Most houses in the U.S. built prior to a few decades ago have lead paint and many have asbestos. Then there&#x27;s the whole leaded gasoline fiasco.<p>The world has known of the danger of lead and many other dangerous substances, but often still chooses to use the dangerous substance.<p>Sometimes it&#x27;s because there weren&#x27;t alternative substances that could do what needed to be done. Sometimes it was just a matter of expense. Sometimes it&#x27;s because the dangerous substance was supposed to be used in a safe fashion, however reality proved the safe fashion to be overly optimistic.<p>Course, then there are cases like the leaded gasoline that should be considered one of the greatest crimes of all time.