Dear Johnny Walker,
Good news, the mouse will come to absolutely no harm...... silver is an antimicrobial* so it may even stop the mouse smelling, if it ate the box.... the ILFORD boxes are made from recycled material and then overwrapped with the nice paper, so again the mouse will will be fine, don't worry. The paper will be ruined, hard cheese as they say.
*Hence of course "born with a 'silver spoon' in your mouth", before refridgerators, the wealthy ate with silver cutlery..for a very good reason.
Regards Simon ILFORD Photo / HARMAN technology Limited