| 0 | No chemical is without some degree of toxicity. |
| 1 | Slightly toxic material. May cause irritation, but only minor residual injury even without treatment. Recognized innocuous materials when used with responsible care. |
| 2 | Moderately toxic material. Intense or continued exposure could cause temporary incapacitation or possible residual injury unless prompt medical treatment is given. |
| 3 | Seriously toxic material. Short term exposure could cause serious temporary or residual injury even though prompt medical treatment is given. Includes known or suspect small animal carcinogens, mutagens or teratogens. |
| 4 | Highly toxic material. Very limited exposure could cause death or major injury even though prompt medical treatment is given. Includes known or suspect human carcinogens, mutagens or teratogens. |
| |
| Flammability (Red Diamond) |
| 0 | Materials which will not burn. |
| 1 | Slightly combustible. Materials that require considerable preheating before ignition can occur. This rating includes most ordinary combustible materials. |
| 2 | Combustible. Materials that must be moderately heated before ignition can occur. Including liquids having a flash point above 100 degrees F, and solids that readily give off flammable vapors. |
| 3 | Flammable. Liquids and solids that can be ignited under almost all ambient temperature conditions. Including liquids with a flash point below 73 degrees F and a boiling point above 100 degrees F, solid materials which form coarse dusts that burn rapidly without becoming explosive, materials which burn rapidly by reason of self-contained oxygen (i.e. organic peroxides), and materials which ignite spontaneously when exposed to air. |
| 4 | Extremely flammable. Materials which will rapidly vaporize at normal pressure and temperature and will burn readily. Including: gases, cryogenic materials, any liquid or gaseous material having a flash point below 73 degrees F and a boiling point below 100 degrees F, and materials which can form explosive mixtures with air. |
| |
| Reactivity
(Yellow Diamond) |
| 0 | Materials which are normally stable, even under fire conditions, and which are not reactive with water. |
| 1 | Materials which are normally stable, but which can become unstable at elevated temperatures and pressures, or which may react with water with some release of energy, but not violently. |
| 2 | Materials which in themselves are normally unstable and readily undergo violent chemical change, but do not detonate. It includes materials which may react violently with water or which may form potentially explosive mixtures with water. |
| 3 | Materials which in themselves are capable of detonation but which require a strong initiating source, or which must be heated first. This rating includes materials which are shock sensitive at elevated temperatures, and which react explosively with water without requiring heat. |
| 4 | Materials which in themselves are readily capable of detonation or explosive decomposition at normal temperatures and pressures. Includes materials which are shock sensitive at normal temperatures and pressures. |
| |
| Special Notice (White Diamond) |
| OX | Denotes materials that are oxidizing agents. These compounds give up oxygen easily, remove hydrogen from other compounds or attract negative electrons. |
| W | Denotes materials that are water reactive. These compounds undergo rapid energy releases on contact with water. |