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Because of recent terrorist events many workers have expressed concern about the possibility of a terrorist attack involving nerve agents. In 1995, twelve people were killed when the nerve agent sarin was released in the Tokyo subway system. The following frequently asked questions will help workers understand what nerve agents are and how they may affect their health and safety.
What are nerve agents?
Nerve agents are highly toxic chemicals called "organophosphates" that poison the nervous system and disrupt bodily functions which are vital to an individual’s survival. They were originally produced in a search for insecticides, but because of their toxicity, they were evaluated for military use.
What are the different forms of nerve agents and their properties?
Nerve agents, depending on their purity, are clear and colorless or slightly colored liquids and may have no odor or a faint, sweetish smell. They evaporate at various rates and are denser than air, so they accumulate in low areas. Nerve agents include tabun(GA), sarin(GB), soman(GD), and VX.
Why are we concerned about nerve agents as a terrorist’s weapon?
There are large stockpiles of nerve agents which, if obtained by terrorists, could be released using bombs, explosives, spray tanks, or rockets.
How long will aerosolized nerve agents persist in the environment?
The "G" agents tend to be volatile liquids which do not persist in the environment very long. The "VX" tends to be highly persistent and thus non-volatile. When compared to the "G" agents, "VX" is much more lethal and persistent. See the following table for more information:
Types and Characteristics Chemical Agents
*ARMY FIELD MANUAL NO. 8-10-7. Health Service Support in a Nuclear, Biological, and Chemical Environment.Health Effects
How do nerve agents affect people?
Nerve agents are highly toxic and rapidly affect exposed individuals. Nerve agents enter the body primarily through the respiratory tract, although they may be absorbed through the eyes or skin. In the liquid state, nerve agents are hazardous via skin or eye contact and through ingestion. Generally, all nerve agents are highly toxic and fast acting.
When a person is exposed to a nerve agent, the nerve agent, upon entering the body, inhibits the normal actions of acetylcholinesterase; a chemical within the body whose normal function it is to break down the chemical acetylcholine. Acetylcholine causes muscular contraction. What nerve agents do to acetylcholinesterase is inhibit it from breaking down acetylcholine which in turn causes violent muscle spasms.
What are the symptoms of nerve agent poisoning?
When an individual is exposed to low amounts of a nerve agent (as a gas or aerosol) the initial symptoms are a runny nose, contraction of the pupils, deterioration of visual accommodation, headache, slurred speech, nausea, hallucinations, pronounced chest pains, and an increase in the production of saliva. At higher doses, these symptoms are more pronounced. Coughing and breathing problems also begin to occur. The individual then may begin to go into convulsions possibly progressing to coma or death. At even higher doses, an exposed individual would almost immediately go into convulsions and die from suffocation because of the simultaneous shut-down of the nervous and respiratory systems.
See the following links for more information on health effects:
How do I protect myself from nerve agents?
If you are exposed to a nerve agent attack, move away from the impacted area quickly without passing through the contaminated area. It may be necessary to "shelter-in-place" if you can’t get out of a building or if the nearest place with clean air is indoors.
If available, a good way to protect yourself from nerve agents is to wear appropriate chemical protective clothing and respiratory protection. However, protective equipment does not always work against nerve agents. The effectiveness is determined by the materials of construction, the type and level of exposure, and duration of exposure.
What does it mean to "shelter in place?"
"Shelter in place" means to go indoors, close up the building, and wait for the danger to pass. If you are advised to shelter in place, close all doors and windows; turn off fans, air conditioners, and forced-air heating units that bring in fresh air from the outside; only recirculate air that is already in the building; move to an inner room or basement; and keep your radio turned to the emergency response network or local news to find out what else you need to do.
What should I do if I have been exposed to a nerve agent?
If you have been exposed to a nerve agent, remove all clothing immediately and wash with copious amounts of soap and water. Seek emergency medical attention.
Is there any treatment for persons exposed to nerve agents?
Because nerve act rapidly, treatment must begin immediately after exposure or death may occur. A general antidote to nerve agents is a combination of atropine and a reactivator. Atropine protects against the excess of acetylcoline formed during nerve agent poisoning. The reactivator's job is to restore acetylcholinesterase to its normal functions. The degree of difficulty in combating the nerve agent depends greatly on the quantity and type of nerve agent.
Health care professionals use an auto-injector to inject a mixture of atropine and the reactivator into patients exposed to nerve agents. The auto-injector consists of the two active components which are injected into an exposed individual through the use of a very long needle. The auto-injector is usually injected into an individual's thigh or another area where the antidote can reach the heart relatively quickly.
Is there a medical test to show whether I've been exposed to nerve agents GA, GB, GD, or VX?
Yes, medical tests can determine whether you have been exposed to nerve agents. There are tests to measure degradation products of nerve agents in the urine, but these are not generally useful. A different kind of test measures the levels of a substance called cholinesterase in the blood. If these levels are less than half what they should be, and you were exposed to nerve gases, you may experience symptoms of poisoning. Cholinesterase levels in the blood can remain low for months after you have been exposed to nerve agents. Measurement of cholinesterase levels in blood is not specific for exposure to nerve agents.
Has the federal government made recommendations to protect worker health?
OSHA has not set occupational exposure levels for exposure to nerve agents. However, other government departments and agencies have published existing and proposed standards.
How should first responders prepare for a release of nerve agents?
First responders should consider the possible impact of a release and potential exposure to nerve agents and address this in their health and safety plan (HASP). The safety and health plan should include guidelines such as: monitoring, detection, awareness training, personal protective equipment, decontamination, and medical surveillance of acutely exposed workers.
What equipment can first responders use to detect if a nerve agent is present?
The military has a number of devices to detect nerve agent vapor and liquid. The most portable of the vapor detectors are the M256A1 card or ticket and the Chemical Agent Monitor (CAM). The most simple liquid detectors are the M8 and M9 papers. Direct reading instruments that are available include specialized gas chromatographs (minicams) and ion mobility spectrometers such as the APD 2000. Since some of these detectors cannot adequately detect the agents at safe airborne levels, users should be trained in regards to the use and limitations of the detectors. Listed below is a table of military detection and monitoring equipment: Military Detection and Monitoring Equipment
Reference from National Research Council’s Chemical and Biological Terrorism: Research and Development to Improve Civilian Medical Response.
What personal protective equipment (PPE) should first responders use?
When an active release is occurring, or the release has stopped but there is no information about the duration of the release or the airborne concentration of nerve agents, don level A protection. The requirement of OSHA’s Hazardous Waste Operations and Emergency Response (HAZWOPER) standard (29 CFR 1910.120(q)) provides additional information for responding to hazardous substance releases including nerve agents.
For additional information see CBRN Personal Protective Equipment Selection Matrix for Emergency Responders - Nerve Agents.
How should healthcare workers prepare to respond to a nerve agent release?
Healthcare facilities should have a health and safety plan in place that addresses the possibility of receiving patients exposed to nerve agents from a terrorism event. The document "OSHA Best Practices for Hospital-Based First Receivers of Victims" contains practical information developing a emergency management plan and includes victim decontamination, personal protective equipment, and employee training.
How do I decontaminate a patient?
Healthcare professionals should don appropriate gloves and respiratory protection and then remove contaminated clothing from victim and thoroughly wash exposed areas with soap and water. Healthcare professionals should also wash hands after removing any protective gloves and any other potentially exposed body surfaces.
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