Chapter 7: Biosafety Principles
Biosafety principles are used to provide safe methods for managing infectious agents in the laboratory environment where they are being handled or maintained. The purpose of biosafety principles is to reduce or eliminate exposure of laboratory workers, general public, and the outside environment to potentially biohazardous materials. The four biosafety principles are engineering controls, standard operating procedures, personal protective equipment, and administrative controls.
Engineering Controls
Engineering controls include facility design, biological safety cabinets (BSCs), enclosed containers, safety centrifuge cups, and other controls designed to minimize exposure to biological agents.
Primary Engineering Controls
Primary engineering controls are designed to protect lab personnel and the immediate environment from exposure to infectious agents. They are the most effective at minimizing exposure when workers are trained in their proper use, and the equipment is regularly inspected and maintained. BSCs are the most important primary engineering control for protection of personnel and laboratory and may also provide protection for scientific samples and reagents.
Secondary Engineering Controls
Protecting the laboratory’s external environment from exposure to biohazardous materials is accomplished by a combination of biosafety principles and facility design. Facility airflow, access control, sinks for hand washing, self- closing doors, and heat-resistant and non-porous lab benches make up some of the most important examples of secondary engineering controls.
Standard Operating Procedures (SOPs)
This document, the Biosafety in Microbiological and Biomedical Laboratories (BMBL), and the NIH Guidelines provide general requirements for working with biological agents at UM. However, because these documents cover relatively general topics, individual laboratories are required to develop laboratory-specific SOPs which cover their own specific biosafety concerns and laboratory procedures.
For example, laboratory-specific SOPs should address safe manipulation of specific organisms, specific exposure control methods, specific decontamination, and waste-handling requirements. The laboratory-specific SOPs do not need to duplicate the more general SOPs contained in this manual or the CDC/NIH documents but should serve as supplements.
SOP Template
- BSL-2 Lab Template Link: BSL-2 SOP Template.docx
Personal Protective Equipment (PPE)
Personal protective equipment (PPE) includes safety eyewear, disposable gloves, and lab coats. PPE should be complemented by wearing full-length trousers and closed-toe shoes (no sandals) in the laboratory setting.
Additional PPE such as face shields, or appropriate respiratory protection may be needed based on risk assessment. Proper clothing and PPE supplement the containment measures provided by laboratory practices and safety equipment. PPE is designed to protect laboratory workers from serious exposure to biohazardous materials and should be used in conjunction with appropriate engineering and administrative controls. At a minimum, staff must use lab coats, safety glasses, and disposable gloves whenever working in the laboratory. Personal protective equipment (PPE) must be removed and hands washed before exiting the laboratory to prevent cross-contamination between individuals and research areas.
Administrative Controls
Administrative controls are policies and procedures designed to assist with the safe handling of potentially biohazardous materials. They include training, medical surveillance, vaccinations, and access control.
Chapter 7: Biosafety Levels
Four Biosafety Levels (BSL-1,2,3,4) represent combinations of laboratory practices, techniques, safety equipment, and laboratory facilities. Each combination is specifically appropriate for the operations performed and the documented or suspected routes of transmission of the biohazardous material, as well as for the laboratory function or activity. The recommended biosafety level for an organism represents the conditions under which the agent can be ordinarily handled safely.
NIH’s Guidelines for Research Involving Recombinant or Synthetic Nucleic Acid Molecules classifies “human etiologic agents” according to their relative pathogenicity, i.e., the ability to cause disease. Agents are categorized into four risk groups (RG), which are outlined in Chapter 4.
In general, the biosafety level used matches the highest RG classification of the organisms involved. For example, work with vaccinia virus, a Risk Group 2 (RG2) agent, should be conducted at BSL-2 or higher; simultaneous work with E. coli (RG1), Epstein-Barr virus (RG2), and Mycobacterium tuberculosis (RG3) should be conducted at BSL-3.
Descriptions of biosafety levels, as well as assigned biosafety levels for specific organisms, are contained in the CDC/NIH document, Biosafety in Microbiological and Biomedical Laboratories (BMBL). The BMBL outlines four biosafety levels, summarized in the table below. Biosafety Level 2 guidelines are outlined in Appendix D.
Summary of Recommended Biosafety Levels – Adapted from BMBL 6th Ed.
| BSL | AGENTS | SPECIAL PRACTICES | PRIMARY BARRIER AND PERSONAL PROTECTIVE EQUIPMENT | FACILITIES (SECONDARY BARRIERS) |
|---|---|---|---|---|
| 1 | Well-characterized agents not known to consistently cause disease in immunocompetent adult humans and present minimal potential hazard to laboratory personnel and the environment | Standard microbiological practices | No primary barriers required; protective laboratory clothing; protective face, eyewear, as needed | Laboratory doors; sink for handwashing; laboratory bench; windows fitted with screens; lighting adequate for all activities |
| 2 | Agents associated with human disease and pose moderate hazards to personnel and the environment | Limited access; occupational medical services including medical evaluation, surveillance, and treatment, as appropriate; all procedures that may generate an aerosol or splash conducted in a BSC; decontamination process needed for laboratory equipment | BSCs or other primary containment device used for manipulations of agents that may cause splashes or aerosols; protective laboratory clothing; other PPE, including respiratory protection, as needed | Self-closing doors; sink located near exit; windows sealed or fitted with screens; autoclave available. |
| 3 | Indigenous or exotic agents; may cause serious or potentially lethal disease through the inhalation route of exposure | Access limited to those with need to enter; viable material removed from laboratory in primary and secondary containers; opened only in BSL-3 or ABSL-3 laboratories; all procedures with infectious materials performed in a BSC | BSCs for all procedures with viable agents; solid front gowns, scrubs, or coveralls; two pairs of gloves, when appropriate; protective eyewear, respiratory protection, as needed |
Physical separation from access corridors; access through two consecutive self-closing doors; hands- free sink near exit; windows are sealed; ducted air ventilation system with negative airflow into laboratory; autoclave available, preferably in Laboratory |
| 4 | Dangerous and exotic agents that pose high individual risk of aerosol-transmitted laboratory infections and life-threatening disease that are frequently fatal, for which there are no vaccines or treatments; and related agents with unknown risk of transmission | Clothing change before entry; daily inspections of essential containment and life support systems; all wastes decontaminated prior to removal from laboratory; shower on exit | BSCs for all procedures with viable agents; solid front gowns, scrubs, or coveralls; gloves; full-body, air- supplied, positive pressure suits | Entry sequence; entry through airlock with airtight doors; walls, floors, ceilings form sealed internal shell; dedicated, non-recirculating ventilation system required; double- door, pass-through autoclave required |