CHEMICAL DATA NOTEBOOK SERIES #74: ARSENIC TRIOXIDE
HAZARDOUS MATERIALS
Arsenic trioxide is a toxic, carcinogenic, sensitizing, nonflammable, tasteless, white, amorphous powder that may or may not be odorless. One reference claims it may have an odor that faintly resembles garlic. It is used in the manufacture of arsenic compounds, ceramic enamels, glass decolorizers, herbicides, insecticides, lead alloys, leather preservatives, paints, pigments, rodenticides, rust inhibitors, and wood preservatives.
PROPERTIES
Arsenic trioxide does not burn, but in a fire it may evolve highly toxic combustion products. It has a specific gravity of 3.87 and a molecular weight of 197.8. It melts at 599°F, at which temperature some forms of arsenic trioxide sublime. Other forms of arsenic trioxide melt at 835°F, a relatively low melting point for solid oxides. It is slightly soluble in water. Its molecular formula is As2O3
HAZARDS
Arsenic trioxide’s greatest hazard is toxicity. It is highly toxic by all methods of entry into the body. Ingesting arsenic trioxide severely damages the gastrointestinal tract. Initial symptoms may include delirium, disorientation, dizziness, headache, muscle spasms, collapse, shock, and eventually death.
It is also toxic when inhaled. The TLV-TWA (threshold limit value-time weighted average) for arsenic trioxide is 0.2 mg/m’ (milligrams per cubic meter of air). Inhaling arsenic trioxide produces symptoms that include anorexia; bloody stools; cold sweats; diarrhea; irritation of the throat, stomach, and upper digestive tract; and even death.
Arsenic trioxide may be absorbed through the skin. Symptoms include inflammation of the skin and some of the symptoms of ingestion and inhalation, including death. If arsenic trioxide enters the body through a wound, it produces many of the above symptoms, including death.
If arsenic trioxide contacts the eyes, it injures the cornea and causes excessive tearing and probable irreversible damage.
This extreme toxicity makes arsenic trioxide very useful as an insecticide, rodenticide, and herbicide. Of course, this same toxicity poses an extreme danger to human life. Firefighters never should come in contact with arsenic trioxide without wearing the proper respiratory, eye, and skin protection.
Deliberate poisoning of pets sometimes is done with arsenic trioxide, which usually is referred to simply as “arsenic.” This name, of course, is not correct. The correct chemical name of the subject of this article is arsenic trioxide. The name arsenic should be reserved for the element by that name. The practice of using arsenic as the name for arsenic trioxide, however, is so entrenched that it is likely to continue, which poses a problem for emergency responders when trying to identify which material is involved in an incident. There is a great deal of difference between the element arsenic and the chemical compound arsenic trioxide, even though both are toxic.
Arsenic trioxide also is known as a sensitizer. When it contacts the skin (and some of the material is absorbed), the area of contact may react to minor irritations and other chemical contact much more easily in the future. Arsenic trioxide has been found, through experimentation, to cause cancer.
Arsenic trioxide is considered a stable chemical: Under certain circumstances, usually including increased temperature and pressure, it does not decompose. In the heat generated by a fire, however, arsenic trioxide decomposes into very dangerous gases, including arsine, a highly toxic gas in its own right.
Stability is one property, but reactivity is quite another. Arsenic trioxide reacts violently and/or explosively with acids; aluminum; powerful oxidizers such as chlorine trifluoride, fluorine, oxygen difluoride, and sodium chlorate; and other chemicals such as rubidium carbide and zinc powder.
NONFIRE RELEASE
The release of even a very small amount of arsenic trioxide must he considered very serious. Emergency responders tend to treat small spills as nonhazardous situations. Arsenic trioxide’s TLV-TWA of 0.2 mg/m ‘ should impress on everyone that even a small amount of arsenic trioxide can be deadly.
A very small spill can be handled more quickly than a large release, but the salvaged product must be disposed of in a manner safe for human beings and the environment. Too many times, emergency responders flush small spills of many hazardous materials down a sewer, with the thought that the dangerous material will perform a good deed for society by poisoning rats (or other unsavory animals) in the sewer system. Doing this creates significant potential damage for human life and the environment; emergency responders must stop such irresponsible actions. Environmental experts will be included whenever safety forces are mobilized in a hazardous-materials incident. Consult these experts regarding the safe (and legal) disposal of even small amounts of hazardous materials. The toxic danger of arsenic trioxide cannot be overstated.
