Biosafety Level 1 (BSL1) Guidelines: Requirements, Organisms, and BSL1 vs BSL2

A first-year MBBS student walks into a microbiology teaching lab of Patan Academy of Health Sciences for her first practical with live organisms. Before touching anything, Dr. Shreyashi asks: "What's different here compared to your biochemistry lab?" The student knows the general lab rules such as handwashing, PPE, no eating. But this is the first time she is working with a live E. coli culture, even though it is the non-pathogenic K-12 laboratory strain.

Dr. Shreyashi explains: BSL1 doesn't mean "no safety rules." It means "we work with organisms that don't cause human disease, so we don't need respirators or negative-pressure rooms, but we follow ALL the foundational rules, and then add a few specific practices for working with cultures."

That distinction "not dangerous doesn't mean not careful" is what separates a safe teaching lab from a contaminated one.

BSL-1 Overview

Educators need to be aware of the risks inherent in using microorganisms in the laboratory and must use best practices to minimize the risk to students and the community. The following guidelines are designed to encourage awareness of the risks, promote uniformity in best teaching practices, and protect the health and wellness of our students.

These guidelines are not mandatory but are designed to promote best practices in the teaching laboratory. Note that not all institutions are equipped to handle organisms in a BSL2 setting.

Work with microbes in school-level teaching (primary and secondary education), in informal education settings (e.g., science fairs, museums, science centers, camps, etc.), and in undergraduate non-microbiology laboratories would almost always be at BSL1.

Figure: Biosafety Lab Level 1 (BSL-1)

Even though organisms manipulated in a BSL1 laboratory pose a low level of risk to the community and are unlikely to cause disease in healthy adults, most of the microorganisms used in the microbiology teaching laboratory are capable of causing an infection given the appropriate circumstances. Many best practices should be adopted to minimize the risk of laboratory-acquired infections and to train students in the proper handling of microorganisms.

For the foundational safety rules that apply in any microbiology lab (including BSL1 teaching labs), see Microbiology Laboratory Safety Rules and Procedure. BSL1 guidelines build on top of those baseline practices, not instead of them.

The practices set forth in these guidelines fall into six major categories: personal protection, laboratory physical space, stock cultures, standard laboratory practices, training, and documents. For ease of use, the requirements and practices are brief. Explanatory notes, sample documents, and additional resources can be found in the appendix.

What defines BSL1, and which organisms qualify

A biosafety level is not decided by the organism alone. It is set by three things together: the risk group of the organism, the procedure being performed, and the equipment available. BSL1 covers agents that are not known to consistently cause disease in healthy adults and that present minimal potential hazard to laboratory staff and the environment (Risk Group 1).

Because the procedure counts, the same genus can sit at different levels. Streak plating Staphylococcus epidermidis is a BSL1 procedure, while pipetting Staphylococcus aureus is a BSL2 procedure. The organism's hazard changed, and so did the technique's aerosol potential, so the level changed with it.

Organisms commonly worked with at BSL1 in teaching laboratories include:

• Escherichia coli K-12 (a non-pathogenic laboratory strain; note that pathogenic strains such as E. coli O157:H7 are BSL2)
• Bacillus subtilis and Bacillus megaterium
• Micrococcus luteus
• Lactobacillus species
• Saccharomyces cerevisiae (baker's yeast)

The recurring exam trap is that "harmless" is not the definition. The definition is "not known to consistently cause disease in healthy adults." Many BSL1 organisms can still cause opportunistic infection under the wrong circumstances, which is exactly why the foundational practices below still apply.

Personal Protection Requirements in Biosafety level 1 (BSL1) teaching laboratories.

1. Wear safety goggles or safety glasses when handling liquid cultures, when performing procedures that may create a splash hazard, or when spread plating.
2. Wear closed-toe shoes that cover the top of the foot.
3. Wear gloves when the student’s hands have fresh cuts or abrasions, when staining microbes, and when handling hazardous chemicals. Gloves are not required for standard laboratory procedures if proper hand hygiene is performed. Proper hand hygiene involves thorough hand cleansing prior to and immediately after finishing handling microorganisms and any time that microbes accidentally contact the skin. Hand cleansing is performed by washing with soap and water or rubbing with an alcohol-based hand sanitizer.
4. Recommended: Wear laboratory coats.

