Particularly Hazardous Substances

The OSHA Laboratory Standard requires that a laboratory’s Chemical Hygiene Plan include provisions for additional employee protection for work with particularly hazardous substances. A Particularly hazardous substance (PHS) is a select carcinogen, reproductive toxin, and/or a substance that has a high degree of acute toxicity.

 The use of PHSs must be described in an SOP as part of the laboratory Chemical Hygiene Plan. Using the EH&S SOP template will fulfill all requirements. If preparing your own SOP, OSHA specifies the SOP must include, where appropriate:

  • Establishment of a designated area (may be entire lab, a portion of a lab, or a device such as a fume hood)
  • Use of containment devices such as fume hoods or glove boxes
  • Procedures for safe removal of contaminate waste
  • Decontamination procedures.

While OSHA regulations specifically discuss PHSs, this does not minimize the need for performing a risk assessment and developing SOPs for other classes of chemicals, such as flammable liquids, oxidizers, pyrophoric materials, and corrosives.  Often these classes of chemicals can pose greater risk than PHSs.

In labs where few hazardous chemicals are used, the PHS requirements can provide an extra layer of scrutiny to provide safe working conditions for these classes of materials. A specific bench, fume hood, or other appropriate location can be identified as the designated area with appropriate signage to indicate the hazards, and lab occupants can be alerted to the greater hazards present through the signage and laboratory specific training. For labs with a larger variety of hazardous chemicals, it may work best to treat the entire laboratory as the designated area.

Select Carcinogens

A carcinogen commonly describes any agent that can initiate or speed the development of malignant or potentially malignant tumors, malignant neoplastic proliferation of cells, or cells that possess such materials. Many compounds have some potential for being a carcinogen. Chemical form, concentration, procedure, and routes of exposures are all factors to be considered in carcinogen risk analysis.

Carcinogens are researched by several agencies. The criteria for listing an agent substance, mixture, or exposure circumstance as a carcinogen are generally broken down into two categories: known to be a human carcinogen, or reasonably anticipated to be a human carcinogen.

The conclusions made regarding carcinogenicity in humans or experimental animals are based on scientific judgment, with consideration given to all relevant information. If you would like to learn more about the process to assess carcinogens, you can read about the criteria from the National Toxicology Program and the International Agency for Research on Cancer.

OSHA defines select carcinogens as any substance which meets one of the following criteria:

  • It is regulated by OSHA as a carcinogen. Note that a mixture shall be considered a carcinogenic hazard if it contains a component in concentrations of 0.1 percent or greater, which is considered to be a carcinogen under this section.
  • It is listed under the category, “known to be carcinogens,” in the Annual Report on Carcinogens published by the National Toxicology Program (NTP). This report includes substances “known to be human carcinogens” because there is sufficient evidence of carcino­genicity from human studies that indicate a causal relationship between exposure to the agent and human cancer. The list also includes some substances which are “reasonably anticipated to be carcinogens.”

It is listed under Group 1 (“carcinogenic to humans”), Group 2A (“probably carcinogenic to humans”) or 2B (“possibly carcinogenic to humans”) by the International Agency for Research on Cancer (IARC). The most up to date list is published on the IARC website.

Below are common examples of chemical carcinogens used in campus laboratories.

Reproductive Toxins

Reproductive toxins include any chemicals that may affect the reproductive process including those that produce chromosomal damage (mutations) as well as substances with lethal or teratogenic effects on fetuses. It also includes substances that can affect the male or female reproductive organs and the ability to reproduce.

Unfortunately, no recognized list of known human reproductive toxins exists. OSHA specifically regulates only four agents based on their reproductive toxicity:

  • dibromochloropropane (DBCP)
  • lead
  • ionizing radiation
  • ethylene oxide

The following GHS criteria would indicate a chemical likely falls under this category: chemicals with germ cell mutagenicity (category 1A, 1B, or 2) or those with reproductive toxicity (category 1A, 1B, or 2). More information on GHS classifications can be found in this Hazard Communication Guidance publication.


The following list of other potential reproductive hazards is a combination of lists extracted from the National Institute of Occupational Safety and Health (NIOSH), the State of California and the U.S. Air Force. This list is by no means comprehensive. Handle all chemicals with caution. If you are working with an unfamiliar chemical, check the Safety Data Sheet (SDS) or PubChem to determine if the chemical is considered a reproductive toxin.

Substances with a High Degree of Acute Toxicity

The OSHA Laboratory Standard does not list or define substances with a high degree of acute toxicity. The rule’s preamble describes substances with a high degree of acute toxicity as those substances that are “fatal or cause damage to target organs as a result of a single exposure or exposures of short duration.” Hydro­gen cyanide, hydrogen sulfide and nitrogen dioxide are given as examples.

Following GHS criteria, the closest parallels to these definitions are chemicals with hazards of either acute toxicity (category 1 or 2) or those with Specific target organ toxicity, single exposure (category 1 or 2). More information on GHS classifications can be found in this Hazard Communication Guidance publication.

For reference, this is the criteria used by GHS when classifying chemicals by toxicity.

To determine if you use a substance with a high degree of acute toxicity that may require additional employee protection under the OSHA Laboratory Standard, consult the SDS, the Registry of Toxic Effects of Chemical Substances (RTECS), PubChem, or contact Chemical Safety.

Example of some chemicals with a High Degree of Acute Toxicity