There are some chemical elements that are inherently toxic and which for centuries insidiously affected human affairs by their widespread use killing scientists, poets, emperors, kings and even popes. Meanwhile less exalted people deliberately used them to dispose of unwanted individuals and, until chemical analysis became part of forensic investigation, they often murdered with impunity. Now we understand how these elements behave in the body we can reassess some famous cases more objectively, including a murder in the Tower of London. Arsenic, antimony, mercury, lead and thallium are the most infamous of these poisonous elements and all have a dark past. Indeed some continue to haunt us.

MANDEC Dental School, Higher Cambridge Street, Manchester