Miscellaneous Hazards

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Materials in Class 9 present hazards during transportation but do not meet the definition of any other hazard class. They may be anesthetics, noxious or elevated temperature materials, hazardous substances, hazardous wastes or marine pollutants.

These materials may be encountered as solids of varying configurations, gases and liquids. Examples are asbestos, dry ice, molten sulfur and lithium batteries. These materials would carry the Class 9 miscellaneous hazardous materials placard, which is white with seven vertical black strips on the top half.

Also included in Class 9 are Other Regulated Materials (ORM-D), Con-sumer Commodities. They are "materials that present a limited hazard during transportation due to the form, quantity and packaging." Some of these materials, if shipped in tank truck quantities, would fit into another class but because the individual packaging quantities are so small, the hazard is considered limited by the U.S. Department of Transportation (DOT) and they are labeled ORM-D.

Generally, ORM-D materials are destined for use in the home, industry and institutions. They are in small containers, including aerosol cans, in quantities of a gallon or less. In fires, many small containers can became projectiles as pressure builds up inside from the heat and the containers explode. Aerosol cans can be particularly dangerous because they are already pressurized, and exposure to heat can cause them to explode and rocket from the pressure.

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Photo by Robert Burke
Markings indicate that this insulated rail car is carrying a cargo of Class 9 molten sulfur.

Those materials found in industry and institutions are usually service products used in cleaning and maintenance rather than in industrial chemical processes. Examples of ORM-D materials include low-concentration acids, charcoal lighters, spray paints, disinfectants and cartridges for small firearms. Even though the containers may be small, the products inside can contaminate responders and kill and injure if not handled properly.

No one specific hazard can be attributed to Class 9 materials. The physical and chemical characteristics mentioned in the first eight hazard class articles may be encountered with Class 9 materials. The difference is that the quantities may be smaller or the materials classified as hazardous wastes, which can include almost any of the other hazard classes. With miscellaneous hazardous materials it is important to obtain more information about the shipment to determine the chemical names and the exact hazards of the materials involved.

Some Class 9 placards on vehicles include four-digit UN identification numbers. The corresponding information in the DOT's Emergency Response Guide (ERG) may not give detailed names of the materials. In such cases, shipping papers or other sources must be consulted to determine the exact hazard of the shipment.

In addition to the Class 9 placard, a second placard may appear next to it with the word HOT. The word may also appear outside of a placard by itself. What it indicates is that the material inside has an elevated temperature that may be a hazard.

An elevated temperature material is usually a solid that has been heated until it melts and becomes a molten liquid. The change is in physical state only; the material's chemical characteristics are the same. There may, however, be vapors produced from molten materials that are not be present in the solid form. These vapors may be flammable or toxic.

Water in contact with molten materials can cause a violent reaction and instantly turn to steam. If this happens inside a container, the pressure buildup from the steam can cause a boiler-type explosion. The steam, which is a gas, builds up pressure inside what is usually a non-pressure container. When the container can no longer withstand the pressure, it fails. The molten material inside may be splattered around by the explosion.

Two molten materials are specifically listed in the hazardous materials tables in 49 CPR: molten aluminum and molten sulfur.

Molten aluminum has a UN identification number of 9260. When referenced in the ERG, it refers to Guide 77 for hazards of the material. (Guide 77 was an addition to the 1993 version of the ERG. Molten aluminum is the only material that refers to this guide.) The guide indicates the material is above 1,300 degrees Fahrenheit and will react violently with water, which may cause an explosion, and release a flammable gas.

The molten material in contact with combustible materials may cause ignition if the molten material is above the ignition temperature of the combustible. For example, gasoline has an average ignition temperature of around 800 degrees F. Diesel fuel has an average ignition temperature of around 400 degrees F. In an accident, gasoline or diesel fuel could be spilled. The molten material could be an ignition source for the gasoline or diesel fuel. When contacting concrete on a roadway or at a fixed facility, molten materials could cause spalling and small pops. This could cause pieces of concrete to become projectiles. Contact with the skin would cause severe thermal burns. No personnel protective clothing will adequately protect responders from contact with molten materials.

