Some differences may exist between french and english regulations. Lessons learned are only a translation of those of french incident and are not adapt to english regulation.
Description of incident
During a protein phosphorylation experiment involving phosphorus-32, a student became contaminated. The student was handling a vial containing a 1 GBq (30 mCi) solution of P-32. She was wearing latex gloves; the vial was slippery due to condensation and it slipped from her hands and fell down behind the Perspex (beta shielding) screen. The condensation on the vial was due to the fact that it had been removed from a refrigerator shortly before handling.
Despite the vial falling behind a screen, splashes of contamination were recorded on the nose (a drop), the laboratory coat, and the gloves.
The student quickly removed the contaminated clothing and washed her nose with soap and running water, after which contamination checks gave readings close to background.
The phosphorus-32 was diluted in 60 mL of aqueous solution, and the activity in contact with the skin was estimated to be approximately 1 MBq (30 µCi) for a period of 5 minutes at most.
A 1 MBq droplet of P-32 gives a dose rate to the skin of 1.3 Sv/hr. For a 5 minute exposure, the equivalent dose to the skin is of the order of 100 mSv.
A urine sample taken on the following day later did not reveal any significant activity.
Lessons to be learned from the incident
Vials containing a radioactive solution should be carefully handled, for example with suitable tongs to keep the vial from sliding from the handler’s gloved hands (especially when the vial comes out of a refrigerator).
It is worth noting the importance of personal protective equipment (as was worn in this case) and the correct actions taken by the contaminated person who properly adhered to the procedures to be followed in the event of contamination, namely:
- Remove and dispose of contaminated clothing as solid radioactive waste
- Rinse the contaminated areas of the skin thoroughly without rubbing
- Check for residual contamination after washing, and wash again if necessary.
This incident also demonstrates the importance of information and training that must be provided to all new students. Practical training in dealing with spills of radioactive materials are recommended.
It is also worth noting that in the event of of skin contamination, the localised (external) effective dose can be significant, and this should be considered as part of the risk assessment process.