Practice question

Unfixed human tissues, blood, body fluids and all primary or continuous human cell lines must be manipulated under Biosafety Level 2 as stipulated by CDC/NIH Biosafety in Microbiological and Biomedical Laboratories. This requirement originates from unavoidable risk of bloodborne pathogens including HIV, HBV, HCV, HTLV and emerging viruses that may be present without clinical signs. Latent herpesviruses such as EBV and CMV also persist in donors. BSL-2 practices mandate use of Class II biological safety cabinets with HEPA-filtered laminar flow for any aerosol-generating procedures, limited laboratory access, biohazard signage, mandatory personal protective equipment including gloves and lab coats, eye protection when splashing possible, availability of autoclave for waste decontamination, and use of effective disinfectants like 10% bleach. Personnel require bloodborne pathogen training and HBV vaccination. Liquid waste is chemically disinfected. Unlike BSL-1 reserved for non-pathogenic lab strains, BSL-2 addresses moderate risk. Fixed paraffin-embedded tissues are exempt after complete fixation. Fixation with formalin inactivates most pathogens rendering samples safer for histology processing outside biosafety cabinets. This knowledge strengthens laboratory safety, protocol reproducibility, and regulatory compliance critical for translational research and clinical applications, ensuring reliable data and workforce protection.