Safety Guidelines for Biological Lab

After risk assessment and adopting a policy to prevent laboratory infections have been completed, comes the "practical" stage: executing the theoretical approach and implementing actions for "defensive working." The tools for the prevention of laboratory infection can be categorized into four groups:

  • 1. Safety procedures and techniques
  • 2. Safety equipment
  • 3. Containment laboratories
  • 4. Biological containment

A combination of the four groups acts as a barrier, providing the worker with appropriate protection, necessary for preventing laboratory acquired infections.

  • Primary barriers include all physical safety devices that prevent direct contact between the agent and the worker, such as personal protective equipment (gloves, coats, respirators, etc), biological safety cabinets or stainless steel sealed containers.
  • Secondary barriers provide an additional defense line to block the infectious agent from escaping into the environment if the primary barrier has collapsed. Secondary barriers consist of a variety of safety devices, such as the air filtration system, decontamination and sterilization systems, impermeable walls, etc.

Good Laboratory Practices (GLP)

GLP aims to minimize the occurrence of most common accidents caused by human error, poor laboratory practice, or the misuse of equipment. It consists of a set of instructions about the use of various laboratory equipment such as pipettes, bacterial loops, hypodermic needles, centrifuges and homogenizers.

These practices are based on sterile work techniques and are aimed to protect the experiment on one hand, and the worker and environment on the other hand from aerosol contamination. Examples for GLP practices are:

  • Bacteriological loops should be heated from the far end of the loop.
  • Loops must be cooled before touching the inoculum.
  • Mixing, blending and centrifuging should be done in airtight tubes.
  • The last drop from the pipette should not be blown out.
  • Lyophilized cultures should be opened wrapped in a cloth soaked with decontaminant, preferably in a biological safety cabinet.
  • Cultures should be poured slowly.
  • Needles should be wrapped before withdrawing from bottles.

GLP is based on years of experience and studying accidents and laboratory-acquired infections, and appears in the form of regulations. Understanding the rationale behind each regulation assists in implementing them.

Code of Practice (COP)

The code of practice is a listing of dos and don’ts for the most essential laboratory procedures that are basic to safe laboratory practice.

Some examples of these rules:

  • Mouth pipetting is prohibited.
  • Eating, drinking, smoking or putting on makeup are prohibited in the laboratory work area.
  • Gloves, waterproof closed shoes and laboratory gowns must be worn for procedures that may involve direct contact with infectious materials.
  • All contaminated materials should be decontaminated before disposal.
  • Work surfaces should be decontaminated at least once a day and after every spill of infectious material.
  • Thoroughly wash your hands for at least 20 seconds after any contact with an infective agent, at the end of every experiment, after removing your gloves and before leaving the lab

Protective equipment

The use of protective equipment aims to prevent laboratory-associated infections.

Systemic protective equipment:

  • Biosafety cabinet.
  • A filtration barrier, such as HEPA filter.
  • Pipetting aids

Personal protective equipment:

  • Body- fabric or disposable, fully zipped, lab coat.
  • Head- head cover, such as a surgical hat.
  • Hands- gloves, compatible for the nature of work.
    •  Nitrile or latex gloves
    • Heat resistant gloves
    • Cold resistant gloves
    • Metal mesh or leather gloves
  • Feet- full cover waterproof shoes, disposable shoe covers.
  • Eyes- goggles/face shield.
  • Respiratory protection- use of respirators should be according to the risk:
    • Inhaling powder/dust- Particulate respirators (dust mask) should be worn. These respirators only protect against particles (e.g., dust). They do not protect against gases or vapors. They are commonly known: N95 or FFP1/FFP2
    • Inhaling aerosols (droplets and particles) that contain a biological agent - N95/N99 filtering face-piece respirator provides protection by reducing the concentration of aerosols in the inhaled. The most aerosol producing procedures are sonication, centrifugation and pipetting.

HEPA filter

High Efficiency Particulate Air (HEPA) filter is a type of mechanical filter that provides a barrier to biological contamination (in biosafety cabinets, for example). The filter is made of dense micro-size caliber silica fibers, arranges in a zig-zag pattern inside a metal or wood frame. The air passing through the filter encounters a maze of fibers, intercepting air born particles of all sized (including particles <0.1micron, like viruses). The most penetrating particle size is 0.3 micron. Filter efficiency should be annually tested and exceed 99.95-99.99% for 0.3 micron particles (one filter reduces the number of particles by 4 magnitudes, 2 filters connected in a row yield a 8 magnitudes reduction etc.). Despite their high efficiency, HEPA filters traps only particles, not volatile chemicals. Therefore, work with volatile chemicals should not be performed in a biological hood.

Biological containment

The biological hood and other safety equipment described above provide a primary barrier, separating the biological agent from the worker and environment. A different approach for protecting the worker is biological containment, based on limiting the infective potential of the agent or its survival outside the lab. Biological containment relies on choosing a biological agent with reduced ability to survive outside the lab or with a narrow host range, limiting the ability of the agent to infect hosts outside the lab.

The guidelines for molecular genetics research define two levels of biological containment for prokaryotic cells:

The first level, termed HV-1(host-vector-1)/EK1 provides an intermediate level of biological containment and includes hosts, such as E.Coli K-12 (and equivalent strains), and plasmids (vectors) that are not easily transmitted, such as COL E1, PSC101, Phage-Lambda etc.

The second level, HV-1(host-vector-2)/EK2, provides a high level of biological containment and reduces the “escape” probability of a recombinant strain to <1:10-8 (under suboptimal conditions, simulating the environment outside the lab).


What to do in case of a needle stick or sharp object injury:

  • Apply pressure to the injured area (to induce bleeding), while washing with water.
  • Disinfect using the disinfectant in the first aid kit.
  • Report to the emergency center 08-934-2999.