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First, take it into a darkened room, and see if it glows; if it does, get it checked under a Geiger counter. I know that this might sound like alarmist nonsense, but, if it was painted with radium paint, and hasn't been updated, those specks on the glass could be paint particles, and, if you breathe them in, can be very nasty. The paint doesn't appear to have the classic "browning" of old radium paint, but better safe than sorry.