There is a great article put out by the curator of the US Navy Museum put out a few years ago regarding lead corrosion within their collection of ship models.
http://www.dt.navy.mil/cnsm/lead_01.html
It's an interesting read, but the short version is that a lot of home construction type materials can cause complete corrosion of lead, and turn it to powder in just a few years. The biggest culprit is actually wood of all things, due to the release of acetic acids. And once the reaction starts, it's self-sustaining.
