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                                METHYL BROMIDE
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                                By: Frank L. Fire
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         Methyl Bromide is a toxic, corrosive, irritating, colorless gas
     with a sweet odor and burning taste. It is usually shipped and stored
     as a liquid under pressure. It is used as a degreaser, disinfectant,
     fumigant, herbicide, pesticide, refrigerant, solvent, and as a raw
     material for making other chemicals.
         Although methyl bromide is considered practically nonflammable, it
     will burn. As a gas, it has no flash point, but it has a flammable
     range of 10% to 16%. Some references show the flammable range from
     13.5% to 14.5%, which would make ignition difficult since it would
     have such a narrow flammable range (of 1%). However, within whatever
     its flammable range is, it will ignite at 999`F.
         A word of caution is due here. There are several methods of
     determining flammability properties of materials. the fact that
     different values show up in different references for the same product
     indicates that only that different methods may have been used to
     determine those values. An emergency responder needs to know what
     hazard he or she faces when responding to an incident, and the
     information contained in one reference book may not provide all the
     information needed.  When emergency responders find different
     information in different references, they must choose the most
     conservative of the numbers in order to protect themselves.  This
     writer, when researching information for this series of articles,
     always uses the information that will indicate the lowest ignition
     temperature, the widest flammable range, the lowest boiling point, et
     cetera from all the references sources examined. This is done to
     provide the reader with the most conservative set of properties
     possible, so that the user of such information will have the best
     chance of handling the incident without injury or death to himself or
     herself.
         The flammable range of methyl bromide might indeed be 13.5% to
     14.5%, but would you bet your life or the life of those in your
     command on it? As long as there is evidence that the range might be
     wider, it is absolutely necessary for the number one exposure, the
     emergency responder, to investigate the differences, and, taking the
     conservative approach, accept the wider flammability range (or more
     conservative property of another nature) until it is disproven.
         In its liquid form, methyl bromide has as specific gravity of 1.68;
     as a gas, it has a vapor density of 3.27. Its molecular weight is
     94.94; it has a boiling point of 135~F, and is very slightly soluble
     in water.
         Methyl bromide is toxic by all routes of entry into the body. Since
     it is a gas shipped and stored as a liquid, any release of the gas from
     the container will be under pressure, and any liquid released will
     generate large amounts of gas. It has a TLV-TWA (threshold limit value -
     time weighted average) of 5 ppm and STEL (short term exposure limit) of
     15 ppm.
         Inhalation of methyl bromide in low concentrations may cause
     blurred vision, slurred speech, headaches, nausea, and vomiting.
     Continued exposure will produce tremors and then convulsions. High
     concentrations may produce irritation of the lungs which may cause
     pulmonary edema. Permanent damage may be done to the central nervous
     system and the kidneys. Prolonged exposure may cause unconsciousness
     and death. One of the major problems with methyl bromide is that some
     of the symptoms may not manifest themselves for from short periods of
     time to days.
         Contact with the skin may cause blistering burns, but the vapors
     may be absorbed through the skin, causing many of the previously listed
     symptoms. Less severe contact can produce skin rashes.
         Contact with the eyes may produce severe irritation. Eye injury may
     be reversible, even though temporary blindness may occur.
         Ingestion of methyl bromide will cause damage to the mouth and
     esophagus because of its corrosiveness, and death will probably be
     caused by its toxic nature.
         Methyl bromide is corrosive, especially toward aluminum, magnesium,
     and any alloys containing these metals. It is particularly dangerous
     when in contact with aluminum since it will form an organic-metallic
     compound that is air-reactive and will begin burning spontaneously.
         It will also react with strong oxidizing and reducing agents,
     mineral acids, caustics, alkali on alkaline earth metals, nitrides,
     dimethyl sulfoxide, other metals, and organic chemicals such as amines,
     azo and diazo compounds, and hydrazines. It does not react with water.

