Claim: Ground glass is a deadly poison.
Origins: The use of finely-ground glass secreted in food is often mooted in murder mysteries and idle gossip as an effective technique for poisoning the unwary. Simply crush some
Although the use of ground glass as a murder weapon is usually described as a method of "poisoning," the ostensible effects of the substance when employed in the fashion described above are not poisonous in the usual sense of the word (i.e., it does not bring about illness or death through chemical means): the glass supposedly works its fatal consequences by chewing up the gastrointestinal tract of the hapless victim, causing him to bleed out (in some versions, eventually spouting blood from every opening in his body). In earlier times, however, powdered glass was believed to be poison in the ordinary sense of the word (i.e., it killed through toxicity rather than by cutting up one's innards).
However you describe it, though, the bottom line is that the "ground glass in the food" killing technique just doesn't work. The primary problem is that people really don't care to eat food full of hard, gritty nuggets, and they really don't like chewing on shards of glass that cut up their mouths. So, in order to make your glassified food palatable enough for your victim to eat it, you have to grind the glass very finely. But, as
If you could get the victim to eat coarser glass, such as crushed instead of ground, the glass shards would damage the stomach and intestine and could cause bleeding . .. [but] a person would know something was wrong with the food, and if not, he would go to a doctor about the bleeding.
Even with coarser glass, the bleeding would probably not be massive or life-threatening but slow and lead to anemia and fatigue. The stools would become black from the blood, and the victim would see a doctor.
As a matter of fact, the belief in powdered glass as an effective poison remains prevalent even though doctors have been dismissing it for about two hundred years now. In 1967's The Prevalence of Nonsense, for example, we turn up the following:
Actually, ground glass is harmless. One does not suggest a diet composed entirely of ground glass; it is said to be singularly tasteless and is generally eschewed by gourmets. But if you feed it to your rival and wait to see him writhing on the floor, you'll have a long wait.
Splinters of glass, now, provide a different story. Splinters and broken sections of glass may cut the esophagus, the stomach, and the intestines, with most unpleasant consequences, including death. But it is harder to get people to accept glass splinters: they begin to get suspicious.
The belief in powdered glass as a poison may be dismissed as just another popular fallacy.
A poisoner testified in New York City, in the spring of 1916, that he first tried ground glass; finely powdered glass, however, is harmless (see 'The Traumatic Causation of Appendicitis,' by
Sir Thomas Browne dealt with this fallacy in
Sightings: In the first season of the HBO television prison drama Oz, two inmates kill another prisoner by secretly mixing crushed glass into his food until he begins to bleed from his ears and nose.
Last updated: 12 June 2014
Ackermann, A.S.E. Popular Fallacies Explained and Corrected. London: Old Westminster Press, 1923 (pp. 205-208). Lyle, D.P. Murder and Mayhem: A Doctor Answers Medical and Forensic Questions. New York: Thomas Dunne, 2003. ISBN 0-312-30945-7 (pp. 134-135). Montagu, Ashley and Edward Darling. The Prevalence of Nonsense. New York: Harper & Row, 1967 (p. 50). Thomen, Dr. August A. Doctors Don't Believe It — Why Should You? New York: Simon and Schuster, 1941 (p. 358).