Each mission and deployment scenario presents its own set of risks and hazards, not all of which are predictable. Certain missions may present with more obvious hazards (such as combat deployment). However, peacekeeping, humanitarian, training, and stabilization and/or rebuilding missions each may pose unique hazards.
One of the major challenges to military occupational health is that to a large degree, specific hazards and health issues during mobilization and deployment are inevitable because their occurrence cannot be avoided. Also, optimal exposure prevention tactics (removal from the area) cannot always be practiced and the continual weighing of the threats from multiple combinations of risks on human health and lives necessitates trade-offs in terms of focusing on the more adverse medical threats. The goal of military operational research efforts is to better understand these risks (alone or in combinations) to enable better preparation for and prevention of these risks and to develop and test proactive protection procedures.
Within the U.S. military, particularly since the 1991 Persian Gulf War, risk management system processes have been continually tested and reworked to best provide commanders with methods to evaluate and act on risks presented by operational hazards during deployment or specific missions (including a framework for management of occupational and environmental hazards). The operational risk management system outlines a process for identifying, assessing, and controlling risks, and includes a mechanism of evaluating the effectiveness of the control measures put in place.
In general, preventive medicine personnel are responsible for carrying out the process of identifying the occupational and environmental hazards, assessing the level of medical or health threat associated with the hazards, characterizing the associated risks of the threat(s) and the proposed control action(s), and then transmitting the risk assessment information and recommended control measure options to the commander. Preventive medicine personnel also are instrumental in implementing the control action(s) decided upon by the commander, evaluating the effectiveness of the action in controlling the threat(s), and documenting follow-up reassessments of the action and lessons learned for future deployments.
Within the U.S. military’s hierarchy of occupational and environmental chemical hazards, those that contribute to health and medical threats require evaluation (TG230, 2003: 18–23), but by definition, they may represent different levels of importance to the military operation at hand. A health threat is one that can cause negative health effects to the individual serviceman or woman. For example, hereditary conditions that present in adulthood, individual exposure to industrial chemicals, other injuries or conditions, or physical and psychological traumas that affect an individual but not the whole unit are considered health threats. Medical threats are more severe and have the potential to adversely affect unit or mission accomplishment or effectiveness. In the broadest sense, medical threats include all ongoing potential enemy actions, environmental conditions, disease conditions, and nonbattle injuries that degrade unit effectiveness. Military exposure guidelines and an outline of the U.S. Armed Forces approach to operational risk management are given in several technical guides (TG 230, 2003; TG 248, 2001). Applying a risk matrix, which evaluates the probability of exposure combined with the hazard severity ranking, provides an estimate of the risk level associated with the hazard of concern.
Exposure to occupational and environmental hazards during deployment situations may be transient or of limited duration but might be present at very high levels that could impact individual health and/or the mission. Other scenarios may involve lower levels of exposure but be continuous and possibly put military personnel at higher risk for possibly delayed or longer-term health problems. Thus, the frequency, intensity, and duration of the exposure(s) are evaluated when estimating the level of risk. Environmental monitoring results from the deployment area of operation are used to make the determination of the hazard severity by making a comparison of the detected military exposure levels to guidelines and standards (e.g., TG 230, 2003; TG230D, 2003; TG 248, 2001).
Occupational And Environmental Health Hazards
There are three classes of military occupational and environmental health hazards that have the potential to cause injury, illness, disease, adverse health conditions, or death and thus may be considered health and/or medical threats.
- Chemical hazards include contaminants in the air, water, soil, and food as well as exposures to industrial chemicals such as lead, solvents, pesticides, and chemical warfare agents.
- Physical hazards include climate conditions such as excessive heat and cold and physical environmental concerns such as operating at high altitudes and under conditions with high noise levels.
- Situational hazards may include physical threats (accidents, explosions), traumatic events (witnessing combat events), operational demands (high physical work demands, restricted sleep, limited food and water intake, prophylactic medications), and environmental living conditions.
Obviously, such situational threats as armed enemies present grave risks and often require the highest priority. Although certainly important in their ability to cause severe medical threats during deployment operations, infectious disease vectors, biological and nuclear warfare agents, and parasitic/entomological concerns are not described in this section.
Chemical Hazards
Over the years and with each conflict, environmental exposures to chemical hazards have occurred. A variety of different classes of chemical hazards present in a deployment or mission-specific environment have the potential to cause both acute and chronic health problems.
Chemical Warfare Agents
There is evidence that mustard gas (blistering agent) was present during World War I and the Iran–Iraq war in the mid-1980s. During the 1991 Persian Gulf deployment, potential exposure to low levels of sarin and cyclosarin either from the bombing of storage facilities or the destruction of stored munitions at Khamisiyah, Iraq, were described, although there were no documented reports of measured exposure or evidence of acute medical threats from these agents. Depending on the chemical warfare agent type, each has the capability to cause severe morbidity and mortality. Low-level exposures to these agents and related potential heath effects are not well characterized. Agents such as sarin and cyclosarin operate with similar toxic mechanisms to those of the organophosphate pesticide class, and therefore lower-level exposures have been hypothesized to result in central and peripheral nervous system symptoms in humans. Differences in specific brain tissue volumes and neurobehavioral functioning several years following the 1991 Persian Gulf deployment have been found to be associated with estimated exposure levels to sarin and cyclosarin (based on modeling efforts) (Heaton et al., 2007; Proctor et al., 2006).
Combustion Products
The potential for exposure to petroleum combustion products is widespread during deployment due to the many transportation vehicles, aircraft, and ships that operate on diesel, gasoline, and jet fuel. Also, during the 1991 Persian Gulf deployment, exposure to these combustion products occurred when oil wells were set on fire and burned for a number of months casting black smoke and particulate matter throughout the area of operation and when unvented tent heaters were used in enclosed areas.
Depleted Uranium
Both a heavy metal and source of radiation, depleted uranium is what remains after the more radioactive isotopes U234 and U235 are removed from uranium ore to make enriched uranium for nuclear reactor fuel. It is used as both armor on tanks and in certain munitions because of its ability to pierce or penetrate armor made with less dense metals. It was first used on a large scale during the 1991 Persian Gulf deployment. Depleted uranium may enter the body through inhalation, after combustion and aerosolization from explosive impact, or as a piece of shrapnel. Its primary target of toxicity is considered to be the kidney.
Solvents
During deployment missions, as within garrison occupational settings, and depending on military occupation, exposures to solvents such as jet fuel, degreasing agents, CARC paints, and decontamination solutions can be commonplace. Exposure to solvents has been found to result in increased health risks and symptoms, particularly to the central and peripheral nervous systems.