Laboratory Physical Space Requirements for Biosafety level 1 (BSL1) teaching laboratories.

1. Require all laboratory space to include:
2. Nonporous floor, benchtops, chairs, and stools.
3. Sink for hand washing.
4. Eyewash station.
5. Lockable door to the room.
6. Follow proper pest control practices.
7. Recommended: Keep personal belongings in an area separate from the work area.
8. Recommended: Use a working and validated autoclave.

Stock Culture Requirements for Biosafety level 1 (BSL1) teaching laboratories.

1. 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.
2. Maintain documents about stock organisms, sources, and handling of stock cultures.
3. Obtain fresh stock cultures of microorganisms annually (e.g., purchased, revived from frozen stock cultures, etc.) to be certain of the source culture, minimize spontaneous mutations, and reduce contamination.

Standard Laboratory Practices for Biosafety level 1 (BSL1) teaching laboratories.

1. Wash hands after entering and before exiting the laboratory.
2. Tie back long hair.
3. Do not wear dangling jewelry.
4. Disinfect bench before and after the laboratory session with a disinfectant known to kill the organisms handled.
5. Use disinfectants according to manufacturer instructions.
6. Do not bring food, gum, drinks (including water), or water bottles into the laboratory.
7. Do not touch the face, apply cosmetics, adjust contact lenses, or bite nails.
8. Do not handle personal items (cosmetics, cell phones, calculators, pens, pencils, etc.) while in the laboratory.
9. Do not mouth pipette.
10. Label all containers clearly.
11. Keep door closed while the laboratory is in session. Laboratory director or instructor approves all personnel entering the laboratory.
12. Minimize the use of sharps. Use needles and scalpels according to appropriate guidelines and precautions.
13. Use proper transport vessels (test tube racks) for moving cultures in the laboratory, and store vessels containing cultures in a leak-proof container when work with them is complete.
14. Use leak-proof containers for storage and transport of infectious materials.
15. Arrange for proper (safe) decontamination and disposal of contaminated material (e.g., in a properly maintained and validated autoclave) or arrange for licensed waste removal in accordance with local, state, and federal guidelines.
16. Do not handle broken glass with fingers; use a dustpan and broom.
17. Notify instructor of all spills or injuries.
18. Document all injuries according to school, university, or college policy.
19. Use only institution-provided marking pens and writing instruments.
20. Teach, practice, and enforce the proper wearing and use of gloves.
21. Advise immune-compromised students (including those who are pregnant or may become pregnant) and students living with or caring for an immune-compromised individual to consult physicians to determine the appropriate level of participation in the laboratory.
22. Recommended: Keep note-taking and discussion practices separate from work with hazardous or infectious material.
23. Recommended: Use microincinerators or disposable loops rather than Bunsen burners.

Training Practices for Biosafety level 1 (BSL1) teaching laboratories.

1. Be aware that student assistants may be employees of the institution and subject to OSHA, state, and/or institutional regulations.
2. Conduct extensive initial training for instructors and student assistants to cover the safety hazards of each laboratory. The institution’s biosafety officer or microbiologist in charge of the
3. laboratories should conduct the training.
4. Conduct training for instructors whenever a new procedural change is required.
5. Conduct training for student assistants annually.
6. Require students and instructors to handle microorganisms safely and responsibly.
7. Inform students of safety precautions relevant to each exercise before beginning the exercise.
8. Emphasize to students the importance of reporting accidental spills and exposures.

Document Practices for Biosafety level 1 (BSL1) teaching laboratories.

