1. Toxicology- Toxicology is derived from a Greek word which means “an arrow”. Toxicology is the study of substance which has toxic properties in human body. It also studies the harmful effects on the body. It basically gives out about a poison, its properties, sources and mode of action, lethal dose, and many more.
2. Forensic toxicology- Forensic toxicology is the study which is concerned with the medico-legal aspects of the poisons which produces harmful effects on human or animal.
3. Poison- Anything, maybe solid, liquid or gas, introduced in living body, that is, through inhalation, ingestion or injection (intravenous, cutaneous, intraocular, etc.) which produces ill health, disease or death is called poison.
4. Drug- A chemical which is given to cure ill health, death or save the life of the patient is known as drug.
*Dose- Dose is any fixed amount of drug. The dose is fixed after the clinical trials are conducted in labs.
*Therapeutic Drug- After checking the health of the patient, the required dose for the treatment of the disease is given to the patient. This is known as therapeutic drug.
5. Fatal Dose- Fatal dose is the fixed amount of any drug which shows adverse effects on the body after ingestion.
6. Fatal Period- Fatal period is the time at which the harmful effects of the drugs after ingestion starts to showcase in a human body.
7. Lethal dose 50/ LD 50- Lethal dose 50/ LD 50 is the amount of a chemical/material, given all at once and thus causes the death of 50% (one-and-half) of a group of animals being tested during the observation period. It can be a method to measure the acute toxicity of a chemical substance/material.
8. Lethal concentration 50/ LC 50- Lethal concentration 50/ LC 50 is the concentration of a chemical present in air that causes the death of 50% of the test animals during the observation period.
9. Toxinology- It is the study of science which deals with the harmful effects produced by toxins. Toxins are produced by plants, animals, bacteria and fungi which have proven to be harmful to human being.
Classification of poisons
1. According to their mode of action or chief symptoms.
2. On the basis of chemical analysis.
3. Medico-legal classification
I. According to their mode of action or chief symptoms
Corrosives
Ø Principle- Corrosives corrode the human tissues.
Ø The tissues are destroyed by direct chemical action (Strong mineral acids & their carbonates, alkalis, etc.) on the living tissue.
Ø They are highly active irritants which causes discomfort to the body.
Ø Ulceration or breaking on skin or on surface of the affected organ of the tissue is also observed.
Ø They produce local action on the affected organ.
Ø Mineral acids- H2SO4, HNO3, HCl, etc.
Ø Organic Acids- oxalic acid, lactic acid, uric acid, etc.
Ø Conc. Alkalis- caustic soda, caustic potash, carbonates of ammonium, sodium and potassium.
Irritants
Ø Principle- Irritants causes irritation and inflammation by their specific action in the affected organs of the human body.
Ø They enter into the body through thin layers of the body.
Ø Examples- Irritation through dust and pollen.
Ø They produce symptoms of pain, vomiting and purging.
Ø They show redness or ulceration of the GIT (gastro-intestinal tract) in the postmortem appearances.
Ø Inorganic-
1. Metallic- Arsenic, antimony, mercury, thallium, zinc, etc.
2. Non- metallic- Phosphorus, Chlorine, Bromine, Iodine.
Ø Organic-
1. Vegetable- seeds, roots, fruits.
2. Animal- cantharides, snakes, spiders, insects, etc.
Ø Mechanical-
Coarsely powdered glass, chopped hair, dried sponge, diamond dust.
Neurotics
Ø Neurotics show systemic action in the body and specific action on nervous system.
Ø They also act on heart and can produce injurious effects like delirium, tremors, convulsions, and coma.
Ø They are local irritant poison.
Ø All the alkaloid poisons fall under this group.
Ø They show symptoms of headache, giddiness, stupor, drowsiness, delirium, paralysis, etc.
Ø Cerebral- Acts on brain & cause death by coma, sudden memory loss. It can cause Ataxia, paralysis, necrosis, etc.
Ø Spinal- Acts on spinal cord. Ex- Nux vomica & its alkaloids, gelsemium, physostigmine, etc.
Ø Cardiac- Acts on the heart. Ex- Digitalis, oleander, aconite, etc.
Ø Asphyxiants- Acts on lungs. They get dissolved in blood (CO2, CO, coal gas, sewer gas), irrespirable drugs.
Ø Peripheral- Acts on peripheral nerve endings. Ex- Curare, conium, etc.
II. On the basis of chemical analysis
1. Noxious gases-It causes harm to society or public.
Ex- CO, CO2, H2S, SO2, Cl2, N2O, CH4, CH3NCO, war gases, ammonia, tear gas (chloracetophenol)
2. Volatile Inorganic- Cyanide, stilbine, phosphine, carbonyl chloride, arsine, fluorocarbon, phosgene, isocyanides.
3. Volatile organic- Methanol, ethanol, chloral hydrate, pyridine, formaldehyde, acetaldehyde, ketones, chloroform, hydrocarbons, etc.
4. Non- volatile Inorganic-
Anions- Halides, selenide, dichromate, chlorate, nitrite, sulphate, phosphide, etc.
Cations- Mercury, arsenic, barium, thallium, lead, antimony, bismuth, copper, aluminum, zinc, etc.
5. Non- volatile organic neutral compounds- Pesticides, (Organo-phosphorus, Organo chloro, carbamates and pyrethroids) neutral compounds.
6. Non- volatile organic acidic compounds- Barbiturates, sulpha & phenolic compounds, salicylates, etc.
7. Non- volatile organic alkaline compounds- All basic drugs like benzodiazepines, alkaloids, etc.
8. Plant poisons- Dhatura, aconite, oleander, Nux vomica, Abrus precatorius, etc.
9. Miscellaneous poisons-
a) Mechanical- Glass powder, diamond dust, chopped hair, etc.
b) Food poisons/ myco-toxins
c) Animal/ insect poisons
d) Water soluble compounds
III. Medico-legal classification
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