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Forensic toxicology Flashcards

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1
Q

Acute poisining

A

− Accidental / Suicidal / Homicidal

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2
Q

Chronic
poisoning

A

− Pollution
− Industrial
− Intentiona

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3
Q

Toxicity

A

state of being
poisonous…effect of a poison on
a cell

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4
Q

lethal dose

A

represents the
dose of a particular drug at
which all subjects will die if they
have taken the drug (g,mg,kg)

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5
Q

LD50

A
  • dose at which 50% of those
    who have taken a particular dose of a
    substance will die
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6
Q

Poison

A

any substance, either
taken internally or applied
externally, that is injurious to
health or dangerous to life
(Stedman’s)

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7
Q

Weitermachen’s definition of drug tolerance

A

Increased doses of a drug
produce less and less effect

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8
Q

Weitermachen’s definition of substance dependence

A

Unanticipated drug reactions

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9
Q

Weitermachen’s definition of drug indiosyncrasies

A

Impaired functioning of an
individual in the absence of a
specific drug

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10
Q

Weitermachen’s definition of drug interaction

A

Unanticipated effects resulting
after 2 or more different drugs
are taken/given

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11
Q

Three way of classifying poisons

A

a) According to their effects on the body as a whole and specific
organs
b) According to their chemical composition and method of
administration
c) According to their application or use

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12
Q

classification schema

A
  1. agricultural poisoning
  2. industrial poisons
  3. household poisons
  4. poisonous plants
  5. animals and insects
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13
Q

Agricultural poisons

A
  • Insecticides
  • (DDT,organophosphates) Herbicides (paraquat)
  • Rodenticides (thallium)
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14
Q

Industrial poisons

A

– Gases (carbon monoxide,
cyanide)
– Heavy metals (lead, mecury,
arsenic)
– Hydrocarbons (paraffin, benzene)
– Caustic substances (acids, alkalis)

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15
Q

Household poisons

A

-Medicines (eg. Insulin)
– Insecticides
– Detergents

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16
Q

poisonous plants

A

mushrooms

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17
Q

Animals and insects

A

Animals and insects– Snakes, spiders, scorpions, bees
(technically venomous

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18
Q

Factors influencing toxicity

A

Dose-response relationship
Biological factors
Chemical factors

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19
Q

Dose-response relationship

A

–LD50
– Cumulative frequency distribution
– Standard deviatio

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20
Q

Biological factors

A

–Absorption (diffusion or active transport)
–Accumulation / storage
– Distribution
– Elimination
– Functional reserve of organ
– Tolerance

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21
Q

Chemical factors

A

– Effect on specific receptor or cell (eg. CO)–
Biotransformation

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22
Q

What is the route of administration according to Weitermachen?

A

-Skin
– Lungs
– Gastrointestinal
– Parenteral

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23
Q

What are the genetic factors acc to Weitermachen?

A

– Congenital absence or abnormality of an enzyme (eg. malignant
hyperthermia with Scoline– ryanodine -re abnormality)
– Rate of metabolism of drugs (eg. INH)
– Abnormal reactions (eg. porphyria

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24
Q

What are some additional concerns in drug administration? (miscellaneous factors)

A

Anaphylaxis – A life-threatening allergic reaction requiring immediate intervention.

Cytotoxic drugs – Used in chemotherapy, these drugs target rapidly dividing cells and require careful handling.

