Laboratory Safety Manual - Chapter 07: Highly Toxic Chemicals and Select Carcinogens

Title

Laboratory Safety Manual - Chapter 07: Highly Toxic Chemicals and Select Carcinogens

Purpose

This chapter supplements previous chapters by giving specific precautions, postings, training, and protective equipment that are necessary when working with highly toxic or carcinogenic substances.

Table of Contents

1. Introduction
2. Laboratory Safety Plans
3. Facility Requirements
4. Protective Clothing
5. Use of Primary Containment Equipment
6. Use and Decontamination of Analytical Instrumentation
7. Storage, Inventory and Identification
8. Working Quantities
9. Laboratory Transport
10. Protection of Vacuum Lines
11. Packaging and Shipping
12. Decontamination
13. Disposal
14. Animal Experimentation
15. Appendix 7-A: Highly Toxic Chemicals List

I. Introduction

Highly toxic chemicals and select carcinogens require special containment practices in addition to the processes described in Chapter 6 for toxic chemicals. Highly toxic compounds have the ability to cause harmful effects, which can be local or systemic, after a single exposure. The risk of a toxic chemical can be assessed using its LD₅₀ and LC₅₀ values, the mean lethal dose or lethal concentration causing death in experimental animals. Per the Health Hazards Definitions of the OSHA Hazard Communication Standard, a substance is highly toxic if:

• the oral LD₅₀ for albino rats is less than 50 mg/kg or
• the topical LD₅₀ for albino rabbits is less than 200 mg/kg or
• the LC₅₀ in albino rats is less than 200 ppm for one hour.

Examples of highly toxic substances include hydrogen cyanide, osmium tetroxide, phosgene, sodium azide, and tetrodotoxin. For a thorough (but not exhaustive) list of highly toxic substances, refer to Appendix 7-A.

A select carcinogen is a chemical agent that causes a malignant disease or statistically increases the risk of cancer. The OSHA Laboratory Standard 29 CFR 1910.1450 defines select carcinogens as those chemicals that are:

• regulated by OSHA as carcinogens (OSHA 1910 Subpart Z);
• listed by the National Toxicology Program (NTP) as "known to be carcinogens" (data taken from biennial Report on Carcinogens, Fifteenth Edition, 2021);
• listed by the International Agency for Research on Cancer Monographs (IARC-2022) as “carcinogenic to humans” (Group 1), “probably carcinogenic to humans” (Group 2A), or “possibly carcinogenic to humans” (Group 2B)
• listed by NTP as reasonably anticipated to be carcinogens (taken from RoC, 2021) or by IARC (2022) in Group 2A (“probably carcinogenic to humans”) or in Group 2B (“possibly carcinogenic to humans”) and causes statistically significant tumor incidence in experimental animals.

Some of these compounds are common in laboratories, such as acrylamide, chloroform, carbon tetrachloride, benzene, hydrazine, and thiourea. Any chemical with a risk of causing cancer warrants careful planning and control procedures.

II. Laboratory Safety Plans

Laboratories working with highly toxic chemicals or select carcinogens must include standard operating procedures (SOPs) in the Laboratory Safety Plan (LSP) describing the hazards of the compounds, safety precautions, and emergency procedures in the event of a spill. Refer to the SOP website for more information and an SOP template that can be used to develop your own SOPs. Refer to Chapter 2 for instructions on completing an LSP. In addition to the safety practices described for use of toxic materials, several other special safety precautions are necessary for highly toxic chemicals and select carcinogens.

III. Facility Requirements

Establish a “designated area,” in which access is restricted to personnel who are aware of the hazards of the substances in use and the necessary precautions. A foot- or elbow-operated handwashing facility must be available within the work area. A hands-free eyewash facility and a shower facility other than emergency drench showers must be available unobstructed within 10 seconds (55 feet) of the hazard.