         NONFIRE RELEASE

         Since methyl bromide is toxic, all efforts must be directed at
     preventing any contact with human life. Not only does this mean control
     of the vapors, but the liquified product must be prevented from getting
     into systems that would effect humans by its toxicity or corrosiveness.
     This means that steps must be taken to prevent its entry into sewers
     and waterways, among other systems.
         Methyl bromide, in its liquified state, may be contained by
     construction of containment ponds with the use of diking around the
     spill with soil, sand, clay, or other materials. A containment pit may
     be dug near the spill, and the product's flow may be directed into the
     pit by digging trenches that lead from the spill to the pit. In either
     case, the liquid may percolate into the soil, spreading the
     contamination.  Contamination will also spread by contact of the
     product with the sides of the containment pit or the diking material
     used in constructing the pond.
         In all cases, the actions of the emergency responders in containing
     the release should be guided by the proper environmental authorities,
     once it is determined that there is no immediate danger to human life.
     The environmental authorities will have a better idea of the release's
     potential damage to the environment, and fire departments and other
     emergency responders should realize this.
         In other words, the role of the first responders at a haz-mat
     incident should be life rescue; prevention of injury to exposed
     persons; and prevention of the spread of harm to humans from the
     original incident scene (containment or stabilization).  Once that is
     accomplished, (or simultaneously, if possible), potential damage to
     the environment must be avoided; decisions regarding this aspect of
     emergency response are best made by environmental protection
     specialists.  Prevention of property damage is probably now the
     lowest ranking (but still important) consideration the emergency
     responder must take.
         Once the methyl bromide is contained, remember that this material
     is actually a gas in liquified form, and when it is released from its
     container, the product's temperature may be above its boiling point
     (38.3~ F). This will produce the rapid evolution of methyl bromide gas,
     which will drift with the wind, hanging close to the ground because of
     its relatively high vapor density of 32.7.  These vapors will travel
     great distances (unless disturbed by the wind), and accumulate in low
     places or confined areas. Any unprotected entry into these areas of
     high concentration of the gas could produce severe injury or death.
     Evacuation of inhabitants of the area, especially downwind, must
     always be considered as a tactic.
         The colorless vapors of methyl bromide can be dispersed by using
     high-pressure water spray or fog patterns, as long as efforts are
     made to reduce the chance of spread of contamination by containing the
     runoff.  Foam may be applied to try to slow the evolution of vapors,
     as long as the foam blanket is replenished as it breaks down. remember
     that any liquid products of the foam will add to the volume of the
     liquid being contained.  This must be planned for if foam application
     is the tactical choice.
         The liquified methyl bromide should be removed from the containment
     area and placed into secure containers as soon as possible. This may
     be done by vacuuming the liquid from the pond or pit with compatible
     pumping equipment. Whatever contaminated soil remains after the liquid
     is suctioned up will have to be removed and disposed of under the
     supervision of the proper environmental authorities and in accordance
     with federal, state, and local laws. All salvage and clean up
     operations should be done by properly educated, properly trained and
     properly equipped professionals.
         During salvage and clean up operations, care must be taken to
     eliminate all ignition sources, and attention must be given to prevent
     an ignition source from appearing during any exposure to the gas. Even
     though methyl bromide is considered practically non-flammable by some
     references, and, as explained earlier, its flammable range may be 10%
     to 16% (or 13.5% to 14.5%), the fact is that methyl bromide gas will
     ignite explosively at some concentration between 10% and 16% as long
     as there is energy sufficient to raise some small portion of the gas
     to 999` F.  All common sources will provide that energy.
         Should the liquid reach a sewer, all downstream receivers of the
     sewer system must be notified immediately. If the liquid reaches a
     waterway, all downstream users of the water must be warned that
     contaminated water may be moving their way. The proper environmental
     authorities have the equipment, training, education, and experience
     necessary to take sewage and/or water samples to determine the degree
     the contamination spread and of the potential danger (or lack thereof)
     downstream.
         The liquid will sink slowly to the bed of the waterway because of
     its specific gravity of 1.68. It will not "sink like a rock" but will
     eventually make it to the bed of the waterway, unless the current is
     strong.  Once on the bottom, it may continue to move downstream, and
     collect in deep spots. If this occurs, the stream may be diked and the
     methyl bromide suctioned from beneath the surface of the water.
         If the waterway is small enough, the water may be diverted to a
     field or other low-lying area adjacent to the stream, and the spilled
     product may be collected either by suctioning or by the use of an
     absorbent material such as activated charcoal. Once the contaminated
     water is collected, the activated charcoal (carbon) may be mixed with
     the water. The methyl bromide liquid will adhere to the surface of the
     carbon, which may then be dredged from the bed of the contaminated
     water.  Keep in mind that methyl bromide is really a gas, and the
     liquified methyl bromide, as it boils at temperatures above 38.3~ F,
     will be evolving toxic gas. The activated charcoal, with the methyl
     bromide adhered to the surface, should be placed immediately into a
     secured container, since it will be nearly as hazardous the liquid
     itself.  During all operations involving released liquified methyl
     bromide, the toxic gas will be evolved.
         Should the original release of methyl bromide from its container
     be in the gaseous form rather than the liquid, a dispersal of the gas
     by a high-pressure spray or fog can be used. If this is not possible
     and the gas continues to leak (threatening lives because of its toxic
     nature), a deliberate ignition of the gas may be more desirable than
     the uncontrolled movement of toxic vapors. This should be done only
     if it can be determined that there will not be an explosion of the gas
     upon ignition.  Deliberate burns are very radical mitigation
     techniques, and should be carried out only on the advice of the proper
     resource people, and executed only under conditions that will reduce
     the hazard rather than adding to it or producing one more severe.

