Biological Safety

Universal Precautions

The World Health Organization (WHO) laboratory biosafety manual, produced by the Special Program on Safety Measures in Microbiology (SMM), provides internationally applicable guidance on biosafety developed by several expert working groups.

Recognizing that laboratory accidents and infections are caused primarily by poor practice and technique, the manual emphasizes safe practice and training procedures. It also presents basic standards of laboratory design for work with microorganisms by degree of infective risk and a guide to selecting and using essential biosafety equipment and materials. Although oriented to biosafety, the manual also provides a general laboratory safety checklist and safety procedures for using and handling laboratory chemicals.

The manual is intended primarily for the guidance and use of laboratory supervisors, biosafety officers, and others responsible for laboratory safety programs. The following are highlights of the universal precautions for laboratories, per the biosafety manual:

Universal precautions should apply to blood and all body fluids containing visible blood, semen, vaginal secretions, tissues, cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, and amniotic fluid.

Hands should be washed immediately when contaminated with blood or other bodily fluids, after removing gloves, and after completing laboratory activities.

Use of needles and syringes should be limited to situations in which there is no alternative. If used, needles should not be recapped, purposely bent or broken by hand, removed from disposable syringes, or otherwise manipulated by hand. After use, disposable syringes and needles, scalpel blades, or other sharp items should be placed in puncture resistant containers for disposal; these containers should be located as close as practical in the use area. Reusable sharps should be placed in a puncture-resistant container for safe transport to the processing area.

Laboratory workers should use protective barriers appropriate for the laboratory procedure and the type and extent of exposure anticipated. For example:

-- All persons processing blood should wear gloves.

-- Phlebotomists should wear gloves when they have cuts, scratches, or other breaks in the skin, when hand contamination is predictable (i.e. uncooperative patient, or heel or finger sticks on infants and children), and when receiving training in phlebotomy.

-- Surgical or examinations gloves should not be washed or disinfected for reuse.

-- General-purpose utility gloves should not be used for housekeeping, instrument cleaning, and decontamination procedures and can be decontaminated for reuse as long as they remain in tact.

-- Masks and protective eyewear or face shields should be worn if mucous membrane contact with blood or bodily fluids is anticipated (i.e., removing tops from vacuum tubes).

-- Gowns, laboratory coats, or aprons should be worn during procedures that are likely to generate splashes of blood or bodily fluids and should be removed before leaving the laboratory.

-- Routine procedures, such as histologic and pathologic studies or microbiological culturing, do not require a BSC. BSCs (Class I or II) should be used whenever procedures are conducted that have a high potential for generating droplets (i.e., blending, sonicating, and vigorous mixing.)

All specimens of blood should be put in a well-constructed container with a secure lid to prevent leakage during transport.

Mechanical pipetting devises should be used in the laboratory. Mouth-pipetting must not be performed.

Laboratory work surfaces should be cleaned of visible material and then decontaminated with an appropriate chemical germicide after a blood or bodily fluid spill and when work activities are completed.

Contaminated materials used in laboratory tests should be decontaminated before reprocessing or be placed in bags and disposed of in accordance with institutional and regulatory policies for disposal of infective waste.

Contaminated scientific equipment should be clean and then decontaminated before repair in the laboratory or transport to the manufacturer.

Area posting of warning signs should be considered to remind employees of continuing hazards of infectious disease transmission in the laboratory.