Laboratories routinely work with hazardous substances, but not all materials present the same level of risk. Under the Occupational Safety and Health Administration (OSHA) Occupational Exposure to Hazardous Chemicals in Laboratories Standard [29 CFR 1910.1450], commonly referred to as the Lab Standard, certain chemicals are classified as Particularly Hazardous Substances (PHSs) and require enhanced safeguards beyond routine laboratory practices.
Failure to properly identify and manage PHSs can lead to increased employee exposure risks and regulatory compliance deficiencies. Understanding what qualifies as a PHS and how OSHA expects them to be managed is a critical component of any laboratory’s Chemical Hygiene Program.
As described in the following sections, the Lab Standard identifies three categories of chemicals that are considered Particularly Hazardous Substances: select carcinogens, reproductive toxins, and substances with a high degree of acute toxicity.
Select Carcinogens
A select carcinogen is any chemical that meets one of the following criteria:
- Regulated by OSHA as a carcinogen.
- Listed as “known to be a human carcinogen” by the National Toxicology Program (NTP).
- Classified as a Group 1 (“carcinogenic to humans”) carcinogen by the International Agency for Research on Cancer (IARC).
- Classified by IARC as either a Group 2A (“probably carcinogenic to humans”) or Group 2B (“possibly carcinogenic to humans”) carcinogen, or classified by the NTP as “reasonably anticipated to be a human carcinogen” and shown to cause tumors in experimental animals at relatively low exposure levels.
Common examples include methylene chloride, benzene, formaldehyde, ethylene oxide, and cadmium compounds.
Reproductive Toxins
Reproductive toxins are substances that can adversely affect the ability to reproduce, including sexual function and fertility, as well as embryonic and fetal development. These chemicals are classified by comparing available data from both human and animal studies to the criteria found in Appendix A of the Hazard Communication Standard (HCS) [29 CFR 1910.1200].
Hexanes, toluene, N,N-dimethylformamide (DMF), and lead are examples that fall under this category.
High Degree of Acute Toxicity
According to an OSHA letter of interpretation, chemicals that are considered to have a high degree of acute toxicity are those that are highly toxic or toxic as defined by the HCS, and may be fatal or cause damage to target organs as a result of a single exposure or exposures of short duration.
Chemicals with a high degree of acute toxicity include hydrogen sulfide, certain cyanides (e.g., sodium cyanide, potassium cyanide), hydrogen fluoride, and concentrated ammonia solutions.
How Do You Determine Whether a Chemical is a PHS?
A chemical’s Safety Data Sheet (SDS) is often the best way to identify whether it may qualify as a PHS. Key sections are Section 2 (Hazard Identification) and Section 11 (Toxicological Information).
If the hazard statements noted below are found in Section 2, they may indicate that the chemical is a PHS.
- Select carcinogen: “May cause cancer” or “Suspected of causing cancer.” (The substance will be listed as either Category 1A, 1B, or 2). These hazard statements may indicate that a chemical qualifies as a select carcinogen; however, Section 11 of the SDS should be reviewed to determine whether the substance meets OSHA’s select carcinogen definition based on OSHA, IARC, or NTP classifications.
- Reproductive toxin: “May damage fertility or the unborn child.” The hazard statement “Suspected of damaging fertility or the unborn child” is also generally indicative that the chemical is classified as a reproductive toxin, but Section 11 should be referred to for supporting toxicological data. (The substance will be listed as either Category 1A, 1B, or 2.)
- Substances with a high degree of acute toxicity: “Fatal (or may be fatal) if swallowed, inhaled, or absorbed through the skin,” or “causes (or may cause) damage to a particular organ(s).” The GHS hazard class will be noted as “specific target organ toxicity – single exposure.” (The chemical will be listed as either Category 1 or Category 2.)
OSHA Requirements for PHS Management
The Lab Standard requires the Chemical Hygiene Plan to include provisions for additional employee protection when working with PHSs. OSHA specifically identifies several control measures that should be implemented as appropriate. Key management requirements are listed below.
- Develop chemical-specific procedures: Laboratories should maintain written standard operating procedures (SOPs) that address the hazards, handling requirements, engineering controls, personal protective equipment (PPE), and waste management practices for work with PHSs. These procedures are often incorporated into the Chemical Hygiene Plan.
- Establish designated areas: PHS storage and handling must be restricted to a designated area, which may be an entire laboratory, a specific room, bench, fume hood, or another defined workspace. It is recommended that designated areas be posted as such to help communicate elevated hazards and limit unnecessary exposure.
- Use appropriate containment devices: Engineering controls play a critical role in preventing exposure to PHS chemicals. Depending on the hazards involved, work may require the use of fume hoods, glove boxes, local exhaust vents, or other containment systems to minimize exposure.
- Establish decontamination procedures: Laboratories must have procedures for removing contamination from work surfaces and equipment. Areas used for PHS handling should be routinely inspected and decontaminated as necessary.
- Manage contaminated waste properly: Special procedures must be established for handling and disposing of waste from PHS use, including chemical waste, disposable PPE, and absorbent materials.
In addition to the above provisions, employees who work with PHSs must understand the specific hazards, required controls and PPE, and emergency procedures. Training should occur before work begins and whenever new hazards are introduced. These topics are often reviewed during general Chemical Hygiene Training.
Final Takeaway
Although Particularly Hazardous Substances may represent only a small portion of the chemicals maintained in a laboratory, they pose some of the most significant risks to employee health. If your lab has not recently reviewed its inventory for PHSs and addressed them in its Chemical Hygiene Plan, SOPs, and training, now is an excellent time to do so. A proactive assessment not only supports OSHA compliance but also reduces employee exposure risks and helps ensure a safer laboratory environment for everyone.
For help identifying PHSs on your facility’s chemical inventory, implementing appropriate controls, or conducting the required training, contact us.
This blog was written by Beth Graham, Director of Quality, Research, and Training at Safety Partners.
