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Hazard Class Definitions

Carcinogen

Any substance or agent capable of causing or producing cancer in mammals, including humans. A chemical is considered to be a carcinogen if it has been listed as such by the International Agency for Research on Cancer (IARC), by the National Toxicology Program (NTP) (latest edition), or if it is regulated by OSHA as a carcinogen.

Combustible Liquid

A liquid having a flash point above 140ºF (60ºC), but below 200ºF (93.3ºC).

Compressed Gas

Any material or mixture that, when enclosed in a container, has an absolute pressure exceeding 40 psi at 21.1°C, or has an absolute pressure greater than 104 psi at 54.4°C, or any flammable material having a vapor pressure greater than 40 psi at 37.8°C. Compressed gases include liquefied petroleum gas.

Corrosive

Acid, base, or mixture having a pH less than or equal to 2 or greater than or equal to 12.5, and materials that burn the skin and cause irreversible tissue damage. Examples are strong mineral acids (chromic, sulfuric, hydrochloric, or nitric), strong alkalis (potassium hydroxide, sodium hydroxide), rust removers, and acidic or alkaline cleaning fluids.

Cryogenic

Liquefied gases used to provide extremely low temperatures (< –90ºC) for frozen storage and experimentation. Hazards associated with their use include cold burns, frostbite, high pressure gases, explosions, implosions, toxicity and asphyxiation.

Explosive

Any substance, article, or device which is designed to function by explosion, which is a rapid chemical reaction with the production of noise, heat, and violent expansion of gases.

Flammable Gas

Any material which is a gas at 20 ºC or less and 14.7 psi of pressure which is ignitable at 14.7 psi, when in mixture of 13% or less by volume with air or has a flammable range of at least 12%, regardless of the lower limit. Butane and acetylene are examples of flammable gases.

Flammable Liquid

Liquid with a flashpoint of not more than 140°F (60°C).

Flammable Solid

May cause a fire through friction, absorption of moisture, spontaneous chemical change, ignited readily, and burns so vigorously as to create a serious hazard. Naphthalene, matches, aluminum powder, and magnesium are examples of flammable solids.

Highly Toxic

A substance having an Oral LD50 (Lethal Dose, 50%) in rats of <50 mg/kg; Skin contact LD50 in rabbits of <200 mg/kg; Inhalation LC50 (Lethal Concentration, 50%) in rats of <200 ppm for 1 hour; Inhalation LC50 in rats of <2,000 mg/m3 for 1 hour.

Irritant

A chemical/material that causes a reversible inflammatory effect on living tissue, and may cause soreness, redness or discomfort.

Mutagen

A substance or agent capable of altering the genetic material (chromosomes or genes) in a living cell.

Organic Peroxide

Any organic compound containing the bivalent oxygen-oxygen structure (O=O), and which may be considered a structural derivative of hydrogen peroxide, where one or more of the hydrogen atoms have been replaced by organic radicals.

Oxidizing Gas

A gas which may, generally by providing oxygen, cause or contribute to the accelerated combustion of other materials.

Oxidizer

Any compound that spontaneously evolves oxygen at room temperature, causes an oxidation reaction, initiates or promotes combustion, thereby causing fire. The term may include such chemicals as peroxides, chlorates, perchlorates, nitrates, and permanganates.

Pyrophoric

Any liquid or solid that will ignite spontaneously in air at about or below 140ºF (54.4 ºC).

Sensitizer

A chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure to the chemical.

Teratogen

A substance or agent, exposure to which will result in the development of malformations in the fetus of a pregnant female.

Toxic

A substance having an oral LD50 in rats of 50-500 mg/kg; Skin contact LD50 of 200 mg/kg – 1 g/kg; Inhalation LC50 rats 200 ppm – 2 ppb for 1 hour; Inhalation LC50 rats of 2,000 g/m3 – 20 g/m3 for 1 hour.

Unstable Reactive

A material, other than an explosive, which in the pure state or as commercially produced, will vigorously polymerize, decompose, condense, or become self-reactive and undergo other violent chemical changes, including explosion, when exposed to heat, friction or shock, or in the absence of an inhibitor, or in the presence of contaminants or in contact with incompatible material.

Water Reactive

A material, upon exposure to water or moisture, that explodes, violently reacts, produces flammable, toxic or other hazardous gases, or evolves enough heat to cause self-ignition or ignition of nearby combustible materials.