Q&A with a leading radiation exposure expert
Given the much discussed "dirty bomb" scenario of using a conventional explosive to disperse radioactive material, it is reassuring to know that no U.S. health care worker has ever been harmfully exposed by a patient following a radiation incident.
That and a few other salient points were recently stressed to Bioterrorism Watch during an interview with Robert C. Ricks, PhD, director of the Radiation Emergency Assistance Center/ Training Site (REACT/S) in Oak Ridge, TN. The center’s web site (http://www.orau.gov/reacts/emergency.htm) has a wealth of information on triaging and treating potentially contaminated patients in the wake of a nuclear incident.
Q. What is the threat to health care workers treating victims of a nuclear attack? Is it primarily surface skin contamination as opposed to any inhalation threat?
A. In the United States, no health care worker responding to a contamination accident has ever received a medically significant exposure. No health care provider has experienced significant contamination if they utilize those measures commonly used in hospitals for infection control. This is normally referred to as universal (standard) precautions. The primary concern is contamination of the skin, while inhalation threats are minimal if health care providers follow simple guidelines to prevent resuspension of contaminants into the air.
Q. Should any medications be taken as prophylaxis for workers exposed to contaminated patients?
Q. Regarding the hospital emergency department response to victims, what are a few of the most important measures to determine the radiological status of patients?
A. Unlike most hazardous materials a general-purpose radiation survey instrument (GM Count Rate Meter with pancake probe) can be used to detect the presence of alpha, beta, and gamma radiations. Any hospital with a nuclear medicine department would have such instruments and individuals trained in their use. Otherwise, these instruments can be obtained from state and local radiation health officials or your local hazardous materials unit of the fire department. Therefore, one should be able to triage the exposed vs. contaminated patient. If a dirty bomb is suspected, all victims should be presumed contaminated until proven otherwise.
Q. The isolation protective measures described on the REACT/S web site use protective equipment that is generally available at most hospitals, but what about the recommendation that "a radiation dosimeter should be assigned to each team member and attached to the outside of the surgical gown at the neck where it can be easily removed and read?" Should hospitals have these available now?
A. A dosimeter is used to determine the cumulative exposure over time while working in a contaminated environment. If dosimeters are available, health care professionals can check their exposure levels at periodic intervals. In the absence of personal dosimeters, health care providers may have to rely on the results of radiological monitoring in their immediate work area. The hospital radiation safety officer is the best resource person in this regard.
Q. Are patients exposed to a dispersed cloud in a dirty bomb scenario likely to have internal contamination and/or develop potentially lethal acute radiation syndrome?
A. Individuals in locations where radioactive materials are dispersed into the environment are likely to be contaminated both externally and internally. It is very doubtful that these individuals will develop acute radiation syndrome.
Q. Is there a type of nuclear material that is more likely than others to be used in a dirty bomb scenario?
A. While a variety of potential radiation materials exist for making dirty bombs, these four are more likely due to their widespread use on a worldwide basis: cesium 137, cobalt 60, iridium 192, americium 241.
Protective clothing: The purpose of protective clothing is to keep bare skin and personal clothing free of contaminants. Members of the radiological emergency response teams should dress in surgical clothing (scrub suit, gown, mask, cap, eye protection, and gloves). Waterproof shoe covers also should be used. All open seams and cuffs should be taped using masking or adhesive tape. Fold-over tabs at the end of each taped area will aid removal. Two pairs of surgical gloves should be worn. The first pair of gloves should be under the arm cuff and secured by tape.
The second pair of gloves should be easily removable and replaced if they become contaminated. A radiation dosimeter should be assigned to each team member and attached to the outside of the surgical gown at the neck where it can be easily removed and read.
If available, a film badge or other type of dosimeter can be worn under the surgical gown. A waterproof apron also can be worn by any member of the team using liquids for decontamination purposes. This protective clothing is effective in stopping alpha and some beta particles but not gamma rays. Lead aprons, such as those used in the X-ray department, are not recommended since they give a false sense of security — they will not stop most gamma rays.
Treatment area: If possible, select a treatment room near an outside entrance. Clear the area of visitors and patients. Remove or cover equipment that will not be needed during emergency care of the radiation accident victim. Several large plastic-lined waste containers will be needed. The treatment table should be covered with several layers of waterproof, disposable sheeting. Plastic bags in all sizes will be needed and should be readily available. Survey instruments should be checked and ready for use before the patient arrives. Background radiation levels should be documented. The treatment team should be prepared to meet the patient at the ambulance where the patient can be transferred to the prepared treatment gurney. Rolls of brown wrapping paper or butcher paper 3-4 feet wide can be unrolled to make a path from the ambulance entrance to the decontamination room.
Triage: During triage, consideration is given to both medical and radiological problems. Serious medical problems always have priority over radiological concerns, and immediate attention is directed to life-threatening problems. Radiation injury rarely causes unconsciousness or immediate visible signs of injury and is not immediately life-threatening; therefore, other causes of injury or illness must be considered. Noncontaminated patients are admitted to the usual treatment area. Contaminated patients are admitted to a specially prepared area. When in doubt, a critically injured patient should be taken immediately into the prepared area. If the victim’s condition allows, an initial, brief radiological survey can be performed to determine if the victim is contaminated. Any radiation survey meter reading above background radiation levels indicates the possibility of contamination. A more thorough survey will be performed once life-threatening problems are addressed.
The victim’s contaminated clothing should be removed before arrival at the hospital (at accident scene), if this can be accomplished without causing harm or delay. Otherwise, clothing should be removed as promptly as possible (without compromising life or limb), using care to avoid spread of any contaminants embedded in or on the clothing. Clothing and any accompanying sheets, blankets, etc. should be placed in a plastic bag. Caregivers should change gloves after handling clothing or other potentially contaminated items.