Ceramic tile is a natural material, and some types of tile are made from recycled glass (including the products listed below). When buying tile (especially imported tile), just be careful not to buy tiles with lead-based or radioactive (often cobalt blue or burnt orange) glazes. Also, use non-toxic adhesives, mortars, and grouts for installing the tile.
Bent nails often result from poor hammering technique. However, they can also be caused by a dirty hammer face, especially when using cement-coated nails or working around adhesives. If you have problems, occasionally run a piece of fine sandpaper or emery cloth over the face. If you keep the face clean you will gain more solid contact with the nail and will avoid black marks on the wood caused by a dirty hammer.