"What is there that is not poison, all things are poison and nothing
(is) without poison. Solely the dose determines that a thing is not a
poison."
Paracelsus (1493 - 1541)

Poisonings:
Poisoning is damage to tissues by a chemical agent. Virtually anything
can act as a poison providing the quantity is sufficient.
Most poisoning cases are accidental but a large number are deliberate.
Suicidal poisoning is probably the most common method of self-
destruction. Corrosive agents (strong acids or alkalis) are used
rarely because less painful substances are available.

Homicide by poison is rare nowadays. Such weapons of the old fashioned
poisoner as arsenic, strychnine or cyanide are so easily detected that
they are rarely used nowadays.

A few people would probably wonder: "How much? Is there an exact dose
that kills?" There is no such dose. Last year there was a case of
survival from a lethal blood concentration of cyanide (the patient had
ingested ~ 1250 mg of cyanide salt, this being 5 times the amount of
the lethal dose) with associated alcohol intoxication (270 mg/dl). In
this case the presence of alcohol may have limited the uptake of the
poison by the stomach. Hydrochloric acid in the stomach causes the
release of liquid hydrogen cyanide, which is rapidly absorbed. The
alcohol might have neutralised this acid thus limiting the absorption.
On the other hand the amount of poison ingested was great. This
patient may also have been able to detoxify himself by metabolising
the cyanide to the non-toxic form, thiocyanate.

Different people will have different sensitivity and resistance to a
particular substance; even the same person may react differently in
various circumstances. The pathologist evaluating toxicology results
must not forget about tolerance. It can develop within a couple of
weeks. With substances such as benzodiazepines or morphine-heroin-
methadone group an extremely high level of a substance in the blood
does not necessary mean that the death was a consequence of the intake
of this drug. On the other hand there is idiosyncrasy, when
penicillin, aspirin or cocaine in abnormally small amounts may cause
fatal effects.

There is of course a toxicological range within which most severe
effects and deaths will lie but we should not forget that this data is
accumulated from autopsies and that post-mortem distribution of the
toxic substances is not uniform. The drug concentration in the
peripheral vessels after death can be quite different from the same in
the heart or visceral blood. Arterial and venous bloods usually
contain different concentrations of a substance because of the uptake
by the tissues. It is difficult to calculate from a post-mortem drug
concentration a total dose taken and when it was done.

Sometimes poisoning is difficult to recognise but there are signs and
symptoms that may cause a doctor to think about poisoning. They are:

Sudden vomiting and diarrhoea
Unexplained coma in children and adults known to have depressive
illness
Rapid onset of a peripheral neuropathy
Rapid onset of neurological or gastrointestinal illness in persons
occupationally exposed to chemicals
If the poisoning is suspected there are certain samples that can be
collected for toxicological analysis.
Blood - this should be obtained from blood vessels and not from body
cavities as it is almost certainly contaminated with other body
fluids. The femoral vein is probably the best site for collection of
the blood but internal jugular vein could also be used. About 30 ml of
blood is fixated and taken for toxicological analysis.

Urine - up to 30 ml is taken by suprapubic puncture with a long needle
or through an incision in the bladder.

Bile - can be useful for morphine and chlorpromazine analyses because
these substances are concentrated by the liver and excreted into the
gall bladder. This is collected directly into a bottle.

Stomach contents - at least 250 ml need to be collected. Then the
stomach is opened fully and any capsule, tablets or powder picked off.
The gastric lining also has to be examined and a part of the stomach
wall dissected off.

Intestinal contents - the intact gut is sent to the laboratory in the
case of suspected heavy metals poisoning (arsenic or antimony).

Body tissues - when the toxic substance may have been injected into
muscle. In this case the site (several centimetres in diameter) around
the puncture mark is excised, though sometimes this is hard to find!
In the United States a husband was convicted for the murder of his
wife because a poison was identified around the puncture mark in the
buttock of an exhumed body.

The shorter the delay between the time of death and the collection of
samples the better. Some poisons will form stable compounds in the
body; the processes of decomposition however will quickly break down
other substances.

