Stanford University follows the categorizing of infectious agents into levels as described in Biosafety in Microbiological and Biomedical Laboratories (BMBL), 6th edition (https://www.cdc.gov/labs/BMBL.html), written and published by the Centers for Disease Control (CDC) and NIH. The BMBL describes combinations of microbiological practices, laboratory facilities, and safety equipment in combination with four biosafety levels for various agents infectious to humans. The descriptions of biosafety levels (BSL) 1 – 4 parallel those in the NIH Guidelines for research involving recombinant DNA. Biosafety levels are also described for infectious disease activities that involve laboratory animals or plants. It is important to note that the guidelines presented in the BMBL are considered minimal for containment, and will be customized as needed.
The BSL categories are divided up by risk of disease combined with availability of preventive and therapeutic treatments. The four groups are shown in Table 1. For the list of agents and their categories, see Appendix A or go to https://my.absa.org/Riskgroups.
Table 3. Biosafety level work practice requirements.
| Work Practices | BSL – 1 | BSL – 2 | BSL – 2+ | BSL – 3 |
|---|---|---|---|---|
| Public access | Not recommended | Limit access to lab while BSL – 2 work is being conducted | Restricted | Not permitted |
| Bench-top work | Permitted | Permitted only for low-risk procedures | Not permitted for biohazardous materials | Not permitted for biohazardous materials |
| Decontamination | Daily and following any spill | Daily and following any spill | Daily; immediately following work with biohazardous materials, and following any spill | Daily; immediately following work with biohazardous materials, and following any spill |
| Eating, drinking, applying lip balm, etc. | Permitted only in designated clean areas | Permitted only in approved and designated clean areas | Not permitted at any time; Food or drink may not be brought into or through lab | Not permitted at any time; Food or drink may not be brought into or through lab |
| Lab coats | Recommended | Required when work with BSL – 2 is being conducted | Required (wraparound disposable preferable) | Required (wraparound disposable required) |
| Personal Protective Equipment | Based on risk assessment | Required: Wear appropriate combinations of special protective clothing for all activities with biohazardous materials | Required: Wear appropriate combinations of special protective clothing for all activities with biohazardous materials | Required: Wear appropriate combinations of special protective clothing plus NIOSH N95 respirators or equivalent for all activities with biohazardous materials |
| Biological Safety Cabinet (BSC) | Not required | Required for all aerosol generated processes* | Required for all work with biohazardous agents | Required for all work with biohazardous agents |
| Storage Equipment | No Biohazard signs required | Biohazard signs required, all equipment must be labeled with contents | Biohazard signs required, all equipment must be labeled with contents | Biohazard signs required, all equipment must be labeled with contents |
| Physical containment | Decontaminate equipment immediately after use | Use physical containment devices during procedures that have a high potential to create aerosols* when using biohazardous material; Decontaminate immediately after use | Use physical containment devices (centrifuge safety cup, sealed centrifuge rotor) for all activities using biohazardous material; Open containers in a BSC; Decontaminate immediately after use | Use physical containment devices (centrifuge safety cup, sealed centrifuge rotor) for all activities using biohazardous material; Open containers in a BSC; Decontaminate immediately after use |
| Hand-washing facilities | Required | Required | Required (foot, elbow, or electronic activation preferable) | Required (foot, elbow, or electronic activation required) |
| Pipetting | Only mechanical device | Only mechanical device | Only mechanical device | Only mechanical device |
| HEPA-filtered vacuum lines | Recommended | Required | Required | Required |