Arsenic trioxide usually is shipped as a white powder. A powder release, in some circumstances, is easier to control than a liquid release and most certainly is easier to contain than a gas release. Generally, any release of arsenic trioxide may be controlled by covering the product with any object or material that will keep the wind from blowing it around. A sheet of compatible material used as a cover probably also will keep rain from wetting the spilled material. Once the material has been contained, salvage should begin, to lessen the danger to human life and the environment. A professional salvage firm with properly educated, trained, and equipped personnel should perform salvage. This professional salvage team may be employed by the manufacturer of the arsenic trioxide. The manufacturer, shipper, or supplier of the product may employ other types of teams that can help in salvage and cleanup. Actively seek all qualified outside help. The proper environmental authorities should supervise salvage and cleanup work and the disposal of the contaminated product and soil.
Firefighters should become involved in salvage or cleanup of such a dangerous material as arsenic trioxide only if no professional help is available and if human life is endangered or the environment will be seriously damaged. Even in these circumstances, do not become involved in these operations unless you are fully protected against the possible contact of arsenic trioxide with your respiratory system, eyes, and skin.
If the arsenic trioxide cannot be adequately protected from the wind, evacuate downwind for at least a mile. If the wind is strong and its direction is constant, two miles might be safer. It might be a good idea to evacuate for a minimum of a half mile in all other directions, just in case the wind shifts. High-pressure water sprays and/or fog will disperse much of the wind-blown powder, wetting it and removing it from the air. If you use this technique, be sure to capture and contain all runoff water.
It is a good idea to build a containment dike around the spill, even if the product is a solid. Any water (from dispersal techniques and/or rain) will spread the deadly contamination. If there is any chance of rain occurring during the running of the incident, it is better to be prepared ahead of time.
Make every effort to keep the arsenic trioxide from entering a sewer or waterway. While it is true that rats and other inhabitants of the sewer system probably will be poisoned by the arsenic trioxide, this is an insignificant payoff when you consider the potential harm caused by the released arsenic trioxide. The sewage treatment facility might not be able to deal with arsenic trioxide in the system, or there might be no treatment facilities in existence. Even if the facility is warned in time to do something about the arsenic trioxide, it is not right or fair to “flush” your troubles downstream to the next users and let them handle the problem. By diking around all catch basins and sewer inlets, you can contain the material in one place for easier salvage and cleanup.
Since arsenic trioxide is only slightly soluble in water, any product that enters the sewer or a waterway probably will not dissolve very fast, except in a very large body of water or a very fast-moving stream or waterway. In still water, the powder sinks rapidly to the bottom (because of its specific gravity of 3 7) and sits there, dissolving very slowly. In moving water, it also sinks to the bottom as it moves downstream, tending to gather in low’ places on the stream or river bottom. It dissolves relatively faster in the moving water, but the speed at which it dissolves never will be fast. Immediately warn all downstream users of the water, including industry, of the contamination.
Should arsenic trioxide enter a stream or river, it is best to divert the water into a holding area until the arsenic trioxide can be removed. In slower-moving streams and rivers, a below-water dam will help keep the undissolved arsenic trioxide from moving downstream. Any undissolved product can be suctioned off the bottom. Once the arsenic trioxide reaches moving water, however, it is very difficult to keep it from spreading. If the water can be diverted and held, gently stir activated charcoal (carbon) into the water to adsorb the arsenic trioxide. The carbon recovered from the water will be highly contaminated with the adsorbed arsenic trioxide, and it must be disposed of in accordance with federal, state, and local regulations.
It might be possible for the water to be chemically treated to remove the contamination. The experts (the manufacturer of the arsenic trioxide and/ or any professional cleanup firm) should know how to do this.
Another mitigation technique involves dredging the stream, river, or other waterway to remove the conlamination. If it is the first time any chemical has entered this particular body of water, the environmental authorities might allow it. Hut if the body of water had been contaminated before, the environmental authorities will resist dredging because it is possible that the old contaminant could be “stirred up” and begin moving again. Never disturb a river, stream, or lake bed without the approval of the environmental authorities.
