First published on 
02/01/2018 - 11:45


Particularly Hazardous Substances (PHS) are chemicals that pose a high risk to employees in the workplace. Work with these substances requires specialized training from your PI or supervisor, and customized standard operating procedures that identify designated work areas, containment devices such as fume hoods and glove boxes, procedures for decontamination, and prior approvals before work begins. View example SOPs and download a template from the Chemical SOPs page, and learn more about PHS in the UW Laboratory Safety Manual.

PHS include the following.

  • 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

EH&S flags Particularly Hazardous Chemicals in MyChem based on hazards entered in MyChem corresponding to the Fire Code and the Globally Harmonized System for Classification and Labeling. EH&S also utilized the National Institute for Occupational Safety and Health (NIOSH) List of Antineoplastic and Other Hazardous Drugs in a Healthcare Setting and the EH&S Guidance on Workplace Hazards Impacting Reproduction and Development criteria.

When viewing your chemical inventory you can look for the REG (regulatory) column. You'll find that PHS chemicals are flagged with a “P”. You may also see chemicals flagged with an “E” for an EH&S reportable chemical. EH&S reports these chemicals annually in a Tier II report to the Department of Ecology per the Emergency Planning and Community Right-to-Know Act. Certain chemicals may be flagged with a “B” and that means they are both particularly hazardous and reportable by EH&S.

The list of chemicals flagged as PHS is continually changing as new chemicals are added to UW inventories and as the knowledge about chemical hazards continues to evolve. We recommend you review Safety Data Sheets and other sources of hazard information to determine if other chemicals in your work area fall within this criteria and require these additional safeguards.


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