Category: Toxicology

TOXICOLOGY is a branch of science that deals with the study of poison, their ori

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TOXICOLOGY is a branch of science that deals with the study of poison, their origin, physical and chemical properties, physiological action, treatment of their noxious effect, and methods of detection.
The word “toxicology” came from the Greek word for poison (toxicon) and scientific study (logos), and it was coined in the 16th century.
Forensic Toxicology
Forensic Toxicology is defined as the determination of drug use, poisoning, or exposure to toxic substances as part of a legal investigation.
Mathieu Orfila, a physician and chemist, is the “Father of Modern Toxicology”. He wrote the book “Traite Des Poisons”.
It was Dr. Alexander Gettler, a chemistry professor, who started the field of forensic chemistry and was considered the “Father of American Toxicology”.
Application of Forensic Toxicology
There are several applications of forensic toxicology, one of which is drug and alcohol testing. This is commonly performed in traffic accidents and in workplaces. Another use is for drug overdoses, whether these are intended or accidental. Forensic toxicology is also applied to sexual assault that involves the use of drugs. Through toxicology testing, a victim can find out that a drug was given and can be treated accordingly.
Forensic toxicology is also applied in cases of post-mortem investigations where toxicology is required to establish if an excessive intake of the drug occurred, and if so, whether this contributed to death.
Poison
Poison is a substance which when introduced in the body and is absorbed through the bloodstream and acts chemically and capable of producing noxious effects or even causes death.
Classification of Poisons
1. According to Origin
a.Vegetable poison or plant poisons – poisons from plants (e.g. castor bean)
b.Animal poisons/toxins – poisons transferred through bites and stings of marine animals or terrestrial animals(e.g. snake bites, sting from bees)
c.Mineral poisons – strong acid and strong base (e.g. hydrochloric acid)
d.Microbial poisons – poisons produced by microscopic organism (e.g. bacteria and fungi)
e.Synthetic poisons – poisons that are chemically produced in the laboratory that have useful importance to its purpose but become poisonous when taken into the body (e.g. household cleaners, drug overdose)
2. According to Chemical Properties
a.Volatile poisons – poisons that are unstable and easily affected by heat.(e.g. halogen compounds, alcohols)
b.Non-volatile poisons – poisons that are stable. Most poisons are non-volatile in nature. (e.g. tobacco, organic acids)
c.Organic poisons – poisons that include glucosides, animal poisons, bacterial poison, alkaloids.
Alkaloids are nitrogenous organic basic compound with bitter taste containing
usually oxygen that occurs especially in seeds of plants.
d.Inorganic poisons – poisons that include volatile as well as non-volatile, mineral acids and mineral alkalis.
3. According to Physiological Action
a.Corrosives – are highly irritant poisons that cause local destruction of tissues and are characterized by nausea, vomiting, and great local distress. (e.g. strong acids and alkalis)
b.Irritants – are poisons that produce irritation and inflammation of the mucus membrane and are characterized by vomiting, pain in the abdomen, and purging. (e.g. arsenic)
c.Narcotics – poisons that produce stupor, complete insensibility, loss of feeling. (e.g. cocaine, methamphetamine hydrochloride, ecstasy)
d.Neurotics – poisons that act chiefly on the nervous system producing delirium, convulsion, and respiration as the outstanding symptoms. (e.g. alcohol, carbon monoxide, opium)
e.Tetanics – poisons that act directly upon the spinal producing such spasmodic and continuous contraction of muscles as a result of stiffness. (e.g. bacteria found in soil, manure and contaminated drinking water)
f.Depressants or sedatives – agents that retard or depress the physiological action of the organ or slow down the functioning of the brain. (e.g. nicotine, cocaine)
4. According to Physical Form or State
a.Solid
b.Liquid
c.Gas
d.Vapor
e.Aerosol
Types of Poisoning
There are two types of poisoning and these are: according to the medical point of view and according to the legal point of view.
1. According to the medical point of view
(a)Acute poisoning – one in which there is prompt and marked disturbance or death within a short period of time due to either taking a strong poison in an excessive single dose or several doses at short intervals.
(b)Chronic poisoning – one in which there is gradual deterioration of functions of tissues and may or may not result in death. It is produced by taking several small doses at long intervals taking the toxic doses of the drug.