All the samples must be labelled and identified and the time and
nature of the sample recorded in the medical notes as well as the name
of the person delivering the samples to the laboratory (in a criminal
case - a police officer). This is called "establishing continuity of
evidence" and may be needed if the authenticity of the analysis is
challenged in court.

COMMON POISONS AND DRUGS

No one would ever know what was the first poison used but as far back
as 2500 BC the Sumerians worshiped a goddess of poisons called "Gula".
The Egyptians have used the seed kernel of the peach, which can
release toxic cyanide compounds in the presence of water and the plant
enzyme. The words that today denote poison come from the word
"toxicon" (in Greek a bow that was used to shoot poisoned arrows at
the enemy). The Greeks also have developed the poison made from
"Poison Hemlock". This plant contains "Coniine" (a very poisonous
substance) and it was used to execute the philosopher Socrates.

Nowadays a whole array of poisons exists that was unknown to the
ancients but a lot of the poisons used in those times have been
forgotten.

DRUGS OF DEPENDENCE

Opiate drugs (heroin, morphine, methadone, and dihydrocodeine) are
commonly used and their lethal effect is usually a consequence of an
overdose or hypersensitivity. The signs of the opioid toxicity include
sweating, pinpoint pupils, slow breathing and low blood pressure. If
the dose is high it all may end in the respiratory arrest. The common
autopsy finding in a case of heroin death is severe pulmonary oedema,
from a sudden ventricular fibrillation.

Amphetamines(dextramphetamine, Benzidrene and MDMA also known as
"Ecstasy") have a strong stimulating effect but can lead to
hyperpyrexia and hypertension that may precipitate a cerebral
haemorrhage and cardiac arrhythmias.

Cocaine produces hypertension (that might lead to the cerebral
bleeding) dilated pupils and hyperpyrexia; the death may occur as a
result of respiratory depression or arrhythmia. In some cases
ulceration of the nasal septum may be seen as a result of long-term
inhalation of the drug.

MEDICINAL SUBSTANCES

Usually in a case of poisoning with a medicinal drug the autopsy
findings are unhelpful because the substances are rarely corrosive and
no local lesions are likely to be found.

Analgesicsinclude paracetamol, aspirin, amidopyrine and others. An
aspirinoverdose usually leads to vomiting thus removing much of the
drug from the body. In case the overdose is retained the symptoms are
faintness, sweating, ringing in the ears. There may be
hyperventilation, acid-base disturbance and coma. The victim might die
a sudden death or suffer cardiac arrhythmias even a couple of days
after the suicide.

At autopsy multiple haemorrhagic lesions can be seen in the gut as
aspirin is a potent anticoagulant and tablets in close contact can
erode the stomach mucosa.

Paracetamol acts by damaging the liver but if large quantities are
swallowed this can also affect brain stem thus causing death. Most
Paracetamol deaths are delayed for several days when liver failure
occurs. At autopsy, liver damage and sometimes renal tubular necrosis
may be the only findings.

Insulin - has been used both for homicide and suicide. This is a
potent agent causing hypoglycaemia, which if prolonged causes brain
damage and death. In massive intravenous doses death can take place in
a couple of hours. However insulin suicide carries the risk of
survival with hypoglycaemic brain damage.

In a case of poisoning subcutaneous tissue and muscle are analysed.
Blood samples are also taken as modern methods can distinguish between
human and animal origin of the insulin. However most of therapeutic
insulin is human nowadays and this test may become redundant.

CORROSIVE POISONS

These are strong mineral acids (hydrochloric, nitric and sulphuric),
organic acids (acetic, oxalic), alkalis (caustic soda), household
bleaches, detergents and vinegar.

Though rare in Western society as a method of self-destruction they
still are used sometimes. Their action is to irritate and destroy the
surface in which they come in contact. The way in which the poison was
administered can be reconstructed from the overflow marks and
dribbles. If they run down the chin, neck and chest the chances are
the poison was taken while sitting or standing. If the victim was
lying down or fell immediately afterwards, the trickle marks run down
the side of the face, cheeks and on to the side of the neck.

