Don't use it. If you are sanding an older piece of furniture, you will also need to make sure the old paint was not lead-based. If you are unsure, it is a good idea to still take the proper precautions as if it were. Experts recommend sanding lead-based paint by hand with a wet sanding method and while wearing a high-quality, properly-fitted respirator. In addition, you'll want to make sure any lead dust is contained in the project area with the use of tarps and vacuums with HEPA filters. Lead can be toxic to humans, especially to children and pregnant women. Exposure to lead during pregnancy can cause everything from miscarriage to kidney issues.