What is white powder on lead? How to remove?

What is the white powdery substance that has formed on lead airgun pellets stored in an oak cabinet for 35 years? How can it be removed safely? The lead could possibly be alloyed with some antimony, the cabinet and pellets have been in a damp basement for over 35 years. The cabinet appears to be made of oak (perhaps the tannins from the oak acted on the pellets). Here is a picture of the pellets in increasing degree of "corrosion." What is the white substance and can it be safely removed? Thank you!


[![3 pairs of airgun pellets in increasing degree of "corrosion"](https://i.stack.imgur.com/XjSJz.jpg)](https://i.stack.imgur.com/XjSJz.jpg)