2. According to the legal point of view
(a)Accidental poisoning – is one in which the poison was taken without intention to cause death or may be taken by mistake or without knowing that the substance taken was poisonous.
(b)Suicidal poisoning – is one in which the poison was taken by the victim voluntarily for the purpose of taking his own life.
(c)Homicidal poisoning – is one in which the poison was given willfully and with intent to cause the death of the victim.
(d)Undetermined – is one in which the history is hazy as to how the poison was obtained and why it was administered.
Conditions Modifying the Action of Poisons
There are two conditions modifying the action of poisons and these are: conditions attributed to the individual and conditions attributed to the poison.
1. Those attributed to the individual:
(a)Age and sex
(b)Health
(c)Diseases
(d)Food
(e)Exhaustion
(f)Habit – is the repeated taking of small doses of the drug.
(g)Idiosyncrasy – is a term applied to individuals who exhibit unusual behavior to certain substances.
2. Those attributed to the poison
(a)Physical state or form of the poison – A poison is more rapidly absorbed when it is in the gaseous state.
(b)Dilution – Diluted poison is rapidly absorbed than concentrated ones, except in cases of corrosive poisons.
(c)Solubility of the poison – The effect of poison is dependent whether it is soluble or not. For example, barium chloride is readily soluble, and is extremely toxic while barium sulfate is not because it is insoluble.
(d) Mode of administration at one time – Intravenous injection has the most rapid effect.
(e) Dose – the quantity of a substance to be administered at one time.
Kinds of Dose
1.Safe dose – one that does not cause any harmful effect.
2.Toxic or poisonous dose – one that is harmful to both healthy and sick.
3.Lethal dose – one that kills.
4.Minimum dose – is the smallest amount that will produce the therapeutic effect without causing harm.
5.Maximum dose – is the largest amount that will cause no harm and at the same time produce the desired therapeutic effect.
Posology – is a branch of medical science which deals with the dose or quantity of drugs which can be administered to a patient to get the desired pharmacological action.
Pharmacology – the branch of medicine concerned with the uses, effects, and modes of action of drugs.
Entrance and Elimination of Poison
Poisons can enter the body through: the mouth and are absorbed through the stomach and intestinal wall, through the nose and enter the blood from the upper respiratory passages or lungs, skin, eyes, vagina, through hypodermic and intravenous injection.
Poisons can be eliminated through emesis, respiration, urine, feces, milk, saliva, sweat and tears. Meanwhile, the elimination of poisons can be also done with the administration of antidotes.
Antidotes are substances used to counteract or neutralize the effect of poisons.
Kinds of Antidotes
1.Mechanical antidote or Physical antidote – is an agent that removes the poison without changing it. Examples are stomach pumps and ligatures, emetics, cathartics, precipitants. Emetics are substances that induce vomiting.
Cathartics – are agents that produce intestinal evacuation.
Precipitants – are substances that prevent absorption of poison by precipitating them and rendering them insoluble.
2.Chemical antidote – is a substance that makes the poison harmless by chemically altering it. An example is caffeine given to morphine overdose.
3.Physiological antidote – sometimes known as antagonist. It is an agent that acts upon the system so as to counteract the effect of the poison. Examples are atropine and physostigmine.
4.Universal antidote – is a combination of chemical and physical antidotes and usually given to persons suspected to have taken two or more poisons. Example is a mixture of powdered charcoal, tannic acid and magnesium oxide.
General Treatment of Poisoning
After the physician has recognized that he is dealing with a poisoning case, his chief effort should be directed towards the following:
1.Removal of the poison from the stomach
If the poison was taken orally, the removal of poison is brought about by inducing vomiting by emetics and use of stomach pumps; if the poison was injected, use ligatures and bleeding; if poison was applied, remove by washing.
2.Administration of antidotes
Antidote is given to the patient to counteract or neutralize the effect of the poison.
3.Elimination of the poison by excretion
Poisons are eliminated through the excretory organs. This is done by intravenous infusion of saline solution, diluted alkali solution, or diluted solution of glucose. The poison is generally excreted through the urine, feces, vomitus or saliva.
4.Stimulation and other symptomatic effect
If the patient is suffering from excessive pain, morphine is given; for convulsion, chloroform; and for shock, oxygen inhalation.
