Lead deserves its bad reputation.  We’ve been exposed to the dangers of this heavy metal for thousands of years, from early Roman-built lead pipes to contemporary lead-based paint.  Only recently in the last half of the 20th century have scientists explained that there is no known amount of lead that is TOO small to cause some bodily harm.  Consider a fatal dose of lead when it’s fired from the barrel of a gun.

So keep your eyes open for clues to the ubiquitous nature of lead, especially if you’re in the library and Colonel Mustard is in residence.