What Happened?
A researcher was preparing to extract bone marrow from a humanized mouse that had been infected with HIV six weeks earlier. They were working inside a Class II biosafety cabinet and wearing appropriate BSL-2+ PPE, including a disposable gown and double nitrile gloves. During the procedure, the bone splintered, and a small sliver penetrated the researcher's finger through both glove layers. The researcher removed the sliver, allowed the wound to bleed freely, removed his gloves, and washed the affected area with soap and water. His PI escorted him directly to the Occupational Health and Safety Facility, arriving within 10 minutes of the incident.
What Was The Cause?
- Immediate cause: A bone sliver generated during dissection penetrated the researcher's finger through both layers of nitrile gloves.
- Underlying causes (residual hazards, not control failures):
All the controls expected for this procedure were in place and functioned correctly. The injury occurred because bone dissection has an inherent, residual puncture hazard that standard controls do not address.
- Bone dissection inherently generates sharp, sometimes high-velocity fragments.
- Standard nitrile double gloves are not puncture-resistant against bone fragments.
- No engineering control was in place between the user's hands and the specimen during the dissection step (the BSC addresses aerosol, not penetration).
- Root cause: This is a residual hazard of bone dissection under standard BSL-2+ controls. The lab's existing sharps-injury prevention program — appropriate for the aerosol, splash, and contact hazards of humanized-mouse work — does not include puncture-resistant hand protection for bone-cutting steps. Whether this constitutes a genuine root-cause finding, or is accepted as an irreducible residual risk, is a risk-management decision the lab and its IBC/Biosafety Officer should make explicitly.
How Can Incidents Like This Be Prevented?
Evaluate alternative marrow extraction methods that avoid or reduce bone cutting:
- Centrifugation-based extraction: Crushed or perforated bones are spun inside a secondary tube, forcing marrow out without repeated cutting or flushing. This is well validated in murine long bones and eliminates most opportunities for splintering.
- Crushing with mortar and pestle inside the BSC, using a closed receptacle to contain fragments.
- Use forceps to hold the bone in place and never hold it with your fingers; this method prevents splinters from penetrating your hand; it also prevents accidental needlesticks when flushing out the bone marrow with a syringe.
- Formally recognize bone dissection as a distinct hazard category in the lab.
- Revise the SOP for bone marrow harvest to:
- Specify the tool (bone scissors/rongeurs, not general scissors) and require that it be sharp.
- Specify hand positioning; non-dominant hand out of the fragment path wherever possible; use of a clamp, forceps, or tray to stabilize bone.
- Define which marrow-extraction method is used for which assay, so the decision is not left to improvisation.
- Require a documented supervised first performance before independent work with infected animals.
- Consider puncture-resistant under-gloves (e.g., Kevlar, HPPE, or cut/puncture-rated liner gloves rated to ANSI A4+ or higher, or needlestick-resistant gloves such as those used in necropsy and autopsy work) worn under the nitrile double-glove layer during bone-cutting steps.
Resources
QUICK ACTION TIPS
Minimize exposure to biohazards:
- Wash the wound with soap and water for 15 min
- Cover the wound and seek medical attention immediately
- Report the incident to your supervisor and safety office
