That's the point ... metal can be a safety concern, especially in an arc flash situation.
When you see an arc flash video, all those sparkling bits are droplets of molten metal. The metal need not be jewelry .... even zipperz, belt buckles, and eyeglass frames contribute to the liquid shrapnel.
Some 'body' metal you can't do anything about ... like braces and dental fillings. I'd wager that the earings can be left in the locker, though.
Nor does the "oops" episode need to be dramatic. If you've ever ruined a pair of cutters by cutting into a live wire ... take a close look at the cutters. It's likely you'll find little droplets of copper fused into the steel of the tool at some distance from the new notch in the cutting edge.
