Laboratory Safety and Quality Management: Containment and Corrective Action
This domain tests your judgement about risk and your ability to run a documented quality system. Questions typically describe a situation such as a spill, an exposure, an out-of-specification event or a failed external quality assessment, then ask for the immediate action and the follow-up.
Core rules
- Standard precautions apply to all specimens. Personal protective equipment includes gloves, fluid-resistant gown, eye protection and, where indicated, an N95 respirator fitted by fit-testing. Hand hygiene occurs before and after glove use.
- Biological safety cabinets: Class I protects the operator only; Class II protects operator, sample and environment and is the standard for cell culture; Class III is a gas-tight glove box for BSL-4 agents.
- Risk assessment determines containment. Any procedure likely to generate aerosols (vortexing without a cap, opening a pressurised tube, centrifuging without sealed cups) requires a cabinet or sealed rotor.
- Chemical safety uses WHMIS/GHS labels and Safety Data Sheets (Sections 1-16), with Section 8 covering exposure controls and Section 4 first aid. A spill of biological material is covered with absorbent, flooded with a 1:10 dilution of household bleach (about 0.5% sodium hypochlorite), left for 10-30 minutes of contact time, then removed as biohazardous waste.
- Quality management: documented procedures under version control, competency assessment, internal quality control, external quality assessment, nonconformance and corrective/preventive action, internal audit and management review, aligned with ISO 15189.
Worked example
An external quality assessment result is returned as unacceptable for serum sodium. Reasoning sequence: first verify transcription and units, then check that the correct EQA material was reconstituted and analysed in-date, then review the instrument calibration and the ISE electrode condition, then review the QC for that run to see whether the error was random or systematic, and then check for an indirect ISE pseudohyponatraemia mechanism since EQA material is protein-based. Once the root cause is identified, a corrective action is written, effectiveness is monitored over subsequent runs, and the whole investigation is documented and reviewed at management review. Refiling the form without investigation is not acceptable.
Traps that cost marks
- Treating a needlestick as paperwork only; immediate washing, source evaluation and post-exposure prophylaxis within hours are the priorities.
- Assuming a Class I cabinet protects the sample; it does not.
- Recording training once at hire instead of performing ongoing competency assessment.
- Correcting a problem without verifying that the corrective action worked.