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lethal intoxication (Group tests (Group 1 poisons: gases (Symptoms: Apnoea…
lethal intoxication
Group tests
Group 1 poisons: gases
- Symptoms: Apnoea, asphyxia, dyspnoea, vomiting; pink or red skin colour, The classic pink skin colour from carboxyhaemoglobin is not always apparent
- Occupation: Chemical industry, electroplating, fumigation, furnaces, glue factories, industrial tank cleaning, jewellery, metal treatment, mines, photography, sewers, tanneries
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Group 4 poisons: metals
- Symptoms: Anaemia, cramps, diarrhoea, gastric pain, hair loss (thallium and selenium), jaundice, metallic taste, paralysis, peripheral neuritis, salivation, urine retention, vomiting, weight loss
- Onset: after several hours; death may occur within 24 h, but more commonly after days (with acute rather than chronic poisoning)
- Occupation: Electroplating, smelting; manufacture of agricultural chemicals, alloys, batteries, ceramics, glass, paint, petroleum products
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Group 6 poisons: anions
- Poisoning from this group of poisons is fairly rare
- Symptoms: Violent vomiting, diarrhoea, abdominal pain, cyanosis (methaemoglobin), stained skin and mucosa (permanganate, oxalate, iodide and bleaching agents)
- Onset: within 1 h, death may occur within several hours (toxic dose of this group is large, >10 g)
Analytical probing
- Medicaments and other materials near the body
- Food or drink near the body
- Body fluids (at least 10-50 ml/g):
urine (screening tests)
stomach contents (examined visually for colour and the presence of tablet residues)
- blood (visual examination of the blood may immediately
indicate carbon monoxide poisoning → bright cherry–red specimen and brown blood as a result of methaemoglobinaemia may
→ signify poisoning by oxidising agents such as chlorate)
- Liver should still be requested as a routine specimen in every postmortem case
- Tissue analysis is a necessity for exhumed or decomposed bodies, or when the victim has survived for several days after ingestion of the poison
principles
• All chemists must have toxicological experience.
• The analyst must be given a complete case history that contains all the information available.
• All the evidential material ,suitably labelled and sealed in clean containers, must be submitted and examined.
• All the known identification tests should be applied and adequate notes made at the time.
• All the necessary reagents used for these tests should be pure, and blank tests should be performed to establish this fact.
• All tests should be repeated ,and compared with control samples to which the indicated poison has been added.
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General guidance
- If the time of onset of the symptoms was less than 1 h, and there is no evidence of injected material, the sample should be examined for gases and volatile poisons before other groups.
- Severe vomiting and diarrhoea indicate possible metal poisoning
- The age and occupation of the victim: Teenagers indulge in solvent abuse, farm workers by toxic pesticides and a death in an electroplating factory requires cyanide to be eliminated.
- Poison – substance that causes intoxication, which causes a disturbance in the function or death.
- Forensic toxicology is the application of the science and study of poisons to provide answers to questions that may arise during criminal investigations or judicial proceedings.
- Toxin – natural strong poison produced by animals (zootoxin) or plants (phytotoxin)
- LD-50, a dose at which 50% of subjects will die.
- Haber's Law for for toxic substances in the air.
The lethal effect (E0) is achieved as the product of the concentration (C) and exposure time (t).
- Factors influencing toxicity:
the dosage (most important factors of toxicity), pathway of administration,
time of exposure, age, sex,
nr. of exposure, physical form of toxin,
individual genetics, overall health
- Major groups of poisons:
Miscellaneous substances e.g. dioxins (GC, LC-MS),
Gases e.g.CO, CN
Naturals toxins e.g. amanitin (mushrooms)
Anions e.g. nitrates, phosphides
drugs, metals, volatile substances, pesticides
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