In high school and later as a freshman at the American University of Beirut, I learned more about lead. I was astonished to discover that lead is the end product of three series of naturally occurring radioactive elements and that lead has more than two dozen radioactive isotopes. In my sophomore year at Boston University, I learned that lead was in a gasoline additive--an organometallic compound called tetraethyl lead. I learned that lead is a major component of automobile batteries, that it was widely used in paint, and that it is used in soldering. Later, I learned that even in ancient times, some physicians believed that lead was poisonous, but it continued to be used in medicines and cosmetics until the 20th century.