5.Special treatment
If the poison is in the form of gas, there is an immediate need of fresh air or artificial respiration. If poison is external like burn from concentrated acid, wash with plenty of water or alcohol or lime water. If it is caused by alkali burn, wash with lemon or other citrus fruits. If the poison came from a bite or injection, the poison can be checked by applying a tourniquet or restricting the band tightly above the wound. This retards the absorption of the poison by the blood.
Methods of Examination of Poison
Methods of examination of poison are divided into two stages namely: isolation and identification.
1.Isolation
Isolation is the process of isolating and reducing the poison into its pure form through distillation with or without current of steam, solvent extraction and chromatographic examinations.
2.Identification
Identification is done to identify the poisons by screening and performing the different tests. The tests are: preliminary tests that include flame test and microscopic examination. Then confirmatory test to establish the presence of poisons, and modern instrumental methods such as Gas Chromatography test.
Specimens/Organs to be Submitted for Chemico-Toxicological Analysis
1.Stomach contents – all available in case of poisoning taken by mouth within a few hours.
2.Stomach – the whole stomach for all types of poisoning taken by mouth.
3.Intestinal contents – all available for cases in which poison was taken by mouth within one or two days.
4.Liver (300 grams) – for metals, barbiturates, fluorides, oxalate and other poisons
5.Kidney – one kidney for Hg poisoning.
6.Blood – at least 10 cc for all gas poisons, alcoholism, drowning for chloride contents.
7.Brain(500 grams) – for volatile poisons, barbiturates, alcoholism, alkaloids.
8.Urine – all available in nearly all types of poisoning.
9.Muscles(200 grams) – most acute poisoning and internal organs that are badly putrefied.
10.Bone(200 grams) – for lead, arsenic and radium poisoning.
11.Hair(5grams) for chronic arsenic poisoning.
Common Volatile, Non-Volatile, and Metallic Poisons
Benzene – also called benzol, a solvent for rubber, gums, resins and fats.
Carbon Disulfide – a solvent for sulfur.
Nitrobenzene – a pale yellow, oily liquid with a sweet odor resembling oil of bitter almond.
Acetone – used as solvent for cellulose acetate and nitrocellulose.
Ether – used as a general anesthesia, a highly volatile and inflammable liquid.
Caffeine – substance found in coffee.
Salicylic acid – found in “ap-ap” solution.
Formalin – an embalming fluid.
Cocaine – drug found in coca leaf.
Picrotoxin – derived from fish berries, locally known as lagtang.
Ethyl alcohol or ethanol – alcohol found in wine, also called grain alcohol.
Barbiturates – sleeping pills.
Strychnine – an alkaloid found in dried ripe fruits of nux vomica.
Nicotine – found in tobacco leaves.
Morphine – found in poppy plants, an alkaloid present in opium by about 9%.
Physostigmine – also called serine, found in calabar beans.
Chloral hydrate – used as knock out drops.
Carbolic acid or phenol – obtained from coal tar, a very violent poison.
Arsenic – used as a rat poison.
Lysol – used as a disinfectant.
Methyl alcohol – causes blindness, also called wood alcohol.
Chloroform – colorless liquid with a sweet taste used as an anesthesia.
Carbon tetrachloride – used as a dry cleaning agent, found in “pyrene” fire extinguisher.
Formic acid – acid found in ants and spiders.
Hydrogen cyanide – poison found in kamoteng kahoy, also called hydrocyanic acid or prussic acid.
Acetic acid – acid found in vinegar, in pure form it is called glacial acetic acid.
Aspirin – used as an analgesic.
Amygdalin – poison found in bitter almonds.
Phosphorous – a volatile poison that glows in the dark.
Ptomaine – poison found in dead or decaying matter or spoiled meat.
Isopropyl alcohol – found in rubbing alcohol, also called propyl alcohol.
Cannabinoids – poison found in marijuana and hashish.
Methamphetamine hydrochloride – a dangerous drug commonly known as shabu.
Potassium cyanide – it is called a jeweler’s solution.
Codeine – substance found in cough syrup, also known as methyl morphine.
Cantharide – used as an aphrodisiac.
Carbon monoxide – produced by the incomplete combustion of carbon, found in exhaust of automobiles.
Bufotoxin, bufotalin – poisonous substance isolated from the skin of poisonous frogs.
Toluene – colorless, mobile, inflammable liquid found in “rugby”.
Methylenedioxymethamphetamine(MDMA) – commonly known as “ecstasy”.