What Happened?
A student was transferring a solution containing 1 µCi/mL tritiated (H-3) tyrosine. While opening a microfuge tube containing the solution, the tube popped free of the rack, splashing approximately 0.2 mL of the radioactive solution onto the student's face and into their eyes. At the time of the incident, the student was wearing a lab coat, gloves, and a surgical face mask, but no eye protection.
The student immediately removed her gloves and irrigated her eyes and face at the nearest eyewash station for several minutes. She then decontaminated the work area and assessed residual radioactivity by performing a swipe survey and counting the swipes with a liquid scintillation counter. She reported the incident to her PI.
A urine sample collected two days after the incident showed background radiation levels. EH&S Radiation Safety confirmed that the health risk to the student was very low: H-3 is a weak beta emitter with a maximum tissue penetration of only a few micrometers, and the estimated intake of approximately 200 nCi is less than 0.01% of the Annual Limit on Intake (80 mCi for ingested or inhaled tritiated compounds).
What Was The Cause?
- Immediate cause: A microfuge tube containing a tritiated tyrosine solution ejected from its rack when the student opened the cap, splashing approximately 0.2 mL of solution onto her unprotected face and eyes.
- Underlying causes:
- The tube was not secured against cap-opening force — the rack grip was insufficient, and no hand restraint or tube-opening tool was used.
- Eye protection was not worn; the face mask worn did not protect the eyes.
- Work was performed on the open bench rather than behind a splash shield or in a splash-controlled enclosure.
- The lab's PPE expectation for radioactive-solution work did not clearly distinguish face masks from splash-appropriate eye/face protection.
- Eyewash flush duration was below the ANSI Z358.1 15-minute standard.
- PI notification occurred after area decontamination rather than immediately after first aid.
- Root cause: Gap in the lab's SOP and PPE program for work with radioactive solutions. Specifically: (a) no requirement for splash-appropriate eye protection during any step where a capped tube is opened, a pipette is used, or a solution is transferred; (b) no engineering or technique requirement (tube-opening tool, secure rack, hand restraint on tube body, splash shield) to prevent tube ejection; (c) no clear first-aid duration standard that applies regardless of the perceived severity of the specific isotope; and (d) no clear expectation that PI/RSO notification precedes area decontamination for any radiological exposure event.
How Can Incidents Like This Be Prevented?
- Use screw-cap tubes instead of snap-cap microfuge tubes for radioactive solutions wherever the protocol allows. Screw caps release under controlled rotation rather than abrupt snap, substantially reducing ejection force and splash risk.
- Work with the lowest activity and smallest volume needed for the experiment. Reducing concentration or volume reduces the worst-case intake if a splash occurs.
- Consider substituting a non-radioactive tracer (fluorescent, stable-isotope, colorimetric) where the experimental aim permits. Tritium is often chosen by convention rather than necessity.
- Use tube-opening tools — small plastic or silicone devices that grip the tube body while opening the cap, keeping fingers off the cap, and securing the tube to the tube rack. These are inexpensive (a few dollars) and effective.
- Perform all open-tube manipulations of radioactive solutions behind a splash shield — a plexiglass benchtop shield, a plexiglass box enclosure, or within a designated radioisotope fume hood. The shield contains the splash at the source and protects the user regardless of PPE compliance.
- Use a benchtop spill tray (lipped plastic tray lined with absorbent pad) under all radioactive-solution work, so that any splash or drop is contained on the tray rather than spreading across the bench.
- Develop or revise the SOP for radioactive-solution work to specify:
- Required eye protection — safety glasses at minimum; splash goggles or a face shield for any step involving cap opening, pipetting, vortexing, centrifugation loading, or solution transfer. Make explicit that surgical/procedure masks are not eye protection.
- Tube-opening technique — use a tube-opening tool; alternatively, secure the tube body in the rack with one hand and open the cap slowly and away from the face with the other hand; do not flick the cap open while holding it in one hand.
- Splash-control expectation — work behind a splash shield or inside a hood for any open-tube radioactive manipulation; spill tray present at all times.
- First-aid response — 15-minute eyewash flush for any splash to the eyes or face, regardless of the isotope or perceived severity.
- Immediate PI/RSO notification — notify the PI and RSO immediately after first aid, and before area decontamination. Area decontamination proceeds under RSO guidance if necessary.
- Bioassay triggers — any splash involving mucous membranes, ingestion, or non-intact skin requires a bioassay regardless of activity; urine bioassay for H-3, other routes for other isotopes per RSO protocol.
- Post a first-aid / emergency-response quick-reference card at every radioactive-solution workstation covering:
- "Splash to eyes/face → eyewash 15 minutes → call PI/RSO immediately"
- "Splash to skin → wash 15 minutes → call PI/RSO"
- "Spill → step back → notify → decontaminate under RSO guidance"
Resources
QUICK ACTION TIPS
In the event of a spill on yourself:
- Wash the affected area with soap and water, then survey for radiation; do not scrub excessively
- Rinse eyes/face for 15 min at the nearest eyewash station
- Report the incident to your supervisor
In the event of a spill in the work area:
- Stop the spill
- Warn others
- Isolate the spill area
- Minimize your exposure
- Report the incident to your supervisor and RSO