Exhaust ventilation systems are designed to maintain negative pressure within the work area (inflow of air from the corridor into the work area). The exhaust air from the work area must discharge directly to the outdoors, and clear of occupied buildings and air intakes. Exhaust air from the work area must not recirculate. The exhaust air from glove boxes must be plumbed directly into an exhaust that discharges directly outdoors or filter through high-efficiency particulate air (HEPA) and charcoal filters. Contact EHS to determine the need for and type of treatment for other primary containment equipment. Exhaust air treatment systems that remove toxic chemicals from the exhaust air by collection mechanism such as filtration or absorption must operate in a manner that permits maintenance, to avoid direct contact with the collection medium. All exhaust air from primary containment equipment must discharge directly to the outdoors and disperse clear of occupied buildings and intakes. Exhaust systems for highly toxic substances must contain engineered fail-safe mechanisms to prevent loss of containment due to utility outages.

The EHS Director (or designee) must approve the purchase and installation of any non-ducted hoods, such as Biological Safety Cabinets and ductless chemical fume hoods. Approval will be granted only in exceptional cases. For more information, see the Laboratory Ventilation Policy. Contact EHS if you have any questions or are looking to purchase a non-ducted hood.

IV. Protective Clothing

Refer to Chapter 5: Protective Clothing and Equipment

Wear a full-fastened laboratory coat or a disposable jump suit in any area where highly toxic chemicals or select carcinogens are in use. The Principal Investigator is to provide clean protective clothing weekly. You must not wear your lab coat or other additional protective clothing outside of the work area. Following an obvious exposure, decontaminate or immediately discard all clothing contaminated by highly toxic chemicals. Do not send contaminated clothing to the laundry until decontaminated. Wear appropriate gloves (Appendix 5-B) when handling toxic substances. Double gloving is recommended when handling highly toxic chemicals or select carcinogens. Discard disposable gloves after each use and immediately after known contact with a highly toxic chemical or select carcinogen.

V. Use of Primary Containment Equipment

Procedures involving volatile chemicals, and those involving solid or liquid chemicals that may result in the generation of aerosols, must occur in a laboratory hood, glove box, or other suitable containment equipment. Examples of aerosol-producing procedures include: opening of closed vessels; transfer operations; weighing; preparing feed mixtures; and the application, injection, or intubation of a chemical into experimental animals. Class II, type B biological safety cabinets are suitable for procedures involving the use of tissue culture and other biological procedures involving highly toxic chemicals, reproductive toxins, and select carcinogens. The Principal Investigator is to obtain guidance from EHS on the selection and use of Class II biological safety cabinets. For more information on biological safety cabinets, refer to Chapter 16: Biological Safety Cabinets or contact EHS for any questions. Primary containment equipment used for chemical carcinogens must display a label that says, “CAUTION – HIGHLY TOXIC CHEMICAL (or SELECT CARCINOGEN), Authorized Personnel Only.” The examples below in Figure 7.1, Figure 7.2, and Figure 7.3 are available on the EHS Safety Labels and Signage webpage for printing.

Figure 7.1. Examples of postings for storage areas or primary containment equipment where highly toxic chemicals or select carcinogens are present.

A clean bench (Chapter 16, Section IV) is a laminar flow cabinet that provides a flow of filtered air over the work service and offers product protection, not personnel protection. Highly toxic chemicals, select carcinogens, infectious material, radioactive material, and sensitizers cannot be used with a clean bench. Clean benches should have signage that is posted by the lab or EHS with the information that it does not provide personnel protection and cannot be used with the specific materials listed above (Figure 7.2).

Figure 7.2. Example posting for clean benches.

VI. Use and Decontamination of Analytical Instrumentation

Analytical instruments, when used with highly toxic chemicals and select carcinogens, must be located entirely within a laboratory hood. When this is impossible, capture the vapors or aerosols produced by these instruments through local exhaust ventilation at the site of their production. When you remove a sample from the analytical instrument, place it in a tightly plugged sample tube, or in a manner that otherwise safeguards the lab from contamination. Completely decontaminate equipment before using it again. Contact EHS if you have additional questions about equipment decontamination.

Decontamination guidelines are as follows: Safely remove, drain, or discharge chemicals from the equipment. Collect the chemicals for re-use or hazardous waste disposal. If applicable, use an inert gas or liquid to purge the chemical residues. In some cases, the rinsate might require disposal as hazardous waste. For equipment with non-permeable surfaces, decontaminate by scrubbing with warm, soapy water. For equipment that might also contain biological contamination, follow the soapy water wash by soaking with a 10% concentration of bleach solution. Rinse the equipment for the appropriate contact time of at least 10 minutes. If the equipment has a metal surface, ensure that it is rinsed or wiped down with water or an appropriate liquid afterward to prevent corrosion.

