Laboratory Safety and Infection Control
Laboratory safety and infection control tests the regulatory requirements, engineering controls, and exposure procedures that protect staff. The exam favors concrete numbers and sequences: what OSHA requires, what to do in the first minutes after a needlestick, and which biosafety level applies to a given organism.
Bloodborne pathogens and standard precautions
OSHA 29 CFR 1910.1030 requires a written exposure control plan, hepatitis B vaccination offered within 10 working days of assignment, personal protective equipment, engineering controls, and post-exposure evaluation. Standard precautions apply to all blood and body fluids regardless of diagnosis. Perform hand hygiene before and after gloves; gloves never replace hand washing. Remove PPE in the correct order, treating the outermost contaminated item first, and perform hand hygiene after doffing.
Sharps and post-exposure management
Do not recap, bend, or remove needles by hand. Place sharps in rigid, puncture-resistant containers filled no more than three-quarters. After a needlestick: wash the site with soap and water, do not squeeze or scrub, report immediately, and obtain source serology. For hepatitis B, an unvaccinated exposed worker receives hepatitis B immune globulin plus the vaccine series. For HIV, post-exposure prophylaxis should start ideally within 1-2 hours and no later than 72 hours. For hepatitis C there is no prophylaxis; monitor and treat if seroconversion occurs.
Chemical, fire, and biological safety
Safety data sheets have 16 sections and must be accessible for every hazardous chemical. Formaldehyde is a carcinogen requiring ventilation and exposure monitoring. Fire classes: A for wood and paper (water), B for flammable liquids (foam or carbon dioxide), C for electrical (carbon dioxide or dry chemical), D for combustible metals. Biosafety levels: BSL-2 for most clinical work, BSL-3 for Mycobacterium tuberculosis culture, BSL-4 for Ebola and Marburg. Balance and seal centrifuge tubes; aerosols are the main hazard.
Worked example
A phlebotomist sustains a needlestick from a source known to be HIV positive with visible blood on the device. Wash the site, report within the hour, draw baseline serology, and start a three-drug PEP regimen ideally within 2 hours after risk assessment.
Traps that cost marks
- Recapping needles or mouth pipetting.
- Storing food or drink in the laboratory refrigerator.
- Assuming gloves alone are sufficient protection.
- Delaying exposure reporting past the point where PEP is effective.
- Applying the wrong fire extinguisher class to an electrical fire.