The white stuff that is on frozen vegetables is simple freezer burn.
Freezer burn on the frozen vegetables occurs when ice crystals form on the surface of the frozen vegetables when the moisture evaporates during the freezing.
The moisture evaporating during freezing of the frozen vegetables results in a dehydrated and potentially discolored patch on the frozen vegetables.
The frozen vegetables with freezer burn is safe to eat although the flavor and texture of the frozen vegetables with freezer burn will often be compromised due to the loss of moisture.
Freezer burn that occurs on other foods including meats is also safe to eat and does not harm you.
The freezer burn basically happens when the food dries out and the ice crystals that are on frozen food are created by the moisture which escaped from the frozen food.
There's no need to throw out the freezer burned food as it's still safe but sometimes it's better to use the frozen food with freezer burn in soups, stews etc where the taste and texture won't be noticed as much.
I've eaten freezer burnt food for years and although it doesn't taste as good it's still okay to eat.