Working Safely with Particularly Hazardous Substances

The increased hazard risk associated with Particularly Hazardous Substances (PHS) calls for more strict operating procedures in the laboratory:

Work Habits

  • No eating, drinking, smoking, chewing of gum or tobacco, application of cosmetics or storage of utensils, food or food containers in laboratory areas where PHS are used or stored.
  • Wash your hands and arms immediately after the completion of any procedure in which a PHS has been used and when you leave the laboratory.
  • Conduct each procedure with the minimum amount of the substance, consistent with the requirements of the work.
  • Keep records of the amounts of each highly hazardous material used, the dates of use and the names of the users.
  • Fit work surfaces, including fume hoods, with a removable liner of absorbent plastic-backed paper to help contain spilled materials and to simplify subsequent cleanup and disposal.

Personal Protective Equipment

  • PHS may require more stringent use of personal protective equipment. Check the SDS for information on proper gloves, lab clothing and respiratory protection.
  • Proper personal protective equipment must be worn at all times when handling PHS.
  • Wear lab clothing that protects street clothing, such as a fully fastened lab coat or a disposable jumpsuit, when PHS are being used. Do not wear laboratory clothing used while manipulating PHS outside the laboratory area.
  • Wear disposable protective clothing when methods for decontaminating clothing are unknown or not applicable. Discard disposable gloves after each use and immediately after overt contact with a PHS.


  • Perform PHS work in a fume hood, glove box, or other form of ventilation. If the chemical may produce vapors, mists or fumes, or if the procedure may cause generation of aerosols, use of a fume hood is required.
  • A fume hood used for PHS must have an average face velocity of between 95 and 125 feet per minute. This measurement is noted on the hood survey sticker. If the hood has not been inspected within the past year, contact EHS at 8-5294 for re-inspection before using the hood.
  • Use a glove box if protection from atmospheric moisture or oxygen is needed or when a fume hood may not provide adequate protection from exposure to the substance; e.g., a protection factor of 10,000 or more is needed.
  • Highly toxic gases must be used and stored in a vented gas cabinet connected to a laboratory exhaust system. Gas feed lines operating above atmospheric pressure must use coaxial tubing.

Storage and Transportation

  • Store stock quantities of PHS in a designated storage area or cabinet with limited access. Additional storage precautions (i.e., a refrigerator, a hood, a flammable liquid storage cabinet) may be required for certain compounds based upon other properties.
  • Containers must be clearly labeled.
  • Consider double containment. Double containment means that the container will be placed inside another container that is capable of holding the contents in the event of a leak and provides a protective outer covering in the event of contamination of the primary container.
  • Store containers on trays or pans made of polyethylene or other chemically resistant material.
  • Use secondary containment when transporting PHS from one location to another to protect against spills and breakage.

Vacuum Lines and Services

  • Protect each vacuum service, including water aspirators, with an absorbent or liquid trap to prevent entry of any PHS into the system.
  • Use a seperate vacuum pump when using volatile PHS. Perform the procedure inside a fume hood.

Decontamination and Disposal

  • Decontaminate contaminated materials by procedures that decompose the PHS to produce a safe product or be removed for subsequent disposal.
  • Decontaminat all work surfaces at the end of the procedure or work day, whichever is sooner.
  • Complete plans for the handling and ultimate disposal of contaminated wastes and surplus amounts of the PHS prior to the start of any laboratory activity involving a PHS. EHS can assist in selecting the best methods available for disposal.


Stanley Howell
Sr. Program Manager
Chemical Safety

Steve Elwood
Associate Director for Laboratory Safety