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25
How is the diagnosis made?
1. History 2. Symptoms 3. Signs 4. Pathological proof − Organ and tissue examination − Body fluids examination − Ancillary examinations
26
What is a key characteristic of autopsy findings?
Autopsy results are often non-specific, meaning additional testing is required for definitive conclusions.
27
What is clinical-pathological correlation?
It is the process of comparing clinical symptoms and medical history with autopsy findings to identify causes of death.
28
What role does histology play in post-mortem examinations?
Histology involves examining tissue samples under a microscope to detect diseases, cellular abnormalities, and injury patterns.
29
What factors are analyzed in a toxicology examination?
Presence of compounds – Detecting substances in the body. Levels of compounds – Measuring substance concentration. Range of compounds – Determining whether levels fall within normal or toxic ranges.
30
Specific poisinings
* Carbon monoxide * Cyanide * Heavy metals * Corrosive poisons * Organophosphate * Organic solvents
31
Most common cause of poisoning apart from alchohol and medicinal drugs
Carbon monoxide
32
Circumsances in which carbon monoxide occurs
– petrol engines (suicides) – faulty gas appliances and heating systems – fires in confined spaces – industrial - steel work
33
Define carbon monoxide
Incomplete combustion of fossil fuels in an inadequate oxygen supply environment
34
How does CO poisoning cause death?
In confined spaces (e.g., inside a vehicle), CO displaces oxygen, leading to hypoxic hypoxia. CO has a 300 times greater affinity for hemoglobin than oxygen, displacing oxygen from red blood cells (anemic hypoxia). Tissues lose the ability to utilize available oxygen, causing histotoxic hypoxia.
35
What are visible signs of CO poisoning during an autopsy?
Cherry-pink coloration of the skin, particularly hypostatic areas and internal tissues. Bilateral necrosis of the basal ganglia in cases where the acute episode was survived.(The deep part of the brain that helps control movement was damaged on both sides, but the person survived the health crisis.)
36
How is CO poisoning confirmed toxicologically?
Gas chromatographic analysis of blood or tissue is used. Carboxyhemoglobin saturation above 50–60% is typically fatal.
37
How does cyanide salt become toxic?
When swallowed, it must encounter water or gastric acid, which liberates hydrogen cyanide (HCN) gas or cyanide acid.
38
What is the fatal dose of cyanide salt?
150–300 mg is considered lethal.
39
In what circumstances do cyanide-related fatalities occur?
* Accidental exposure during fumigation * Laboratory accidents * Suicidal cases, often involving laboratory staff or religious sects * Inhalation of toxic gases during fires
40
How does cyanide cause death?
Prevents oxygen uptake by cells by inhibiting cytochrome oxidase, leading to histotoxic hypoxia. Local erosive damage may occur in the gastrointestinal tract.
41
What are the main autopsy signs of cyanide poisoning?
* Brick-red/purplish-pink skin coloration, particularly in hypostatic areas. * Characteristic bitter almond smell. * Deep red or black erosion of the oesophagus and stomach lining due to hemorrhage.
42
How do heavy metals affect the body?
They bind to mitochondrial enzymes, disrupting metabolic processes. They interfere with cellular respiration, leading to systemic toxicity. They target vascular endothelial cells, causing widespread damage. They can affect the gastrointestinal tract (GIT), leading to severe symptoms.
43
How does arsenic affect the body?
Arsenic is highly toxic, with both acute and chronic effects:
44
Examples of acute poisoning effects
Haemorrhagic gastritis (severe stomach lining inflammation) Subendocardial haemorrhage (bleeding under the inner heart lining) Tubular necrosis (kidney damage)
45
Examples of chronic poisoning effects
Hyperkeratosis (thickened skin) Skin thickening Hair loss
46
What are common corrosive substances?
Acids – Dehydrate tissue, coagulate protein, change hemoglobin (Hb) into haematin. Alkalis – Cause severe burns and tissue damage. Miscellaneous substances – Includes heavy metal salts and detergents, which have toxic effects
47
What are post-mortem findings in corrosive poisoning cases
* Skin erosion, reflecting the deceased’s posture during intake. * Diffuse erosion of upper gastrointestinal mucosa, sometimes leading to perforation and chemical peritonitis. * Aspiration, which may result in chemical pneumonitis. * Complications, such as scarring with stenosis.
