Is it bad to leave glass in your foot?

Depending on how big the glass shard is, you'll notice recurrrent sharp pain at the site, as you move or are touched. On examination, you'll find a entry wound where the glass entered (unless the wound is very old and has healed over). The area around the wound will be reddended and sensitive. When probing the wound, you'll feel a very shapr pain whenever the probe touchs the glass. Glass will show up on xray, although not very well (some glass is "leaded" -- lead is chemically bonded to the glass compound ---leaded glass is easily discernable on xrays). Glass will also show up clearly on MRI scans. As far as you human body is concerned, glass is inert, so it won't change, discolor or dissolve into your system over time.