V(a). Chemical Safety - General Principles


rev 9/2016

Chapter V, Chemical Safety, provides guidelines for the safe handling of hazardous laboratory chemicals. The OSHA Laboratory Standard defines a "hazardous chemical" as one that exhibits physical or health hazards as follows.

"Physical Hazard" - a chemical for which there is scientifically valid evidence that it is a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive) or water reactive.

"Health Hazard" - a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur...includes ...carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic (blood) system, and agents which damage the lung, skin, eyes, or mucous membranes.

Determination of the hazard of a chemical is the responsibility of the manufacturer of the chemical. Information on the hazards of a particular chemical can be found on the label, the manufacturer's Safety Data Sheet (SDS), and in reference publications listed in the Bibliography. SDS are available in the College's on-line SDS library.

The term "chemical" is used interchangeably with "hazardous chemical" throughout the text. Both refer to those chemicals defined as hazardous by OSHA as described above. The requirements outlined in Chapter V apply to the laboratory use of chemicals that could result in chemical exposure under routine or emergency situations. They do not apply to the use of chemicals when no exposure is possible. For example, the use of lead shielding for radiation protection does not result in lead exposure and, consequently, the requirements for handling lead as a reproductive toxin in V(j) do not apply.

Chapter V(a) outlines general safety guidelines that apply to all laboratory work that uses hazardous chemicals. It is followed by sections on personal protective equipment, chemical storage, and guidelines for specific chemical hazard categories. Departments or faculty members to may establish additional requirements to address hazards specific to their operations.

The attitude of those working in the laboratory is the most important factor in the safe conduct of laboratory experiments. All stages of an investigation, from design through completion, must consider safety as a guiding principle. The key to designing and carrying out safe laboratory experiments is knowledge of the potential hazards. It is the responsibility of each individual working in the laboratory to become thoroughly familiar with the hazards of the chemicals he/she is using and operations he/she is performing.

A. Controlling Sources of Exposure

All experiments must be designed and carried out to minimize chemical exposure. Source reduction, engineering controls, and protective equipment, in that order, are the three primary means of controlling exposure. The following are examples of source reduction and engineering control techniques.

Source Reduction

  • Use the least hazardous chemical that will serve the intended purpose.
  • Design experiments to use the minimum amount of chemical required.
  • Always close containers when not in use.
  • Minimize the surface area of open containers (e.g., use of flask vs. beaker).

Engineering Controls

  • Use fume hoods whenever possible.
  • Do not use fume hoods for long-term storage of equipment or chemicals (see Section V(c)-1).
  • Avoid the release of chemicals in cold rooms as they have recirculating air systems.
  • Use equipment and glassware only for its designed purpose. Never use damaged equipment or glassware.
  • If operations must be left unattended, provide for containment of hazardous chemicals in the event of equipment failure.

Protective Equipment

While minimum levels of protective equipment are required as described in Chapter V(b), it should be recognized that source reduction and engineering controls are generally more effective means of exposure control.

B. Personal Hygiene

Good personal hygiene practices are essential to minimize chemical exposure and potential injury from other hazardous conditions in the laboratory such as broken glass.

  • The storage or consumption of food or beverages, application of make-up, and smoking are prohibited in all laboratories and chemical storage areas.
  • Avoid "routine" exposures. Do not smell, taste, or mouth pipette any chemicals.
  • Always wash hands immediately upon contamination, after handling chemicals and before leaving the laboratory.
  • Long hair and loose clothing must be confined.
  • Wash contaminated clothing or lab coats separate from other clothing.
  • Closed shoes (heel and toe) with no perforations must be worn in all laboratories where hazardous chemicals, biological hazards or radiation hazards are present, in the machine shop or when using tools, and when moving heavy objects.

C. Housekeeping

Keeping the laboratory work area organized and clean is essential to safe handling of chemicals. Only the equipment and chemicals necessary for the particular procedure being performed should be kept in the work area. This is particularly important when working in a fume hood as storage of numerous containers or pieces of equipment can severely diminish the effectiveness of the hood. If several people are working in the same laboratory, requirements for space and hood access should be discussed and work areas agreed upon.

Floors and surfaces should be kept clean and spills cleaned up immediately as described in Chapter III. The entire work area should be cleaned-up at the end of each day.

D. Pets in Laboratories

Pets are not allowed in laboratories where chemical, radiation, or biological hazards are present.

E. Chemical Purchase, Receipt, Transport and Shipping

The Science Center Stockroom establishes procedures for purchase and receipt of chemicals.  Chemicals are received at the Science Center Stockroom, logged into the chemical inventory and stored for pick-up by the requisitioner.

A bottle carrier or cart must be used when moving any quantity of an acute toxin and 1 liter or greater containers of flammables or concentrated acids or bases from the stockroom to the laboratory or between laboratories. The use of a bottle carrier or cart is recommended when moving other chemicals from the stockroom to the laboratory and between laboratories.

All shipments of hazardous materials (e.g., chemicals, biological materials) from Mount Holyoke College to other locations must comply with all Department of Transportation (DOT) and International Air Transport Association (IATA) requirements. The Stockroom Manager and Chemical Hygiene Officer must approve all hazardous material shipments to ensure that they are packaged and labeled properly and that the correct documentation accompanies the shipment.

F. Chemicals Requiring Approval Prior to Purchase

There are two categories of chemical purchases that require approval prior to purchase: acute toxins as defined in Chapter V(h) and chemicals subject to Department of Homeland Security (DHS) reporting as 'chemicals of interest' that have thresholds at or below 15 pounds. Appendix V(a)-A is a compilation of the DHS List and the list of examples of Acute Toxins from Chapter V(h). Please check Chapter V(h) for the definition of an Acute Toxin to determine if a chemical meets the criteria though it may not appear on the list of examples.

To obtain approval, email Environmental Health and Safety, with a copy to the department chair, with the following information:

  • name of the chemical
  • CAS#
  • vendor and catalog #
  • amount to be purchased
  • storage location
  • brief description of use
  • date when material is needed

If approval to purchase the chemical is granted, an acute toxin protocol must be submitted as described in Chapter V(h).

G. Container Labeling

Manufacturer labels and bar codes applied by the Stockroom must not be removed or defaced. Empty containers must be cleaned before returning to the Stockroom for processing. The Stockroom provides these processed containers for reuse in the laboratory. Labels must be removed or covered and containers relabeled prior to using the container for another product or waste.

Containers into which chemicals are transferred or in which solutions are prepared must be labeled with the chemical name. Containers larger than one liter in which the chemical is to be stored must also be labeled with appropriate hazard warnings. Marking pens resistant to the contents of the container should be used, or the label should be covered with clear tape.

Unknowns for instructional use should be labeled with the hazards of the constituents, or those hazards otherwise communicated to those handling the samples. A key identifying each unknown must be kept by the responsible faculty or staff member.

H. Unattended Operations

Avoid leaving operations unattended. When it is necessary to leave an experiment unattended, provide for containment of hazardous chemicals in the event of equipment failure. Additionally, leave the lights on and place a warning sign on the door if, in the event of an emergency, there exists a hazard to persons entering the room.

I. Reporting of Unsafe Conditions

It is also the responsibility of each individual to be alert to unsafe conditions in the laboratory, take necessary actions to prevent injury (e.g., turning off faulty equipment, posting signs). All unsafe conditions, which cannot be immediately remedied, should be reported to the responsible faculty member, the Department Chair, and the Chemical Hygiene Officer.


A: Prior Authorization List -Alpha

A: Prior Authorization List -CAS#