>>2912995Shooting at higher ISO does increase surface current, but it's not a real issue unless the sensor starts overheating, and even then it will primarily reduce image quality before actually becoming damaged.
If this camera has live view, keeping it turned on at a high ISO is a sure way to get it toasty, or just shooting a lot of frames non-stop. Honestly I've never seen anyone ever write about a sensor damaged from overheating, even by those who shoot video.
