9.4 Guidelines for Working with Particularly Hazardous Substances

Laboratory personnel should always use engineering controls, maintain good housekeeping, wear appropriate PPE, develop and follow SOPs, and complete required training when working with hazardous chemicals. The following additional precautions apply when working with Particularly Hazardous Substances (PHS), as defined by OSHA: acutely toxic chemicals, select carcinogens, and reproductive toxins.

• Substitute less hazardous chemicals whenever feasible to reduce or eliminate exposure to PHS.
• Obtain prior approval from the Principal Investigator before purchasing or using any PHS.
• Plan the experiment in advance, including workspace layout, required equipment, and waste containers.
• Review chemical safety information, including SDS Section 6 (Accidental Release Measures) and Section 13 (Disposal), and ensure appropriate spill cleanup materials and neutralizers are available.
• Select PPE appropriate for the specific chemical hazards (consult glove compatibility charts or contact EHS at askEHS@cornell.edu).
• Use the minimum quantity of PHS needed for the procedure to reduce exposure risk.
• Whenever possible, use premixed solutions to avoid handling powders. Powder handling must occur in a fume hood or ventilated balance enclosure. If engineering controls are not feasible, contact EHS—dust masks are not a substitute for respiratory protection.
• As a coworker protection measure, handle powders or dusty materials when others are not working in close proximity, and thoroughly decontaminate all work surfaces after handling.
• Use secondary containment such as trays for experiments and for chemical storage.
• Store PHS in clearly labeled, segregated areas (e.g., “Carcinogens,” “Reproductive Toxins”) consistent with the Laboratory Safety Manual and Cornell chemical storage guidelines.
• Maintain good personal hygiene, including thorough hand washing after glove removal and when leaving the laboratory.
• When vacuum assistance is required, use only vacuums equipped with HEPA filtration. Vacuum bags and filters contaminated with PHS may require disposal as hazardous waste.
• Conduct all work with PHS in a properly posted Designated Area with restricted access and clear hazard signage, as required by Cornell’s Laboratory Safety Manual.
• Ensure that all SOPs addressing the use of PHS include hazard information, designated areas, PPE requirements, waste procedures, and emergency response steps.