48
What is lye and how does it affect the body?
Lye (caustic soda) is a strong alkali metal hydroxide, mainly NaOH or KOH. Used in soap-making, but can digest tissue when ingested or contacted.
49
What dosage of elemental iron is toxic?
20–60 mg/kg can cause iron poisoning. Over 120 mg/kg is typically fatal.
50
What is parathion and how does poisoning occur?
* Parathion is an agrochemical poison (pesticide/insecticide). * It can be absorbed through the skin, ingested orally, or inhaled. * It inhibits choline esterase (CE) enzymes, disrupting nerve function.
51
When do toxic effects of a a parathion begin?
Toxicity occurs when CE levels drop below 30%.
52
What symptoms occur with parathion poisoning?
Large doses: Death occurs rapidly. Smaller doses: Symptoms include nausea, vomiting, blurred vision, contracted pupils, hypersalivation, increased bronchial secretions, twitching, and convulsions, followed by death.
53
What are post-mortem findings in parathion poisoning?
Findings are non-specific, but toxicology may confirm poisoning by: * Detecting organophosphates in body fluids. * Measuring CE levels in blood.
54
What is strychnine?
A highly toxic pesticide. Acts as a neurotoxin, antagonizing glycine and acetylcholine.
55
How does strychnine poisoning affect the body?
It primarily targets motor nerve fibers in the spinal cord, leading to muscle contractions. Causes asphyxia-type death due to severe muscle rigidity.
56
What is the minimum lethal oral dose of strychnine in adults?
30–120 mg.
57
What determines a substance’s ability to dissolve another?
Compatibility of molecular structures—substances with similar molecular characteristics dissolve each other ("like dissolves like").
58
List the different types of solvents
Polar protic solvents Dipolar aprotic solvents Non-polar solvents
59
Polar protic solvents
Consist of a polar OH group and a non-polar tail. Formula: R-OH. Miscible with water (hydrophilic) and dissolve other polar protic substances.
60
examples of polar protic solvents
Water acetic acid methanol ethanol, n-propanol, n-butanol.
61
Dipolar aprotic solvents
Have a large bond dipole moment but lack an OH group.
62
Examples of dipolar aprotic solvents
Acetone ethyl acetate, dimethyl sulfoxide acetonitrile dimethylformamide.
63
Non-Polar Solvents
Evenly distributed electric charge, low dielectric constant. Hydrophobic (immiscible with water) but lipophilic, dissolving non-polar substances (oils, fats, greases).
64
examples of non-polar aprotic solvents
Carbon tetrachloride, benzene, diethyl ether, hexane, methylene chloride.
65
What defines an organic solvent?
A liquid that dissolves substances without causing chemical changes.
66
Types of organic solvents
Oxygenated (alcohols, glycol ethers). Hydrocarbonated (aliphatic, white spirits, pure aromatics). Halogenated (chlorine, bromine, iodine).
67
examples of organic solvents
Benzene, toluene, petrol, butane.
68
What are the dangers of organic solvents
: "Glue-sniffing" (e.g., toluene-based adhesive) can cause sudden cardiac death. Sensitization of the myocardium to catecholamines → sudden arrhythmias and death. Hypoxic hypoxia (if inhaled from a plastic bag over the nose/mouth). Cold air stimulation of hypopharyngeal neural networks, causing reflex cardiac arrest. Damage to the liver, kidneys, and bone marrow.
69
what are inorganic solvents
Solvents without carbon, often aqueous solutions with additives.
70
examples of inorganic solvents
Water (H₂O). Liquid anhydrous ammonia. Concentrated sulfuric acid. Sulfuryl chloride fluoride.
71
What is Digoxin?
Digoxin is a cardiac drug derived from Digitalis purpurea, used to treat heart conditions such as atrial fibrillation and heart failure
72
What is Insulin?
Insulin is a peptide hormone produced by beta cells of the pancreatic islets. It regulates blood glucose levels in the body.
73
What is copper sulphate used for?
It is a pesticide effective against algae, bacteria, and fungi.
74
How much copper sulphate ingestion causes toxicity?
Ingesting more than 1g can result in severe toxic symptoms.
75
What are the clinical manifestations of copper sulphate poisoning?
* Erosive gastropathy (severe stomach lining damage). * Intravascular haemolysis (destruction of red blood cells). * Methaemoglobinaemia (altered hemoglobin function reducing oxygen transport). * Hepatitis (liver inflammation). * Acute kidney injury (kidney failure risk). * Rhabdomyolysis (muscle breakdown). * Arrhythmias and seizures.

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