“Radiation underground, and in the sky… Animals and birds that live nearby are dying” – “Mercy, Mercy Me” (The Ecology) lyrics sung by Marvin Gaye
Radiological events are not common occurrences, however, in recent years we have witnessed a major nuclear reactor accident in Fukushima, Japan which has unleased radionuclides into the environment, contaminating productive agricultural lands, and which still continues to leak millions of gallons of radioactive effluent into the sea, thus contaminating the marine food chain.
Islamic State (ISIS) jihadists, and other extremist groups, have vowed to construct and deploy Radiological Dispersal Devices (RDDs) or detonating an Improvised Nuclear Device (IND). The threat of global conflict escalating to the level of a global thermonuclear war is within the realm of stark and frightening possibility.
The legacy of a sentinel radiological event, Chernobyl, still haunts our memories of that fateful day, when the graphite reactor literally exploded, releasing millions of curies of radioactive material, after operators pushed the reactor to its limits during an experiment. The radioactive plume deposited radionuclides in the Ukraine, Russia, Northern Europe, and parts of North America due to atmospheric transport patterns.
The aftermath of Chernobyl, included mass casualties from high level radiation exposures, and the development of Acute Radiation Syndrome (ARS). Severe congenital deformities, and increased thyroid cancer and leukemias have been directly attributed to radiation exposure.
Most medical personnel, unless they are specifically trained in radiation medicine, eg. radiologists nuclear medicine physicians and technologists, possess very little knowledge or skill sets, if any, to effectively assess and treat radiation injuries.
Radiological releases can impact health care systems with irradiated and contaminated patients, posing unique challenges in triage, treatment, transport and mass decontamination of victims. The severity of radiological exposures are dose-dependent and can induce multi-systemic effects, thus engaging multidisciplinary health care teams comprised of various specialties and sub-specialties, such as hematology, emergency medicine, clinical toxicology, pathology, critical care medicine, infectious disease, trauma and burn surgery, plastic and reconstructive surgery, and, of course, radiology/nuclear medicine.
In addition, the expertise of nuclear, medical and health physics personnel, such as those from REAC/TS (Radiation Emergency Accident Center and Training Site) located in Oak Ridge, Tennessee, will also be involved in the medical and scientific response to a mass radiological exposure event. REAC/TS is one of the World Health Organization (WHO) –designated collaboration centers that would play an advisory and support role in a radiological event.
In a terrorism event, early radionuclide characterization will not be possible initially, as environmental sampling and radiochemical analyses will take some time. The initial protective countermeasures will be the use of Time x Distance x Shielding, appropriate and adequate personal protective equipment (PPE) for all first responders and health care personnel, establishing initial perimeters, and decontamination.
Establishing incident command, assessing, monitoring and mitigating hazards, maintaining situational awareness, performing search and rescue operations and critical life-saving interventions will be among the primary components of the overall response mission.
In any radiological release, the psychological “footprint” of the event could be even greater
than the physical impact of contamination, exposure, irradiation and radiation-induced illness.
Ionizing radiation brings a special “mystique” and is not well understood by most lay persons associating it with gross malformations and hideous, lingering deaths at any level of
exposure. In the context of a terrorist event, the psychological impact is even more acute and accentuated.
The inability to detect radiation with our biological senses, places many in a state of fear, uncertainty and utter panic, creating a high influx of “worried well” presenting at local hospitals and clinics, and contributing to an already strained health care system.
The complex injury matrix of a terrorist attack utilizing an RDD, for example, may include severe blast and thermal injuries, complicated by exposure to and contamination with an array of radionuclides. If indeed, sealed radioactive source(s) were strategically placed or isotopes were disseminated without an explosive device, victims would be presenting to urgent care clinics and emergency departments complaining of symptoms not immediately attributable to radiation exposure. In these times, radiation should be added to the differential diagnosis.
To better elucidate the pathophysiology of ARS, the concepts of cell death (apoptosis) and the LD 50 must be understood. Cell death is defined as the discontinuance of cell division and not killing the cell, per se. Significant doses of radiation can prevent cell division, whereas very high doses are required to actually kill the cell. Rapidly dividing cell populations such as the hematopoietic cell lines of the bone marrow, the epithelial lining of the gastrointestinal system and fetal cells are extremely sensitive to ionizing radiation. The LD50 is the lethal dose required to kill one-half of animal test models, a very common factor in the annals of toxicology and radiobiology. The dose required varies among animal species, and according to co-factors such as age, sex, genetic considerations, pre-existing co-morbidities and nutritional status. With respect to humans, much of our data on radiation effects have been gathered from radiation accidents, such as the Chernobyl reactor accident, Fukushima release, the inadvertent exposures due to a discarded radiotherapy device in Goiania, Brazil, and the atomic bombings of Hiroshima and Nagasaki. The LD50 for humans is believed to be in the realm of 2.5 – 4.5 Gys (250-450 rads).
The induction of ARS is based on the existence of certain parameters. Considered to be of high importance is the presence of a high dose delivered at a very high dose rate. Also the radiation must be either gamma or neutron radiation capable of deeply penetrating living tissues. ARS can be divided into four phases: a) prodromal phase, b) the latent phase, c) the illness phase, d) the phase of final outcome, i.e. recovery or death.
The onset of symptoms can be minutes to hours, which is dose-dependent. The most important indicator of prognosis is the time of onset vomiting following irradiation. Emesis (vomiting) within 2-4 hours is ominous, and indicates a high dose of radiation has been received. A fall in lymphocyte count is also an indicator of severity of exposure by extrapolating the Andrews lymphocyte curve. The key parameter to monitor post –exposure is the white cell differential.
While we cannot possibly display the full complexity and medical management of radiation casualties here, we can mention basic management principles and available therapeutic modalities. First, Airway, Breathing, Circulation, Disability (assessing function) and Exposure, i.e. minimizing additional exposure and exposing injured areas) of primary importance. Life-saving interventions such as correcting airway compromise hemorrhage control treating shock and, including damage –control surgery must never be delayed.
Treatments such as antimicrobials, antifungals, and antivirals must be available to combat opportunistic infections due to defective immunocompetence, and to treat cases of overwhelming sepsis. Blood transfusions may become of paramount importance, both because of traumatic injuries and the hematopoietic effects of ionizing radiation. The stimulation of bone marrow by cytokines such as colony-stimulating factor (CSF), such as filgastim or bone marrow transplantation may be considered. The internal deposition of radionuclides will require de-corporation agents (chelators) to assist in eliminating these agents from organs. Cytogenetic testing may be required to determine chromosomal aberrations, ie. dicentric malformations.
The use of nuclear technology in power production and other industrial, research and medical uses must always be balanced in terms of risk vs. benefit. In addition, the ready availability of radioactive materials, smuggling and production of weapons-grade materials by rouge nation – states, and the increasing sophistication of terrorist factions, such as ISIS are all reasons to enhance the readiness of health care systems and public health infrastructure.