As many high schools begin adopting curricula that include the study of microorganisms, biosafety must be addressed for a safer lab experience.
Biohazards are biologically derived infectious materials, which may present a risk to other living things. Such hazards can enter the body through such places as the eyes, mouth, lungs, and open wounds. Unlike chemical hazards, biohazards can reproduce and spread infection throughout the body. Categories of biohazards include
• human, animal, and plant pathogens: bacteria, fungi, viruses, parasites, rickettsiae, chlamydiae, toxins;
• human and animal blood, blood products, tissues, and body fluids;
• cultured cells and potentially infectious agents within them;
• recombinant DNA products; and
• clinical, necropsy, and surgical specimens (e.g., tissues, fluids).
Biosafety in the lab
Biosafety protocols developed by the Center for Disease Control and Prevention (CDC) can reduce or eliminate teachers’ and students’ risk of exposure to potentially hazardous agents. The four biosafety levels (BSLs) consist of combinations of laboratory practices and techniques, safety equipment, and laboratory facilities and are specific to operations performed, transmission of infectious agents, and laboratory functions. The BSLs are described as:
• BSL1: No known or minimal potential hazard of exposure to infectious agents.
• BSL2: Moderate potential hazard with low risk of exposure to infectious agents.
• BSL3: Moderate risk of exposure to agents that can cause serious or potentially lethal disease.
• BSL4: High risk of exposure to dangerous agents that cause life-threatening disease.
K–12 science teachers should only conduct activities with BSL1-level hazards, whereas college instructors can use higher level biohazards. This designation is based on safety equipment, practices, facility design, and construction. Laboratory work using BSL1 hazards is done with defined, characterized strains and non-disease-carrying microorganisms (e.g., Bacillus subtilus, Naegleria gruberi).
Working with a BSL1-level hazard only requires handwashing after use of the biohazard. Lab work at BSL1 is generally conducted on open bench tops using standard microbiological protocol. Students must have special training in microbiological laboratory protocol, with oversight by the science teacher.
Although organisms at BSL1 pose a low risk for laboratory use, most microorganisms used in the microbiology are capable of causing an infection. To minimize the risk of infection, teachers should follow the best practices and train students in the proper handling of microorganisms.
The NSTA safety advisory board’s 2016 paper offers tips for safely handling microorganisms. In addition, the American Society for Microbiology also has guidelines for teaching biosafety in the lab. The following list summarizes these important biosafety protocols.
Personal protection requirements
• Wear indirectly vented chemical splash safety goggles when handling liquid cultures, when performing procedures that may create a splash hazard, or when spread plating (a method for isolating and enumerating microorganisms in a mixed culture and distributing it evenly on a slide).
• Wear closed-toe shoes.
• Wear gloves when the student’s hands have fresh cuts or abrasions, when staining microbes, and when handling hazardous chemicals.
• Clean hands thoroughly prior to and immediately after handling microorganisms and any time that microbes accidentally touch the skin.
• Wear laboratory coats.
Laboratory physical space requirements
• Require all laboratory space to include:
o nonporous floor, bench tops, chairs, and stools.
o sink for hand washing.
o eyewash station.
• Keep personal belongings away from the work area.
• Use a working and validated autoclave.
Stock culture requirements
• Only use cultures from authorized, commercial, or reputable sources (e.g., an academic laboratory or state health department).
• Do not subculture unknown microbes isolated from the environment because they may be organisms that require BSL2 practices and facilities.
• Obtain fresh stock cultures of microorganisms annually to be certain of the source culture, minimize spontaneous mutations, and reduce contamination.
Guidelines for biosafety in the lab
• Do not handle personal items (e.g., cosmetics, cell phones) while in the lab.
• Do not put pipette in mouth.
• Label all containers clearly.
• Keep door closed while the laboratory is in session.
• Use leak-proof containers for storage and transport of infectious materials.
• Arrange for proper decontamination and disposal of contaminated material (e.g., in a properly maintained and validated autoclave) or arrange for waste removal in accordance with local, state, and federal guidelines.
• Sweep any glass with broom and dustpan.
• Notify instructor of all spills or injuries.
• Document all injuries according to school, university, or college policy.
• Use only institution-provided marking pens and writing instruments.
• Teach, practice, and enforce the proper wearing and use of gloves.
• Advise immunocompromised students (including those who are pregnant) and students living with or caring for an immunocompromised individual to consult physicians about participation in the laboratory.
• Keep note-taking and discussion practices separate from work with hazardous or infectious material.
• Conduct extensive initial training of handling biohazards for instructors and student assistants.
• Require students and instructors to safely and responsibly handle microorganisms.
• Inform students of safety precautions relevant to each exercise.
• Emphasize to students the importance of reporting accidental spills and exposures.
• Require students to sign safety agreements about the hazards of the organisms they will handle throughout the course.
• Maintain student-signed safety agreements at the institution.
• Prepare, maintain, and post proper signage.
• Document all injuries and spills. Follow the school’s policy, if available.
• Make Safety Data Sheets available at all times. Follow institutional documentation guidelines regarding number of copies.
• Post emergency procedures and updated contact information in the laboratory.
• Maintain and make available (e.g., in a syllabus, laboratory manual, or online) to all students a list of all cultures (and their sources) used in the course.
Blood borne pathogens
The Occupational Safety and Health Administration (29 CFR 1910.1030) requires employers to have an exposure control plan in place if exposure to blood borne pathogens is likely. Blood borne pathogens include viruses, bacteria, and parasites present in blood or other body fluids. Students can be exposed to the pathogens via laboratory work. For the high school science laboratory, an exposure control plan must be in place.