If heavy metal poisoning is suspected e.g. arsenic or antimony, in addition to the usual samples, the following are also submitted: Bone (about 200 g); Hair usually from the head and/or pubis), plucked, not cut i.e. with roots intact (at least 10 g); Nails, preferably entire rather than clippings; Muscle; Skin, at least 2.5 square cm.
These samples are best kept refrigerated until submitted to the lab so as to retard putrefaction. If a sample of the suspected poison is available, this should also be sent to the lab for analysis.
Detailed descriptions of the autopsy findings in deaths from all common poisons are beyond the scope of these notes and can be found in basic texts on forensic pathology. A few common/classic cases will be mentioned as follows:
Examples are: (a) Ammonia (found in some cleaning fluids); (b) Caustic alkalis e.g. caustic soda (lye), caustic potash; (c) Sulphuric, hydrochloric or nitric acids; (d) Phenol (found in disinfectants e.g. Jeyes fluid, Lysol). In general, corrosives produce marked local tissue damage with acute inflammation and ulceration of the lips and upper G.I. tract (sometimes with perforation). Fumes from the volatile acids and ammonia can cause marked respiratory tract damage. Phenol causes characteristic white stains on the lips, a white swollen tongue and a striking gastritis. Corrosive poisoning is usually suicidal but may be accidental.
This is an odourless, colourless gas caused by the incomplete combustion (in a restricted supply of air) of carbon containing material (most fuels) e.g. using a paraffin stove in an unventilated room, running an automobile in a closed garage etc. Poisoning may be suicidal or accidental. The CO has a greater affinity for haemoglobin (over 200 times), than does oxygen, and forms carboxyhaemoglobin (HbCO). This preferentially binding leads to tissue hypoxia, despite the fact that the blood is rich in oxygen. HbCO has a characteristic bright cherry pink colour, which can be seen in the nail beds, lips, blood and viscera (). As a general rule, conversion of more than 50% of a person’s haemoglobin to HbCO will cause death.
Found in some photographic and industrial chemicals. In more recent times it has gained infamy by being implicated in criminal contamination of pharmaceuticals in the USA e.g.Tylenol and Sudafed, and was the poison of choice in the notorious Jim Jones affair in Jonesville, Guyana. Cyanide inhibits the cytochrome oxidase system and prevents oxygen uptake by the cells. The blood therefore remains fully oxygenated and is bright red (can be confused with CO poisoning). Death may be quite rapid and may occur within seconds! The classical false tooth that the spy bites down on to commit suicide in the novels and movies usually contains cyanide.
At autopsy, the organs are bright red and there is the characteristic smell of bitter almonds especially from the skull cavity and brain. However, many people - up to 80% of the population - have a congenital inability to detect the odour! If the victim lives a few days before dying, classical
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