poisoning

poisoning ‘Poison is in everything, and no thing is without poison. The dosage makes it either a poison or a remedy.’ These words are attributed to Paracelsus (1493–1541), the Renaissance scholar and physician. The words are undoubtedly true, even for common substances, such as salt or water, which under appropriate conditions can be poisonous. Modern medicines, useful and therapeutic in the prescribed doses, can be lethal when taken in excess; witness the number of suicides by overdose of sleeping pills. But these examples are not what is usually meant by poison. Poisons are agents that bring about the destruction of life when taken in small quantities. Further, if they are undetectable by their taste, smell, or colour their attractiveness as poisons is enhanced.

Poisonings can be accidental or deliberate. Accidental poisoning by plants, animals, or substances found around homes or places of work are not rare, especially among children, who may eat attractive berries from poisonous plants or mistake someone else's tablets or pills for sweets. In tropical countries, accidental poisoning from bites and stings of snakes, frogs, insects, or shellfish can be a major danger. Such areas usually have centres for the production of antidotes for the common animal poisons found there.

Deliberate poisoning on a grand scale, such as the use of poison gases in warfare is uncommon and contravenes international law. Deliberate poisoning of an individual by a poisoner has a long and fascinating history. It could be said that the most successful poisons (and poisoners) are by definition unknown, although it seems doubtful that such knowledge could remain undetected for long. All manner of means have been devised for delivering poison, the most common being to dissolve it in drink or mix it with food. Poisons that can be absorbed through the skin can be delivered through contaminated gloves or other clothing articles that make close contact with the skin. The mucous membrane lining the nose is highly vascular and a good site for absorption; poisons have been given by this route by incorporation into scents and nosegays. In fiction, at least, poison has been delivered to a victim when an envelope was licked. In an actual recent case in the UK the poison was applied to a door handle. Putting poison on one face of a carving knife blade delivers poison to the slice being cut or onto the next slice. By skilful use of such knives, which sometimes had small cavities to hold the poison on one side of the blade, a host could poison his guest victim while eating the same food. Alternatively, knives were designed where the slightest pressure on the blade caused the emergence of a poisoned barb from inside the handle. The minor prick might even go unnoticed by the victim, who would later become ill and die. Delivery of poison by manipulation of cutlery is of great antiquity and was apparently in use before Christ. In the Middle Ages the Borgias were said to have used this method.

Some poisons take a very long time to exert their lethal effect. In a remarkable case in modern times, an East European radio broadcaster working in London was, apparently accidentally, jabbed by a man carrying an umbrella while on the crowded underground railway system. The incident was soon forgotten, but in the days and weeks following the broadcaster became more and more ill, and eventually died. At post mortem a small, metallic hollow sphere that was filled with ricin was recovered. The gradual release of toxin was the cause of death. Poisons that take a long period to work offer advantages to the poisoner. He or she may be long gone and therefore unassociated with the demise of the victim; alternatively, time to create the impression of chronic illness can deceive the physician. At the other extreme, one of the most rapidly acting poisons is cyanide, acting within a few seconds; it was originally made from peach stones but now potassium cyanide is a common chemical used in many industrial processes and great care is needed to prevent accidental poisoning.

In early writings poisons were often catalogued along with drugs. The discovery of poisonous plants was attributed, by the Greeks, to the goddess Hecate, but it was the Arabs who turned poisoning into a specialist activity. Aconite was a commonly used poison, and under Roman Law it was illegal to grow the plant. It was, of course, a poisonous plant, hemlock, that gave Athens its state poison, used for the execution of Socrates.

Early European works on poisons were based on classic works of Galen, Dioscorides, and Nicander and those from Arabic sources. Petri de Abano in the fourteenth Century included mercury, copper, lapus lazuli, arsenic sublimate, litharge, nux vomica, laurel berries, and hellebore in his De Remedis Venenorum. In the Book of Venoms, 1424, Magister Sautes de Ardoynis listed arsenic, aconite, hellebore, laurel, opium, bryony, mandrake, leopard's gall, and menstrual blood. Books on poisons often gave recipes to be used, for example, for killing mad dogs or as insecticides, but clearly many recipes had more sinister purposes, ending with a comment such as ‘should kill within a day or so’.

In medieval times it was possible to hire a professional poisoner, as in Marlowe's Edward the Second. Poisoning of individuals in the Middle Ages was nearly always for political advancement or financial gain, and became such a hazard among the powerful and wealthy that they employed tasters. Other devices were to insist on drinking from Venetian glass, which was reported to explode if poison was added, or drinking from a vessel made from unicorn horn, which would neutralize the poison. Knowledge about poisons was common at this time, and detailed descriptions of poisoning appeared in literature. For example, a description of arsenic poisoning occurs in Shakespeare's King John (Act V, Scene 6) and Henry IV (Part 2, Act I, Scene 1). In an account of the history of Scotland, Macbeth's soldiers are reported to have massacred the invading Danes with belladonna (deadly nightshade).

The family most clearly connected with poisons is undoubtedly the Borgias. They arose in the fourteenth century in Spain and spread into Italy in the fifteenth and sixteenth centuries, with eleven cardinals, three popes, a queen of England, and a saint. Four members of the family are remembered for their scheming and intrigue, including murder by poison. They were two popes, Calixtus III and Alexander VI; a cardinal, Cesare Borgia; and his sister Lucrezia. Lucrezia Borgia has been cast in the role of the arch female poisoner, but the evidence for this view is thin.

Alan W. Cuthbert

See also chemical warfare; poisons.