1. Require students to sign safety agreements explaining that they have been informed about safety precautions and the hazardous nature of the organisms they will handle throughout the course.
2. Maintain student-signed safety agreements at the institution.
3. Prepare, maintain, and post proper signage.
4. Document all injuries and spills; follow school/college/university policy, if available.
5. Make Safety Data Sheets (SDS, formerly called MSDS) available at all times; follow institutional documentation guidelines regarding number of copies, availability via print or electronic form, etc.
6. Post emergency procedures and updated contact information in the laboratory.
7. Maintain and make available (e.g., in a syllabus, in a laboratory manual, or online) to all students a list of all cultures (and their sources) used in the course.

BSL1 vs BSL2 at a glance

The line most students blur is between BSL1 and BSL2. The jump is driven by the organism's risk group and by whether procedures can generate infectious aerosols.

For the complete BSL1 through BSL4 comparison, see Biosafety Level 2 (BSL2) Guidelines for Teaching Laboratories.

How to Remember

• BSL1 = "standard lab practices are enough." You don't need biosafety cabinets, respiratory protection, or fancy equipment. If you can do it on an open bench with basic handwashing and gloves, it's probably BSL1. If you need a cabinet or a respirator, it's probably higher.
• Procedural rules vs. equipment rules: BSL1 doesn't exempt you from the foundational safety rules (no eating, handwashing, proper waste disposal). What it means is you don't also need a biosafety cabinet. Both sets of rules apply.
• "Open bench" doesn't mean "anything goes." Even at BSL1, procedures that generate aerosols (centrifugation, vigorous shaking, sonication) still need containment strategies — either a sealed centrifuge cup or a BSC. Don't confuse "open bench work allowed" with "ignore aerosol risks."
• Teaching labs still follow all the basics: A first-year student in a BSL1 teaching lab still washes hands, still wears gloves, still follows no-eating rules. BSL1 is lower-risk, not no-risk.

Key Exam Facts in One Table

Where Students Get Confused

1. Confusing "BSL1 = no precautions" with "BSL1 = minimal containment equipment." You still follow all foundational safety rules (handwashing, no eating, proper waste disposal) at BSL1. What's different is you don't also need a biosafety cabinet. Both sets of rules apply.
2. Assuming "open bench" means you can ignore aerosol generation. Open-bench work is allowed at BSL1, but aerosol-generating steps (centrifugation, vortexing, sonication) still call for a containment strategy such as sealed centrifuge cups. If a procedure routinely generates infectious aerosols, that is the signal the work has crossed into BSL2 territory, where a biosafety cabinet is required. "Open bench" means "no cabinet needed for routine handling," not "aerosol risk does not exist."
3. Thinking lab coat removal rules don't matter at BSL1. Removing your coat before entering common areas is foundational safety, not a BSL-specific rule. Do it at all levels, including BSL1.
4. Misunderstanding why needle recapping is prohibited. Recapping is high-risk for needle stick injury and aerosol generation. If you must recap, the one-handed scoop technique reduces both risks. Two-handed recapping is never acceptable.
5. Not recognizing that BSL1 still applies to teaching labs. A first-year MBBS student in a practical using Bacillus subtilis is working under full BSL1 rules and foundational safety rules, not a "simpler" version. The rules are the same; the organism hazard is just lower.

References

• Byrd JJ, Emmert E, Maxwell R, Townsend H. Guidelines for Biosafety in Teaching Laboratories Version 2.0: A Revised and Updated Manual for 2019. Journal of Microbiology & Biology Education. 2019;20(3):20.3.72. doi:10.1128/jmbe.v20i3.1975
• Emmert EAB; ASM Task Committee on Laboratory Biosafety. Biosafety Guidelines for Handling Microorganisms in the Teaching Laboratory: Development and Rationale. Journal of Microbiology & Biology Education. 2013;14(1):78-83. doi:10.1128/jmbe.v14i1.531
• U.S. Department of Health and Human Services, CDC, NIH. Biosafety in Microbiological and Biomedical Laboratories (BMBL). 6th ed. Atlanta, GA: CDC; 2020.
• World Health Organization. Laboratory Biosafety Manual. 4th ed. Geneva: WHO; 2020.