There are other molten materials that are not as hot as molten aluminum. Molten sulfur refers you to Guide 32 in the ERG. Molten sulfur, carrying the number 2448, may ignite combustible materials with which it comes in contact. It has a melting point of about 245 degrees F. Molten sulfur in transportation would be above that temperature, but not as hot as molten aluminum. Contact would still cause severe thermal burns, and the vapor is toxic.

Hot asphalt in liquid form can also cause combustion of combustible materials and severe thermal burns. Asphalt that has been heated to become a hot liquid refers you to Guide 27 in the ERG for hazard information. When referencing Guide 27, the information will indicate that the materials may be HOT. Asphalt has a boiling point of >700 degrees F and a flash point of >400 degrees F. The ignition temperature is 905 degrees F.

Fires involving asphalt should be fought with care. Water may cause frothing, as it does with all combustible liquids with flash points above 212 degrees F. This does not mean that water should not be used; just be aware that the frothing may be violent and the water contacting the molten material may cause a reaction. Asphalt has a UN number of 1999 for all forms.

Asbestos white, gray, green, brown and blue is an impure magnesium silicate mineral which occurs in fibrous form. It is non-combustible and was used extensively as a fire retardant material until it was found to cause cancer. Asbestos is highly toxic by inhalation of dust particles. The UN number for white asbestos is 2590. The primary uses of asbestos are in fireproof fabrics, brake linings, gaskets, as a reinforcing agent in rubber and plastics and as a cement reinforcement. Many uses of asbestos are being banned because of the cancer danger of the material.

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Photo by Robert Burke
A box truck with an overpack drum underneath usually means hazardous waste is in the cargo area. The identification number 3077 refers to solid hazardous waste.

Ammonium nitrate fertilizers that are not classified as oxidizers are considered miscellaneous hazardous materials. This type of fertilizer contains other materials, including controlled amounts of combustible materials. Mixtures of ammonium nitrate, nitrogen and potash that are not more than 70 percent ammonium nitrate and don't have more than 0.4 percent combustible material are included as miscellaneous hazardous materials. Additionally, ammonium nitrate mixtures with nitrogen and potash, with not more than 45 percent ammonium nitrate, may have combustible material which is unrestricted in quantity. The UN number for these mixtures is 2071.

Solid carbon dioxide (dry ice) presents a danger in transportation because of the carbon dioxide gas produced as it warms. This warming is much like water ice melting, although no liquid is formed in the case of dry ice. Dry ice sublimes, going directly from a solid to a vapor or gas without becoming a liquid. While carbon dioxide gas is non-toxic, it is an asphixiant and can displace oxygen in the air or in a confined space. Carbon dioxide gas is used as a fire extinguishing agent. The UN number for solid carbon dioxide is 1845.

Solutions of formaldehyde, 30 to 50 percent (such as those used in preservatives), are listed as miscellaneous hazardous materials. These solutions are non-flammable and the toxicity is below the requirements for a poison liquid. However, the material may still be carcinogenic. Formaldehyde solutions usually contain up to 15 percent methanol to retard polymerization. The UN number for non-flammable solutions is 2209.

Polychlorinated biphenyls (PCBs) are composed of two attached benzene rings, with at least two chlorine atoms in the compound. PCBs had been widely used in industry since 1930 because of their stability; however, it was this same stability that led to their downfall. They are highly toxic, colorless liquids with a specific gravity of 1.4 to 1.5, which is heavier than water. They are not biodegraded, and remain as an ecological hazard through water pollution.

The manufacture of PCBs was discontinued in the United States in 1976. The material that remains is considered hazardous waste, and is shipped as a miscellaneous hazardous material. According to Environmental Protection Agency (EPA) statistics, from 1988 to 1992, PCBs accounted for 3,586 accidental releases, resulting in 34 deaths. This was the number-one chemical involved in accidental releases during that period.