VII. Storage, Inventory and Identification

Stock quantities of highly toxic chemicals and carcinogens must be stored in designated secured storage areas. Communicate these storage areas with signs that say, CAUTION – HIGHLY TOXIC CHEMICAL (or SELECT CARCINOGEN), Authorized Personnel Only (Figure 7.1).

Label all storage vessels containing stock quantities with the following information: CAUTION – HIGHLY TOXIC CHEMICAL (or SELECT CARCINOGEN). You may use these smaller labels available at the EHS Safety Labels and Signage webpage.

VIII. Working Quantities

Keep quantities of highly toxic chemicals and carcinogens in the work area to a minimum. Quantities should not exceed the amounts normally required for use in one week. Use the label depicted in Figure 7.3 (or similar) for storage vessels containing working quantities of highly toxic chemicals or carcinogens.

Figure 7.3. Labels for storage vessels that contain highly toxic chemicals or carcinogens.

IX. Laboratory Transport

Place storage vessels containing highly toxic chemicals or carcinogens in an unbreakable outer container before transporting them from storage areas to laboratory work areas. Place contaminated materials to transfer from work areas to disposal areas in a closed plastic bag or other suitable impermeable and sealed primary container. Place the primary container in a durable outer container before transporting. Label the outer container with both the name of the substance and the warning from Figure 7.3.

X. Protection of Vacuum Lines

Each vacuum service line, including water aspirators, must be protected with an absorbent or liquid trap and a HEPA filter to prevent entry of any highly toxic chemical or carcinogen into the system. When using a volatile chemical, use a separate vacuum pump or other device placed in an appropriate laboratory hood.

XI. Packaging and Shipping

Package highly toxic chemicals and carcinogens to withstand shocks, pressure changes, and any other condition that could cause the leakage of contents during transportation. Shipments must comply with DOT and IATA regulations. These regulations state that you must receive specific training in order to ship a hazardous chemical legally. Refer to the Transporting Research Materials website for more information. Contact EHS with any questions or for other guidance on shipping and labeling.

XII. Decontamination

Highly toxic chemicals and carcinogens that have spilled out of a primary container must be inactivated in situ or absorbed by appropriate means for subsequent disposal. Contaminated materials require decontamination by procedures that decompose the chemical for immediate disposal. Write these decontamination protocols into your Laboratory Safety Plan and update the protocols as necessary. Means for ensuring adequate clean up are required, such as wipe tests or fluorescence tests.

XIII. Disposal

EHS must approve all plans for handling and disposal of contaminated wastes. You must have written procedures in the Laboratory Safety Plan, Schedule B, and you must fully describe highly toxic and carcinogenic substances in your waste stream when submitting an online hazardous materials transfer form. Refer to Chapter 12: Laboratory Waste Management Plan for additional guidance.

XIV. Animal Experimentation

Research and animal care personnel must always wear a disposable jumpsuit or lab coat, shoe coverings, hair covering, gloves, and a mask when entering Division of Comparative Medicine (DCM) animal housing facilities or procedure rooms (refer to Chapter 14: Safe Handling of Laboratory Animals). As discussed in Chapter 5, comfort masks and surgical masks are not respirators. The comfort masks and surgical masks provided in DCM facilities do not protect you from airborne exposures; instead, they protect the lab animals from your exhalations. Personnel engaged in procedures with exposure to airborne particulates contaminated with highly toxic chemicals or carcinogens must wear an appropriate respirator of N95 or higher protection, rather than a comfort mask or surgical mask. Refer to the Respiratory Protection section of Chapter 5: Protective Clothing and Equipment, for a description of respirator types. The use of primary containment may eliminate the need to wear a respirator.

EHS must approve the selection and use of respirators, and wearers are to participate in the UNC Respiratory Protection Program.

Do not wear masks or respirators outside of the animal room or procedure room. For tight-fitting cartridge respirators, dispose of used filters and decontaminate the respirator housing daily.

Appendices

• Appendix 7-A: Highly Toxic Chemicals List

Back to Chapter Six

Proceed to Chapter Eight