The oral cavity, pharynx and gastric mucosa may be discoloured, eroded
and even perforated (perforation of the oesophagus and stomach is most
common with sulphuric and hydrochloric acids). There may be gastric
haemorrhage. The mucosa is thickened and corroded after a contact with
acid; alkalis on the other hand turn the lining into a slimy pulp.

HEAVY METALS

This is a group of poisonous substances that was popular with
murderers in the past such as Madeleine Smith in 1857 who killed her
lover and Mary Blandy who murdered her own father in 1752.

Arsenic as the metal itself is not poisonous but its salts, called
arsenites, are. White arsenic powder is highly soluble in hot liquids;
it is almost tasteless, colourless and odourless in solution. Arsenic
is still used in agriculture (sheep-dips) and industry but weed-
killers and flypapers that used to contain enormous amounts of arsenic
are unlikely to be poisonous nowadays.

There are differences in acute and chronic arsenical poisoning. Acute
poisoning mimics cholera; there are signs of gastro-enteritis with
abdominal pain, vomiting and diarrhoea, often blood-streaked.
Dehydration and electrolyte imbalance lead to cardiovascular failure
and death. The victim of chronic poisoningmay be suspected of
suffering from some wasting systemic illness. The symptoms are the
loss of appetite and weight, anaemia, mild nausea and skin changes,
which are probably, more specific. Chronic arsenical poisoning causes
a hyperkeratosis of the palms of hands, "raindrop" skin pigmentation,
brittle nails and loss of hair.

At autopsy, in acute deaths only haemorrhagic gastritis can be found.
The stomach mucosa is oedematous with bleeding along the top ridges of
the folds ('red velvet' mucosa). In chronic poisoning there are
degenerative changes in the liver, myocardium and the kidneys, stomach
may show the signs of a chronic gastritis with excess mucus and patchy
erosion. Arsenical poisoning could be detected even long time after
death because arsenic would remain in the hair and nails for a
considerable period.

Thallium is a rat poison and a notorious poisoner Graham Young in 1971
used it to murder two of his co-workers. This Englishman began his
career as a poisoner at an age of 11 when his father presented him
with a chemistry set. Graham's stepmother died when he was 14 but no
suspicions were aroused. Later on various toxic substances and
literature on poisons was found in his room and Graham was sent to
Broadmoor Criminal Lunatic Asylum. Nine years later he was released
and began poisoning people again, now at work. However he drew
attention to himself by exposing his knowledge of toxicology, his past
was revealed and he was arrested. In prison he told about the murder
of his stepmother and was sentenced to life in prison where he died in
1990 aged 42.

Thallium poisoning acutely produces abdominal pains and vomiting then
appear confusion, muscle pain and sleep disturbances. Death occurs
because of degeneration of various organs of the body that can be seen
at autopsy.

Mercury is an industrial poison but previously it was used in the
treatment of syphilis, as a protection from rheumatism (quicksilver
was carried in the pocket) and as a diuretic.

The symptoms of acute poisoning are gastrointestinal, excess
salivation and renal failure. Chronic poisoning leads to black gums,
salivation, mandibular necrosis and encephalopathy. In the past when
felt for hats was made with the use of mercury the workers in this
industry could be distinguished by the characteristic "shake" and
personality changes.

Iron is best known for cases of acute poisoning in children who eat
ferrous sulphate (attractive-looking tablets prescribed for anaemia).
Gastrointestinal symptoms occur soon after ingestion, even 3-5 tablets
may be sufficient for death to occur. This happens due to the liver
damage and acidosis from release of free iron into the circulation,
because the trasferrin system that binds iron to protein is
overloaded.

