Forensic Toxicology-1.pptx

It is very simple slides for forensic medicine

1. DR . Asmat " Danish" Class: 6-S1

2. History of Toxicology Father of toxicology is Swiss physician Paracelsus, he was a 16 th century physician “all substances are poisons, there is none which is not a poison. The right dose differentiates a poison from remedy” The study and classification of toxic substances was first systemized by Matthieu Orfila (1787-1853). Spanish chemist and physician wrote the book which name was “ Traite des poisons” in 1814 (modern father of toxicology) Socrates, a Greek philosopher, is example of a historical figure poisoned to death by hemlock around 399 BC. The active chemical that killed Socrates is alkaloid coniine, which when ingested causes paralysis, convulsion and death Cleopatra was commited sucide in 30 B.C., by allowing a poisonous snake to bite her.

3. Definition of Toxicology The word toxicology comes from the Greek word for poison( toxicon ) and scientific study (logos) The branch of science concerned with the nature, effects, and detection of poisons and the treatment of poisoning Toxicology is the science which deals with poisons with reference to their sources, properties, mode of action, symptoms which they produce, lethal dose, nature of fatal results, treatment, methods of their detection and estimation, and autopsy findings.

4. Branches of Toxicology Clinical toxicology Medical toxicology Forensic toxicology Industrial toxicology Environmental toxicology Biochemical and molecular toxicology Developmental toxicology

5. Forensic Toxicology Forensic toxicology deals with the medical and legal aspects of the harmful effects of poisonous substances on the human body Clinical toxicology deals with diagnosis and treatment of human poisoning Toxinology : is the science which deals with toxins produced by plants, animals, bacteria and fungi, which are harmful to human

6. Poisons Poisons are substances which are deleterious or injurious to the body leading to deformity, death or illness. Poison is a substance(solid, liquid or gas), which if introduced in the living body, or brought into contact with any part thereof, will produce ill health or death

7. Medico legal aspect of poisoning In all the cases of poisoning whether suicidal or homicidal, it is the duty of the attending physician to disclose to the police whatsoever information is available. Suppression of the information or providing wrong information makes the doctor legally responsible under section 202 and 193 of IPC( I ndian penal code) Sections 284, 299, 300, 304A, 324, 326 and 328 IPC deals with offenses relating to administration of poisons.

8. Classification of poisons (according to mode of action) Corrosives : strong acids and strong alkalis(mineral acid, organic acids, vegetable acids and concentrated alkalis) Irritants : corrosives in dilute solution act as irritant(organic, inorganics, mechanical) Neurotics : act on the nervous system(cerebral, spinal and peripheral) Cardiac : act on the heart (Digitalis, nicotine) Asphyxiants : act on the lungs(CO, CO2, War gases) Miscellaneous : antipyretics, analgesics, antihistaminic, antidepressant, stimulants

9. Routes of administration of poisons Enteral: mouth, rectum, enteral mucous membrane, sublingual Parenteral: IM, IV, intradermal, subcutaneous, intra arterial, intra peritoneal, intrathecal , bone marrow, intra cardiac Inhalation: through the air passage External application: wounds, unbroken skin Introduction into natural orifices: rectum, vagina, urethra, nose, eye

10. Action of poisons Local : direct action on the part and may cause corrosion as in the case of strong mineral acids; or congestion and inflammation as in the case of irritants Remote : is due to absorption of the poison into the system, it may be either specific or non specific Local and remote : oxalic acid, carbolic acid General : when the absorbed poison evokes response from a wide variety of tissue e.g. arsenic, mercury, lead, barbiturates etc

11. Factors which modify the action of poisons Dose: small doses produce therapeutic action; large doses produce toxic effect Form of poison: physical state, chemical combination and mechanical combination Method of administration: inhaled- IV- IM- subcutaneously- swallowed Condition of the body: age, state of health, sleep and intoxication

12. Toxicokinetics The term is most commonly used when describing the time course of absorption, distribution,metabolism and elimination (including biotransformation and excretion) of toxicants in an organism.

13. Toxicodynamics Describes the mechanism or mode of action of toxicants, how they can cause tissue damage, and under what conditions in term of tissue concentrations and time of tissue exposure/ dose do adverse effects on tissue structure and function occur

14. Difference between toxicokinetics and toxicodynamics Toxikonetics describes how a toxicant( poison) enters the body and reaches a target tissue and elimination. Toxicodynamics describes what happens to that tissue once the toxicant reaches an effective dose.

15. Poisoning in the living The evidence of poisoning depends upon whether the poisoning is acute or chronic Acute poisoning: symptoms suddenly appear soon after the suspected food, medicine or fluid has been taken, although in bacterial food poisoning, the symptoms may be delayed. The symptoms rapidly increase in severity and are followed by death or recovery. Poison can be detected in the ingested food, medicine, and fluid, or vomit, gastric lavage, blood, urine and stool of the victim.

16. Continues… poisoning in the living Chronic poisoning: symptoms develop insidiously and gradually. Poison can be detected in the food, medicine or fluid which is being administered or in the vomit, urine or stool of the victim. While the main symptoms in chronic poisoning are usually malaise, and gradual deterioration of health, repeated attacks of undiagnosed gastrointestinal irritation should arouse suspicion of homicidal poisoning.

17. Poison in the dead The evidence of poisoning will depend on: Postmortem examination Chemical analysis Experiments on suitable animals Moral and circumstantial evidence In a number of cases, therefore the bodies are comparatively well preserved

18. General principles of treatment of acute poisoning Household emetics Stomach tube Chelating agents If the poison is known, specific treatment must be instituted. if not, treatment is given on general lines. The main aim of treatment is to help the patient to stay alive by attention to respiration and circulation.

19. Continuous… the details will vary according to the portal of entry of the poison (inhalation, injection, contact or ingestion) the main objects include: Removal of unabsorbed poison from the body Use of antidotes Elimination of the absorbed poison Treatment of general symptoms Maintenance of the patient’s general condition

20. Removal of unabsorbed poison from the body Depending upon the route of entry, the following principles should be kept in mind Inhaled : patient removed to fresh air and artificial respiration commenced at once. The air passages should be kept free from mucous by postural drainage and aspiration. Injected poisons : if the poison has been injected, a tight tourniquet should be applied proximal to the point of injection. It must be released every 10 minutes for 1 minute to prevent gangrene. The wound may be excised and poison removed by suction, and/ or neutralized chemically such as snake bite, insect bite Contact poison : if the poison be spilled or sprayed on skin, eye or wound, or be inserted to vagina, rectum or urinary bladder, the best way to treat it is to wash it out with plain warm water and/ or to neutralize it by a suitable antidote. Ingested poison : the object is to remove from the stomach as soon and as much of the poison as possible. For this purpose, (1) vomiting(emesis) may be induced and or the (2) stomach washed out (gastric lavage)

21. Use of antidote Antidotes are remedies which counteract or neutralize the effect of poisons without causing appreciable harm to the body. They need to be used because: The poison may not have been completely removed by emesis or gastric lavage or these procedures are contraindicated, The poison already absorbed The poison has been administered by route other than ingestion

22. Antidote classification They can be classified into four groups, in accordance with their mode of action: Mechanical or physical Chemical Physiological or pharmacological Universal

23. