Vision: A Resource for Writers
Holly Lisle's Vision
Poisoning Persons in Print
By Alison Sinclair
2002, Alison Sinclair
"All substances are poisons … The right dose separates a poison
from a remedy."
One of your characters has murder in mind, but is not disposed to direct
confrontation with sword, knife or morningstar, having neither the skill nor the
temperament, perhaps (the psychology of poisoners is beyond the scope of this
article). I hope in this article to hit some high points, point up some patterns
and offer some possibilities on the menu. I have tended to describe natural
poisons, because that is my interest, although the references at the end of the
article also cover chemical poisons. Partly because this is an article, not a
textbook, and partly to help inventors of poisons, I have kept to broad outlines
and general principles, though I've given examples which may be used directly or
as models for invented poisons, under four rough headings: origins of poisons,
various possibilities and patterns, how poisons cause sudden death, and
Where Does It Come From?
If a poison is from a natural source, then where it comes from will
determine its repertoire of effects.
If an animal envenoms its prey, then its venoms will make the prey easier to catch or easier to digest, or both. Any animal at a disadvantage for mobility will tend to favour paralytic venoms - neurotoxins. As an example, there are a number of species of snails that live on fish. They spear the fish with a tethered harpoon containing a paralytic venom that works almost instantaneously. Each species produces a different cocktail of venoms, tailored to its own needs. A creature that does not have teeth or a similar, effective rending apparatus may produce enzymes which pre-digest its prey prior to ingestion: In March Upcountry, John Ringo and David Weber use this to horrible effect when their marooned marines encounter a predatory alien maggot. They're stretching enzyme kinetics with the speed of action, I think, but the effect fits with the origin.
pictures for larger versions)
If an animal manufactures its venom for defense, then its poison is likely to be paralytic or extremely painful, so it will disable or deter a predators before it eats or damages the animal. Creatures which use venom for defense may be flamboyant in their colouring (left) or effectively camouflaged (stonefish).
The stonefish (left), one of the world's most poisonous fishes, has
short, thick spines which are embedded in
venom sacs. Pressure on one of those spines will compress the sac and inject the
venom. Jellyfish poisons are immediately effective and extremely painful. Given
the jellyfish's fragility, it needs to make its presence and deterrent known.
are often bacterial or plant in origin. Even animal toxins may be borrowed from
bacteria. Tetrodotoxin is the poison found in puffer fish, source of the
delicacy fugu, which when eaten in small doses causes tingling of the lips and
extremities and in large doses, paralysis and death. It has been touted as the
voodoo poison; this the experts find implausible, but it does make a good story
(see link below "Eye of Toad, Skin of Newt, Bile of Pufferfish"). The
puffer fish (left) carries tetrodotoxin in its body without ill-effect because
it has a mutation in the molecule which is the poison's site of action. However,
if a puffer fish is reared without contact with wild puffer fish, its flesh has
no poison. The poison is from a bacterial source; without contact, it cannot be
transmitted. Batrachotoxin, which has been found on the skin of some species of
toad and the feathers of a few species of bird, and is very poisonous – people
have had toxic symptoms after merely handling one of those creatures – is
another likely bacterial product.
Plants are the Borgias of the living world. Unable to run away, they wage
chemical warfare on insects, herbivores, and ruminants. Numerous plants produce
cyanide in their seeds or their young leaves, often attached to other molecules
in the form of cyanogenic glycosides, such as amygdalin (found in apricot and
cherry pits). In this form, cyanide is nontoxic to the plant; only in the
breakdown of cyanogenic glycosides, during animal consumption or digestion, is
hydrogen cyanide gas released. Plant alkaloids, organic molecules noted for
their bitter taste, include poisons which are paralytic (curare),
hallucinogenic, and cardiotoxic (atropine); they have also given rise to
medications such as the cancer drugs vinblastine and vincristine. Trees will
produce caustic or cloying sap (latex) to kill insects. And then there are the
poisons which are addressed to one particular pest: African bungleweed produces
a substance that resembles a normal hormone but that causes caterpillars to
develop into bicephalic butterflies – a lethal mutation. Milkweed contains a
poison which causes heart attacks in caterpillars. Cotton grass contains a
poison that inhibits lemmings' digestion (remember the tribbles?).
Symptoms of poisoning come in clusters which are consistent with the
organ or body system affected by the poison. Poisons which affect receptors in
the nervous system can have wide-ranging effects. "Red as a beet, blind as
a bat, mad as a hatter, dry as a bone" or alternately "can't see,
can't pee, and dammit, I drink all day," are two mnemonics medical students
acquire while learning the effects of atropine. Atropine (also known as
belladona) affects the receptors which are common to nerves which control pupil
dilatation, salivation, heartbeat, urination, and blood flow to the skin; it
also causes psychosis. Some other possible clusters of symptoms from poisons
which affect widely distributed receptors (with examples) are:
Poisons can be photoactivated: a harmless precursor can be converted into
a poison by the action of sunlight on the skin. A number of medications are
notorious for making people intolerant to sunlight. Poisons can also enhance
each others' effect: alcohol and tetrachloromethane, both poisonous to the
liver, cause far more damage in combination than could be predicted from the
separate effect of each. And what might be a harmless substance to one person
– such as a trace of peanut butter - can be lethal to someone who is severely
allergic to it (which has been used in a number of mystery novels, and requires
foreknowledge of the vulnerability).
The quickest acting poisons - those which bring about sudden death or
death within minutes - affect the cardiovascular or respiratory system, both of
which are required for the delivery of oxygen to the tissues. Next comes the
clotting system, and after that (over days) the body's detoxification systems,
the liver and kidneys, and then the bone marrow.
The heart is an electrical organ. A bundle of cells (the sinoatrial node)
in the wall of the right atrium sends out an electrical pulse through nerve
pathways that branch throughout the heart. The muscles of the heart walls
contract in response to the signal, forcing blood out into the arteries. There
are two principal mechanisms for poisoning heart action: block the electrical
signal at some point along the pathway, or desynchronize the muscles so that the
heart cannot effectively contract. Unsynchronized contraction of the atria (the
filling chambers) is problematic,
increasing the risk of stroke, but not generally fatal in itself. Unsynchronized
contraction of the ventricles is ventricular fibrillation (aka Vfib) and is
fatal within minutes.
Digoxin (foxglove, and also the drug) acts by blocking the electrical
signal. Any number of drugs and poisons can induce arrythmias - from
antiarrythmic drugs through to over-the-counter antihistamines (for people who
have a susceptibility) through to the venoms of carnivorous invertebrates.
Generally, any venom that produces paralysis in the prey could plausibly produce
Interruption of respiration is, likewise, rapidly fatal. Five minutes is
the oft-quoted limit - but brain damage occurs in less time. And it's possible
to last longer, particularly in intense cold and with good resuscitation
afterwards. But say five minutes. Any step along the pathway between nose and
mitochondria (respiratory organelles of the cell) can be interrupted. Breathing
requires nerve input and muscle effort; either can be blocked by neurotoxins.
Incidentally, paralysis need not necessarily lead to immediate loss of
consciousness. The lining of the airsacs is exquisitely thin when healthy;
poison can inflame or damage it, and that cuts down the ability of oxygen to
cross it. Hemoglobin can be blocked from carrying oxygen to the tissues (carbon
monoxide). The metabolic pathways within the cell that convert oxygen to
metabolic energy can be inhibited (cyanide).
Damage to the blood vessel wall releases small molecules that signal the
activation of a cascade of enzyme-activations - each enzyme in the sequence is
activated by the last and activates the next; this leads after multiple steps to
the formation of a clot. The process doesn't stop there; even as the clot is
being formed, it is being broken down by another enzymatic cascade. Push the
balance of the two processes towards excess clotting, and you get thrombosis of
major vessels, which Michael Crichton used in The Andromeda Strain and
James Herbert in his recent '48. Push it towards clot breakdown, or poor
clot formation, and you get
uncontrollable bleeding, hemophilia being the example familiar to most.
Dicoumarin, the poison from sweet clover, inhibits clotting. Run both processes
too fast and you get disseminated intravascular coagulation (DIC), where
microscopic clots are constantly being formed and broken down, consuming the
clotting factors and leading to uncontrollable bleeding. DIC kills people with
sepsis and hemorrhagic fever, following
massive blood loss and transfusion, and a variety of other medical catastrophes.
And snakebite: snake venoms contain powerful procoagulants and anticoagulants.
On a timescale of days, there are the fundamental detoxification and
excretion pathways of the body, the liver and kidneys. Block either of those,
and the body poisons itself with the byproducts of its own metabolism, notably
the waste products of protein metabolism. Carbohydrates can be converted to
carbon dioxide and water and exhaled, but protein metabolism, even from muscle
breakdown, produces urea, which has to be excreted through the kidneys.
Furthermore, if the kidneys shut down, water and ions can no longer be secreted
and the fine electrical balance of the body is perturbed – with fatal
consequences such as cardiac arrythmias (see above) or swelling of the brain.
Kidney failure can also be a terminal consequence of myotoxins – muscle
poisons. Widespread death of muscle releases muscle pigments, which poison the
kidneys. The liver is responsible for breaking down protein wastes and clearing
many drugs from the systems; it is also responsible for the synthesis of the
coagulation factors described above.
Finally, over the long term, there is the bone marrow, which produces the
body's supply of red and white blood cells and platelets. If the bone marrow
stops working, over a period of weeks, as the red and white cells and platelets
already circulating in the bloodstream die off, the person becomes prone to
severe bleeding, severe infection and severe anemia.
You can play around with the timing of effect by modifying the delivery
system, as, for instance, Dirk Wyle does in Pharmacology is Murder:
packaging a rapidly acting toxin in a slow-release capsule can allow an assassin
to be elsewhere at the time of death. However, a venom may not necessarily be
active as an ingested poison, since it must not only survive the rigors of
stomach acidity and digestive
enzymes, but be taken up by the cells of the intestinal mucosa.
Poisoning the Mind
There's probably no more dramatic way to affect a character than to drive
him or her insane. Psychological effects of poisons range from the subtle –
the slow mental deterioration of chronic heavy metal poisoning, for example –
to the florid – hallucinations from the psychotropic alkaloids. Since
prehistory, shamans have used hallucinogens such as mescaline, psilocybin, and
ibogaine, derived from natural products, to extend their awareness, and native
peoples have incorporated psychotropic drugs into social and religious rituals.
Ergot poisoning, from ergot mold infection of rye bread, has been offered
as the cause of mass insanity (St. Vitis' Dance, St. Anthony's Fire) in medieval
times, as an explanation for the belief in vampires and werewolves, and even for
the witches of Salem. More than to other poisons, a person's response to
psychotropic drugs and poisons is determined by their temperament and their
culture. Hallucinations caused by a psychotropic alkaloid might be interpreted
by one character as insanity, or a curse, or a visitation by demons, and by
another as a gift of the divine.
The single most useful print source I can suggest is:
Serita Deborah Stevens and Ann Klarner. Deadly Doses: A Writer's Guide
to Poisons. Writers Digest Books; ISBN: 0898793718
Michael J. Balick and Paul Allan Cox. Plants, People and Culture: The
Science of Ethnobotany. W H Freeman & Co; ISBN: 0716760274
(has a chapter on the peyote cactus, but is also a fascinating look at
natural products and material culture)
EMedicine.com, on-line textbook of emergency medicine: Toxicology http://www.emedicine.com/emerg/TOXICOLOGY.htm
The Bad Bug Book. Foodborne Pathogenic Microorganisms and Natural Toxins
Handbook from the US FDA http://www.cfsan.fda.gov/~mow/intro.html
Colorado State College of Veterinary Medicine and Biomedical Sciences
Guide to Poisonous Plants http://www.vth.colostate.edu/poisonous_plants/
Ethnobotanical Leaflets http://www.siu.edu/~ebl/
Cone Snails and Conotoxins Home Page
On tetrodotoxin. "Eye of Newt, Skin of Toad and Bile of Pufferfish"