Question 1 · Hard
During a clear-out of the histology storeroom, a technician finds a 100 g bottle of picric acid at the back of a cupboard; its label shows it was bought more than 10 years ago. The laboratory once used it to make Bouin solution. The label and the safety data sheet state that it must be kept wetted with water, because the dry solid is a shock- and friction-sensitive explosive that also forms sensitive picrate salts with metals. The contents look dry, and yellow crystals have formed in the threads of the screw cap. What should the technician do?
- ARinse the crystals off the cap threads with water
- BLeave it undisturbed and call the hazardous waste team
- CSend it out with the routine chemical waste collection
- DOpen it carefully and add water to rewet the contents
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Answer: B · Leave it undisturbed and call the hazardous waste team
When picric acid dries out it becomes sensitive to shock, heat and friction, and crystals in the threads of a cap can detonate from the friction of unscrewing it. The bottle must therefore not be opened, moved or rinsed: the area is cleared and secured, and the institution's hazardous materials service, or bomb disposal if the service advises, makes it safe. Adding water is how a bottle without dry crystals at the cap is maintained, but here opening is the danger. To prevent this, picric acid stocks are kept small, dated, checked regularly and kept wet.
- A: Handling and wetting the cap still applies friction and shock to the crystals.
- C: Routine waste staff and transport are not prepared for an unstable explosive.
- D: Unscrewing the cap can detonate the dry crystals in its threads.