What is a Particularly Hazardous Substance (PHS)?

The Occupational Health & Safety Administration (OSHA) has defined a group of chemicals as Particularly Hazardous Substances (PHS) because of their unique health hazards they present. The OSHA laboratory standard (29 CFR 1910.1450) requires, as part of the Chemical Hygiene Plan, that provisions for additional employee protection be included for all work involving a PHS.

The OSHA laboratory standard defines a PHS as select carcinogen, reproductive toxin, or substance with a high degree of acute toxicity.

Select Carcinogens are a category of chemicals where the available evidence strongly indicates that the substances cause human carcinogenicity. A “select carcinogen” meets one of the following criteria.

• It is regulated by OSHA as a carcinogen.
• It is listed under the category “known to be carcinogens” in the annual report by the National Toxicology Program (NTP).
• It is listed under Group 1 – “carcinogenic to humans” – by the International Agency for Research on Cancer (IARC)
• It is listed in either Group 2A or Group 2B by the IARC or under the category “reasonably anticipated to be carcinogens” by the NTP, and causes statistically significant tumor incidence in experimental animals in accordance with any of the following criteria:
  • After inhalation exposure of 6-7 hours per day, 5 days per week, for a significant portion of a lifetime to dosages of less than 10 mg/m³
  • After repeated skin application of less than 300 mg/kg of body weight per week; or
  • After oral dosages of less than 50 mg/kg of body weight per day.

Reproductive Toxins are chemicals that affect the reproductive capabilities including causing chromosomal damage (mutagens) and adverse effects on fetal development (teratogens).   

Substance with a high degree of Acute Toxicity are chemicals that pose a high level of immediate health risk to individuals.  They can be defined as:

• A chemical with a median lethal dose (LD50) of 50 mg or less per kg of body weight when administered orally to albino rats weighing between 200 and 300 g each.

• A chemical with a median lethal dose (LD50) of 200 mg or less per kg of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2-3 kg each. 
• A chemical that has a median lethal concentration (LC50) in air of 5000 ppm by volume or less of gas or vapor, or 50 mg per liter or less of mist, fume, or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 g each. 

How can I identify a PHS?

There is no comprehensive list of PHS, but there are different ways to determine if a chemical is a PHS.

• Review the list below for examples of a PHS.  The list is not “all inclusive.”
• Review the Safety Data Sheets (SDS), TOXNET, California-Proposition 65 List or other appropriate sources of information.
• Review a chemicals acute and chronic health effects on the SDS or other appropriate sources of information. Compare the chemical’s median lethal dose (LD50) and median lethal concentration (LC50) to those given for substances with a high degree of acute toxicity.
• For carcinogens, see if the chemical is regulated by OSHA (OSHA Carcinogen List)   as a carcinogen, or if it is listed by the  National Toxicology Program or the International Agency for Research on Cancer

What do I need to do if I have a PHS?

• Prepare a written; lab specific customized Standard Operating Procedure (SOP) for your PHS.  Refer to the Standard Operating Procedures (SOP) page for additional information. 
• Maintain a current inventory of PHS in your laboratory. CEMS is available for use at Temple University to assist with maintaining inventories.

Examples of PHS Chemicals

(Note: List is not all inclusive)

Related Information

OSHA Laboratory Safety Page

Temple University Chemical Hygiene Manual