radiation is emitted by radioactive material. Contamination is the presence of radioactive material in a place where it is not wanted. Radiation dose is the amount of energy absorbed by human tissue, not the amount of radioactive material in the body. This dose can come from radioactive material, inside or outside the body. The dose rate is the amount of energy per unit time that is being absorbed by human tissue. Radiation dose has two effects: deterministic and stochastic. A deterministic effect is the presence of clinically observable symptoms including: hair loss, nausea, or reddening of the skin. The severity of a deterministic effect is proportional to the dose. As you will see in a table later in this video it takes a large radiation dose to cause a deterministic effect. A stochastic effect is a delayed effect that may or may not occur. For example: cancer. The risk of a stochastic effect is proportional to the dose, but the severity of the effect is independent of the dose.
This table from CDC's printed guidelines enables medical examiners, coroners and funeral directors to put doses into perspective. CDC's printed guidelines contain a copy of this table. CDC recommends printing and laminating this table for use in communicating with staff and the public. There are three forms of radioactive contamination the medical examiner, coroner, or funeral director may encounter: external contamination, internal contamination, or shrapnel. External contamination is dust or liquid on the clothing, skin or hair of a person. Ninety percent of external contamination can be eliminated by removing clothing. The rest can be eliminated by a vacuum cleaner, wet wipes, or washing. Internal contamination is radioactive material inside the body caused by inhalation, ingestion, or absorption through an open wound prior to death. Inhaled or ingested radioactive material initially resides in the lungs or GI tract. Slowly it is absorbed into the blood stream and transported to other organs or tissues. It is not possible to decontaminate a decedent with internal contamination. A decedent killed by the blast before having time to inhale, swallow, or absorb radioactive material will not have internal contamination. Shrapnel consists or small pieces of metal or ceramic embedded in the tissue. Shrapnel poses a greater threat to bystanders then any of the other forms of contamination. Shrapnel can be located with a radiation detector and surgically removed.
Now let us consider the differences between a nuclear weapon, a radiological dispersal device, and the nuclear medicine patient. When a nuclear weapon detonates fifty percent of the energy is released as a blast, thirty-five percent of the energy as heat, five percent of the energy as prompt radiation, and ten percent of the energy as radiation released over a period of time in fallout. The energy released in a nuclear weapon comes from the splitting of uranium or plutonium atoms by neutrons. Each split atom leaves two smaller radioactive atoms called fission products and it releases two or three neutrons to continue the reaction. Detonation of a nuclear weapon initially creates nine hundred different fission products. Most of them decay rapidly. At the end of the first hour there are one hundred sixty-five fission products remaining.
For the first two weeks after detonation the mix of fission products decays at the rate shown in this equation. This can be approximated by the rule of seven. Whenever the time since detonation increases by a factor of seven, the dose rate decreases by a factor of ten. Seven hours after detonation the dose rate has decreased to ten percent of its initial value. Two days or forty-nine hours after detonation the dose rate has decreased to one percent of its initial value. Two weeks after detonation the dose rate has decreased to one-tenth of one percent of its initial value. As you can see delaying mortuary operations after detonation of a nuclear weapon can significantly decrease exposure to radiation. After the detonation of a nuclear weapon many people near ground zero would die immediately from the heat or blast. Their bodies could have external, but not internal contamination. In the days that follow many people could die of injuries related to the detonation, to exposure to radioactive fall out, or to a combination of the two. Their bodies could have both external and internal contamination. Because everything inside the fireball is vaporized, radioactive shrapnel in the decedents bodies is very unlikely.
A radiological dispersal device is a device that spreads radioactive material. The material could be spread mechanically such as with a spray tank or by detonation of a conventional explosive. Since the perpetrator would have to steal or buy the radioactive material, build the device, transport it, and set it off, a radiation source with a long half life is required in the construction of a radiological dispersal device. Because of the long half-life there is no benefit to delaying operations after activation of a radiological dispersal device.
Hospitals frequently inject patients with radioactive material or implant radioactive seeds for diagnostic or therapeutic purposes. Although CDC's guidelines were written for terrorist events, the injected material can be considered internal contamination and the implanted seeds can be considered shrapnel. In CDC's guidelines it was necessary to balance the principles of radiation safety with the needs of medical examiners, coroners, funeral directors, and the public. The objectives of CDC's guidelines are as follows, listed in priority order: Under no circumstances should anyone receive enough radiation to cause a deterministic effect. Medical examiners, coroners, and their staff may receive some amount of radiation, in order to conduct an investigation to determine the cause and manner of death and allow for victim identification using scientific methods. Funeral directors may receive some amount of radiation in order to respect the cultural, emotional, or religious needs of bereaved family members. Family members or the clergy may receive some radiation exposure for the same reasons. Medical examiners may start operations even though delay would allow some decrease in radiation levels. Hospitals may release the body of a patient injected with radioactive material before the material has fully decayed. Decedents may be transported to a field morgue with radioactive material on their clothing to facilitate victim identification, but steps must be taken to avoid the uncontrolled spread of this contamination. Finally staff members should try and avoid any radiation exposure, unless there is some benefit from that exposure as described above.
ALARA is a well known acronym in the nuclear industry it stands for, as low as reasonably achievable. In the next two videos we will suggest ways to keep radiation doses as low as reasonably achievable while satisfying the other objectives.
For additional information visit CDC's website or call 1-800-CDC-INFO.
For a radiation emergency call the directors emergency operation center duty officer at 770-488-7100.
Charles Miller: Our next two videos will provide operational guidance for medical examiners, coroners, and funeral directors as well as some information for health physicists assisting in decedent operations. Thank you for your time.