NON-METALLIC IRRITANTS

Strychnine was first used in England around 1640 to poison dogs and
birds. The crystals are colourless but are of an extremely bitter
taste. This poison causes an excruciating agony, main effect being
muscle spasms and convulsions. The spasms are intermittent and easily
triggered by emotional or physical stimuli. The muscles can be torn
from their tendons and the victim feels the horrible pain, as there is
no loss of consciousness. Respiratory failure due to the spasm of the
intercostal muscles and the diaphragm leads to death. There are no
particular findings during an autopsy, apart from recovery of
strychnine from the body fluids and the stomach.

One of the famous cases of strychnine poisoning is the case of Dr.
Thomas Neill Cream in 1892. He came from America in 1891 and spent
last year of his life murdering prostitutes in the Lambeth area of
London. He gave his victims capsules with strychnine under the guise
that it would improve their complexions. Dr. Cream was arrested on the
charge of sending a threatening letter; paper with the dates of
murders and strychnine were found in his room during a search. He was
hanged on November the 15, 1892.

Organic phosphates were developed as insecticides in World War II.
They are also used as a basis of "nerve gases". They are extremely
toxic and block neuromuscular conduction by inhibiting cholinesterase.
The symptoms are nausea, vomiting, cramps and muscular twitching,
sweating and loss of appetite. Large doses will lead to a very rapid
death.

Cyanides are extremely poisonous. Thus died Sir Theodosius Boughton in
1780 from a poisonous draught given to him by his brother-in-law. This
relative would have benefited from the estate if he had not been
charged with murder and executed.

Potassium and sodium cyanides need to be mixed with water or gastric
acid before releasing free cyanide that acts as a cytochrome oxidase
inhibitor. Cyanides are used as a wasp killer and in some laboratory
techniques. Death is usually rapid but some victims have known to
survive.

At autopsy, the smell of cyanide - bitter almonds - may be obvious
(but ~ 40% of people can not smell it); the organs will be dark red
and congested. The oesophagus, in a case of swallowed cyanide, will be
black due to erosion and haemorrhage. The skin in the areas of
hypostasis will be of a purplish-pink colour due to
cyanmethaemoglobin.

**These of course are not all the poisonous substances known but a
brief description of some of the groups and their effects. Most
poisons do not leave specific traces and the picture present at
autopsy is of a general irritation of gastrointestinal tract,
pulmonary congestion or liver damage. Thus the detection of a
particular poison is left to a forensic toxicologist who has an array
of tests and techniques for toxicological analysis. These tests were
not mentioned here, as my task was a description of poisonous
substances and not the methods of their isolation.**

Literature used:

Knight B. Simpson's Forensic Medicine, 10th ed. London: Edward Arnold,
1991, pp. 265-312
Thompson CJS. Poisons and Poisoners With Historical accounts of Some
Famous Mysteries in Ancient and Modern Times. London: Harold Shaylor,
1931.
Trestrail JH. Criminal Poisoning Investigational Guide for Law
Enforcement, Toxicologists, Forensic scientists, and Attorneys. New
Jersey: Humana Press Inc, 2000, pp. 1-26, 105-17.
Knight B. Forensic Pathology, 2nd ed. London: Arnold, 1996, pp.
534-41.
Kampe S, Iffland R, Korenkov M, Diefenbach Ch. Survival from a lethal
blood concentration of cyanide with associated alcohol intoxication.
Anaesthesia 2000; 55: 1189-91.
Gordon I, Shapiro HA. Forensic Medicine A Guide to Principles, 2nd ed.
Edinburgh: Churchill Livingstone, 1982, pp. 192-217.
Curry AS. Poison Detection in Human Organs, 4th ed. Springfield:
Charles C Thomas, 1988.
Prozorovskyi VI. Sudebnaya Medicina. Moskva: Yuridicheskaya
Literatura, 1968, pp. 164-80 (Russian).
Pounder DJ, Jones GR. Post-mortem Drug Redistribution - a
Toxicological Nightmare. Forensic Sci Int 1990; 45: 253-63.
http://www.lts.mvm.ed.ac.uk/forensic - lectures on drugs and poisons
by Dr. B. Purdue.