         FIRE SITUATIONS

         Liquified methyl bromide will almost always be stored or shipped
     at temperatures above its boiling point, so the gas is always ready
     to escape from its container. Even at temperatures below 38.3~F,
     methyl bromide exhibits a vapor pressure (as do all liquids below
     their boiling points), which means the liquid will almost always
     produce deadly or flammable amounts of the gas.  Any time heat from
     impinging flames or radiated heat from a fire or other heat source
     contacts the methyl bromide container, the liquid will heat up and
     produce more vapor, until a state of equilibrium exists between the
     liquid phase and the gas phase within the container. As more heat is
     absorbed by the container (and consequently, the contents), more and
     more gas is evolved, causing the pressure within the container to
     rise.  This will continue until equilibrium is again reached, or the
     design pressure of the pressure relief valve (if there is one present)
     is surpassed, at which time methyl bromide gas will be vented to the
     atmosphere.  If the pressure rises faster than the vent can act to
     relieve it, or the valve malfunctions (or is not present),
     catastrophic failure of the container will occur when the design
     strength of the container is surpassed.  If this occurs, the escaping
     gas may ignite, and a resulting explosion, a BLEVE, is possible with
     methyl bromide.
         All containers being heated by a fire or other heat source should
     be cooled from a distance that would provide safety to all personnel
     in the event of such an explosion. Water should be delivered from as
     far from the container as possible with the use of unmanned appliances.
     The radius of evacuation distance depends upon the size of the
     container.  A rail tank car, for example, should cause an evacuation
     of at least 2,500 feet.
         If the threatened container is "out in the middle of nowhere",
     (that is, there are no threatened exposures, including human life), no
     attempt to approach it is necessary. In other words, when there is no
     life threatened by the explosion of the container, there is no need
     for emergency responders to put their lives in danger. If the
     environment is threatened (again, the determination must be made by
     the proper environmental authorities), action can be taken based on
     the severity of the threat. In recognizing that there may be an
     explosion, escaping gas may be allowed to ignite. The technique of
     deliberate ignition may be attempted sooner in the scenario, as long
     as it presents no danger to human life.

         PROTECTIVE CLOTHING AND EQUIPMENT

         Protective equipment and clothing for use in an incident involving
     methyl bromide should be selected to prevent the contact of liquid
     and/or gas with the eyes, skin, or respiratory system. This may
     include rubber boots, gloves, aprons, the proper face shields,
     splash-proof chemical safety goggles, and positive-pressure, self-
     contained breathing apparatus.  Total encapsulating suits should be
     worn anytime contact with the liquid or gas is possible.  Protection
     from methyl bromide is claimed by some manufacturers of suits made
     from butyl rubber, neoprene, and Viton.  Other manufacturers do not
     recommend butyl or neoprene.  It is of paramount importance that the
     user of the chemical protective suits consult the manufacturer's
     recommendations for their particular material.


         FIRST AID

         In the event of inhalation, the victim must be moved immediately
     to fresh air and kept quiet and warm. If breathing stops or becomes
     labored, artificial respiration should be administered in a manner to
     protect the first-aid provider from the product in the victim's lungs.
     Medical attention must be immediate.
         For skin contact, all contaminated clothing must be removed and
     the affected area must be washed with large amounts of water.
     Immediate medical attention is necessary.
         For eye contact, the eyes must be flushed immediately for fifteen
     minutes, occasionally raising the eyelids. Again, medical attention
     is required immediately.
         If the victim has ingested methyl bromide, he or she must be made
     to drink a strong solution of salt water. Do not attempt to make an
     unconscious person drink anything. The victim must not be made to
     vomit, unless immediate medical attention is not available.



     The above was taken from:

     Fire Engineering   March 1989
     Chemical Data Notebook Series # 34