Flammable substances are among the most common hazardous materials found in laboratories. Chemicals are generally classified as “flammable”, due to their relatively low “flashpoint”. They readily catch fire and burn in air. A flammable liquid does not itself burn; it is the vapors from the liquid that burn. The degree of fire hazard depends also on the ability to form combustible or explosive mixtures with air, the ease of ignition of these mixtures, and the relative densities of the liquid with respect to water and of the gas with respect to air.

In the laboratory, flammable liquids are those with a “flashpoint” below 100°F. Combustible liquids have a flashpoint at or above 100°F. Flammable chemicals should be stored away from all ignition sources, including open flame sources, and spark sources such as small motors or open switches. Quantities of all chemicals kept on lab benches should be limited to the amount required for a specific experiment. OSHA characterizes flammable liquids into the following categories: 

For additional information, see Section 6.4 Flammables of the CHP.

Corrosive materials present a hazard due to their ability to damage human tissue. OSHA defines corrosive material by a chemical’s ability to cause destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact, due to the chemical’s pH. The pH value of a substance represents the acidity or alkalinity of a solution. Corrosive chemicals can be found as liquids, solids, or gases. 

Major classes of corrosive substances include strong acids (e.g., sulfuric, nitric, hydrochloric, and hydrofluoric acids), strong bases (sodium hydroxide, potassium hydroxide, and ammonium hydroxide), dehydrating agents (sulfuric acid, sodium hydroxide, phosphorus pentoxide, and calcium oxide), and oxidizing agents (hydrogen peroxide, chlorine, and bromine). 

For additional information, see Section 6.2 Corrosives of the CHP.

Reactive chemicals, whether they are a pyrophoric material (a liquid or solid that will ignite spontaneously in air), water reactive, air reactive, peroxide forming or unstable in nature, must be handled with extreme care. SDSs should be carefully reviewed to verify safe handling procedures for specific chemicals/compounds. Laboratory work involving reactive chemicals should be completed in fume hoods or glove boxes.

For more information, see Section 6.6 Reactive Materials of the CHP.

Substances that pose such a significant threat to human health that they are classified as particularly hazardous substances (PHSs). The OSHA laboratory standard requires specific instructions on handling these chemicals to prevent the harmful exposure of laboratory workers to PHSs. Specialized training from your PI or supervisor, and customized standard operating procedures detailing lab specific procedures are required before work begins.

Chemicals are classified as PHSs if they belong to one or more of the following categories: 

• Highly Toxic: Chemicals in which a small dose can cause death or permanent injury or illness.
• Highly Dangerous: Chemicals that are reactive and can, for example, easily start on fire, react with the atmosphere, or explode.
• Select Carcinogens: Chemicals identified by review agencies as causing, or highly suspected of causing cancer in humans.
• Reproductive Toxins: Chemicals identified by review agencies as likely to cause harm in conceiving, bringing safely to term, or even affecting a baby after birth.
• Select Toxins: Chemicals that are potential terrorist weapons due to toxicity.

For more information, see Chapter 7 Procedures for Working with Particularly Hazardous Substances of the CHP.

Compressed gases are used in a variety of applications at Rensselaer. There are certain hazards that are inherent to compressed gases. Compressed gas hazards can be divided into two categories: physical and chemical. Understanding the properties, uses, and safety precautions before using any compressed gas cylinder is essential in keeping all laboratory workers safe.

For additional information, see Section 6.7 Compressed Gases of the CHP.