Toxicity of a sheet of lead?
No, it is not toxic to touch solid lead.  Lead poisoning results from


ingestion: paints used to contain lead-based materials, and kids would sometimes eat the peeling paint leading to health problems.
inhalation: if you were grinding or polishing a block of lead and fine particles were generated, you might inhale them if you weren't using the proper protective equipment and health problems could develop.
dermal contact: if you were working with organic lead compounds that were easily absorbed through the skin, serious health problems would result if you weren't using the proper protective equipment.  Gasoline used to contain lead compounds, but they were removed from gasoline in order to prevent problems.


Being around or touching solid lead would not lead to ingestion, inhalation or dermal contact issues.

Here's a link to Wikipedia article on lead, see the section on "Health effects" if you'd like to read more or read about the biochemical mechanism of action.