IDENTIFICATION NUMBERS AND RATINGS
CAS
(Chemical Abstract Services)
1327-53*3
STCC
(Standard Transportation Commodity Code)
4923115
RTECS
(Registry of Toxic Effects of Chemical Substances)
CG3325000
UN/NA
(United Nations/North America)
1561
CHRIS
(Chemical Hazard Response Information System) ATO
RCRA
(Resource Conservation and Recovery Act)
P012
DOT
(U.S. Department of Transportation)
Poison B
NFPA 704 Rating
3-0-0
IMO
(International Maritime Organization)
6.1, poisonous substance
FIRE SCENARIO
Arsenic trioxide does not burn or support combustion. It is an inorganic (or ionic) compound, and as a rule, inorganic materials do not burn. Arsenic trioxide contains three oxygen atoms bound together chemically as the trioxide ion. In a fire, this oxygen is not released in the form of gaseous oxygen that would be available to support combustion. This, however, does not imply that arsenic trioxide poses no dangers when involved in a fire. Therefore, since the incident commander determines firefighting procedures after proper initial and continual size-up, the structure or exposure fire may be fought with conventional procedures. The results of these firefighting procedures, how -ever, may produce an even more dangerous situation.
In some situations, the arsenic trioxide is packaged in paper bags and shipped 40 bags to a wooden pallet. If the wood used to construct the pallet is ignited by impinging flames, the wood plus the paper in the bags may be sufficient fuel to produce a high enough level of energy to break dow n the arsenic trioxide and cause the evolution of the highly dangerous arsine and other toxic gases.
If you use water to extinguish a fire in and among pallets of bagged arsenic trioxide, be aw are that the force of the stream can cause the arsenic trioxide to be spread around. Contain all runoff water used to fight a fire involving arsenic trioxide; it may be contaminated by the product. This includes the breakdown products of any foam used to fight the fire.
If pallets of arsenic trioxide are not burning and the water used to fight the surrounding or approaching fire reaches the paper bags, these bags will be weakened and may break open during overhaul and/or salvage and cleanup procedures. Much has been said in this series about firefighters not becoming involved in salvage and cleanup operations, but overhaul procedures, which must be done by firefighters, generally have been ignored. Firefighters looking for hot spots and other pockets of fire in rubble resulting from a fire in a warehouse or industrial structure where hazardous materials are manufactured, stored, or used are in extreme peril because of the possibility that the unburned hazardous material may have been released during the fire and extinguishment process. This is especially true with arsenic trioxide. Anyone performing overhaul functions after a fire where hazardous materials are present is extinguished must have on the proper respiratory, eye, and skin protection. This gets terribly complicated when multiple hazardous materials are involved, but all firefighters involved in any hazardous-materials incident must be properly protected at all times.
PROTECTIVE CLOTHING AND EQUIPMENT
Select protective clothing and equipment that provide the maximum respiratory, eye, and skin protection against arsenic trioxide. Regular turnout gear that is impervious to penetration by powdered materials may provide skin protection, which may include using methods to prevent entry of powders through sleeves and pants cuffs. Rubber boots, gloves, aprons, coveralls, and hoods may offer protection. Total encapsulating suits may not be required. If department standard operating procedures call for the use of total encapsulating suits, contact the manufacturer to determine how the suits protect against arsenic trioxide.
Chemical-resistant goggles that prevent powders from passing through are required under a face shield. Positive-pressure, self-contained breathing apparatus is required.
FIRST AID
Inhalation. Move the victim to fresh air; keep him/her calm and warm. If the victim’s breathing has stopped or becomes labored, administer artificial respiration, being aware that such action might expose the first-aid giver to the material in the victim’s lungs and/or vomit. Seek immediate medical attention.
Eye contact. Flush the eyes immediately for at least 15 minutes, lifting the eyelids occasionally. Seek immediate medical attention to prevent permanent damage.
Skin contact. Wash the affected areas of the body with large amounts of soap and w ater. If irritation continues after washing, seek medical attention concerning chemical absorption through the skin and sensitization.
Ingestion. If the victim is conscious, induce vomiting. Never try to make an unconscious person drink anything or vomit. Seek immediate medical attention *
SYNONYMS
arsenic
arsenic oxide
arsenic(III) oxide
arsenic sesquioxide
arsenicum album
arsenic white
arsenious acid
arsenious oxide
arsenious trioxide
arsenite
arsenolite
arsenous acid
arsenous acid anhydride
arsenous anhydride
arsenous oxide
arsenous oxide anhydride
arsentrioxide
arsodent
claudelite
claudetite
crude arsenic
diarsenic trioxide
white arsenic