Batteries containing lithium are listed as miscellaneous hazardous materials. The storage batteries are composed of lithium, sulfur, selenium, tellurium and chlorine. The UN numbers assigned to them depend on the use and composition of the batteries. Lithium batteries contained in equipment has the number 3091. Batteries with liquid or solid cathodes, not in any kind of equipment, are given the number 3090.

Also listed in CPR 49 hazmat tables are solid materials, fish meal or fish scrap that has been stabilized. Fish meal is subject to spontaneous heating. These materials are given the UN number 216. Castor beans, castor meal or flakes may also undergo spontaneous heating. The UN number is 2969. Other materials include cotton (wet, 1365), polystyrene beads (2211), self-inflating lifesaving appliances (2990; not self inflating 3072), environmentally hazardous liquids or substances (3077), hazardous waste/liquid (3082) and hazardous waste/solid (3077). Hazards also are presented by self-propelled vehicles with internal combustion engines or electric storage batteries, and electric wheelchairs with spillable or non-spillable batteries.

Titanium dioxide, TiO2, is a white powder and has the greatest hiding power of all white pigments. It is non-combustible; however, it is a powder, and when suspended in air may cause a dust explosion, if an ignition source is present. It is not listed in the DOT hazardous materials table and is not considered hazardous in transportation by the DOT. The primary uses are as white pigment in paints, paper, rubber and plastics, in cosmetics, welding rods, and in radioactive decontamination of the skin.

Sodium silicate, 2Na2OSiO2, also known as water glass, is the simplest form of glass. It is found as lumps of greenish glass soluble in steam under pressure, white powders of varying degrees of solubility, or cloudy or clear liquids. It is non-combustible; however, when the powdered form is suspended in air, it could cause a dust explosion if an ignition source is present. The glass form could also create a hazard to responders in an accident. It is not listed as a hazardous material in the DOT hazardous materials table. The primary uses are as catalysts, soaps and adhesives and for water treatment, bleaching, waterproofing and as a flame retardant.

Bisphenol A, (CH3)2C(C6H4OH)2, is made up of white flakes that have a mild phenolic odor. It is insoluble in water. Bisphenol A is combustible with a flash point of 175 degrees F. It is not listed in the DOT hazardous materials tables. It is used in the manufacture of epoxy, polycarbonate, polysulfone and polyester resins, as a flame retardant and as a fungicide.

Urea (carbamide), CO(NH2)2, is composed of white crystals or powder and is almost odorless, with a saline taste. It is soluble in water, and decomposes before reaching its boiling point. Urea is non-combustible. The primary uses of urea are in fertilizers, animal feed, plastics, a stabilizer in explosives, flame proofing agents, pharmaceuticals and cosmetics. Urea appears to be both a ketone and anamine by structure and molecular formula; however, it is neither, nor does it have any of the characteristics of either family.

Hot materials such as asphalt can cause serious thermal burns if contacted with parts of the body. The TV program "Rescue 911" highlighted a rescue operation that involved hot asphalt. In that incident, a dump truck being used to haul solid hot asphalt to patch roadway holes collided with a car. As a result of the collision, the load of hot asphalt was dumped into the car, covering the driver to the point that he could not escape. Before rescuers could remove the driver, he suffered severe second- and third-degree thermal burns from the hot asphalt.

This same hazard exists with all elevated temperature materials. Responders should work carefully around transportation vehicles that have the HOT placard or the word HOT on the container.

Emergency responders should have a thorough understanding of the physical and chemical characteristics of hazardous materials, including parameters of combustion, water and air reactivity, incompatibilities with other materials, and the effects of temperature and pressure.

Responders should have the same level of understanding of hazardous materials as they do of firefighting, EMS protocols and law enforcement procedures. All emergency response incidents have the potential to involve hazardous materials.


Robert Burke, a Firehouse® contributing editor, is a Maryland-based certified Hazardous Materials Specialist and has served on state and county hazardous materials response teams. He has 16 years' experience in career and volunteer fire departments, attaining the rank of assistant chief, and has served as a deputy state fire marshal. He holds an associate's degree in fire protection technology and a bachelor's degree in fire science. Burke is an adjunct instructor at the National Fire Academy and the Delaware County, PA, Fire Academy.

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