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9.4 Guidelines for Working with Particularly Hazardous Substances

Laboratory staff should always practice good housekeeping, use engineering controls, wear proper PPE, develop and follow SOPs, and receive appropriate training when working with any chemicals. The following special guidelines should be adhered to when working with particularly hazardous substances:

  • Substitute less hazardous chemicals if possible to avoid working with particularly hazardous substances and keep exposures to a minimum. 
  • Always obtain prior approval from the Principal Investigator before ordering any particularly hazardous substances. 
  • Plan your experiment out in advance, including layout of apparatus and chemical and waste containers that are necessary. 
  • Before working with any particularly hazardous substance, review chemical resources for any special decontamination/deactivation procedures and ensure you have the appropriate spill cleanup materials and absorbent on hand. 
  • Ensure that you have the appropriate PPE, particularly gloves (check glove selection charts or contact EHS at
  • Always use the minimum quantities of chemicals necessary for the experiment. If possible, try adding buffer directly to the original container and making dilutions directly. 
  • If possible, purchase premade solutions to avoid handling powders. If you have to use powders, it is best to weigh them in a fume hood. If it is necessary to weigh outside of a fume hood (because some particles may be too light and would pose more of a hazard due to turbulent airflow) then wear a dust mask when weighing the chemical. It is advisable to surround the weighing area with wetted paper towels to facilitate cleanup. 
  •  As a measure of coworker protection when weighing out dusty materials or powders, consider waiting until other coworkers have left the room to prevent possible exposure and thoroughly clean up and decontaminate working surfaces. 
  • Whenever possible, use secondary containment, such as trays, to conduct your experiment in and for storage of particularly hazardous substances. 
  • Particularly hazardous substances should be stored by themselves in clearly marked trays or containers indicating what the hazard is i.e. “Carcinogens,” Reproductive Toxins”, etc.
  • Always practice good personal hygiene, especially frequent hand washing, even if wearing gloves. 
  • If it is necessary to use a vacuum for cleaning particularly hazardous substances, only High Efficiency Particulate Air (HEPA) filters are recommended for best capture and protection. Be aware that after cleaning up chemical powders, the vacuum bag and its contents may have to be disposed of as hazardous waste
  • Ensure information related to the experiment is included within any SOPs.