Minimizing Chemical Exposures in Laboratories: A Hierarchy of Controls
by Yuseph Sleem

The term “Hierarchy of Controls” refers to a system used in the field of occupational safety to prevent or minimize exposure to harmful materials that may be used in the work environment. Under this system, several levels of control are used to prevent adverse exposure. These controls are ranked based on their level of effectiveness; the most effective controls should always be used as the primary means of protecting personnel from exposures whenever feasible, before utilizing any less effective options. HControls

The hierarchy is applied in the laboratory as follows:

 Eliminate the hazard from the workplace completely, if at all possible.

Substitution: Evaluate alternatives for replacing any hazard or chemical with a substitute that is less hazardous.

Engineering Controls: Enclose or isolate the hazard, for example, by using hazardous materials inside a chemical fume hood or infectious materials inside of a biosafety cabinet, rather than on the open bench top.

Administrative Controls: Establish policies and procedures to minimize risk, for example, reducing the duration of activities to limit exposure, posting hazard signs, restricting access, training workers, and developing written standard operating procedures.

Behavior: Follow safe work practices good workplace housekeeping, and personal hygiene practices.

PPE:  Wear Personal Protective Equipment (PPE) to provide a barrier between the wearer and the hazard. PPE items include a lab coat, safety goggle, hearing protector, gloves, face shield, and footwear.

In laboratory settings, personnel should be aware of how to implement the hierarchy of controls to reduce exposure to hazards in their work environment. Personnel should identify highly toxic materials that are in use, evaluate the possibility of eliminating the use of these materials, or substitute such materials for less toxic alternatives. If these options are not feasible, the next best option is to ensure you are sufficiently protected by isolation of the hazard through effective engineering controls (e.g. glove box, fume hood, down draft hood, ventilated enclosure, etc.), and to employ administrative strategies to limit exposure. PPE should never be used as a first line of defense in preventing exposure to harmful materials. A laboratory researcher, for example, should not, as a first resort, choose to use a respirator (filtering face mask) to protect themselves from inhalation of harmful materials. By using a respirator, the wearer is not controlling the hazard at the source, but creating only a barrier between themselves and the contaminated environment, which is far less effective.

EH&S is available to assist laboratories in performing a risk assessment, inclusive of a chemical exposure assessment, to help determine how best to implement the hierarchy of controls. The Occupational Safety and Health Administration (OSHA) require that an exposure assessment be performed for specific hazardous chemicals, while it is simply best practice for other hazardous chemicals. For a comprehensive list of OSHA regulated substances and links to the relevant standards, please visit:

If you have concerns about the potential for exposure to a hazardous substance in your work environment, please contact EH&S to request an assessment by completing and submitting the Laboratory Hazard Assessment Form Form.pdf.

page 4 Page 4


Page 1 | Page 2 | Page 3 | Page 4 | Page 5 | Page 6
Go to EH&S Home Page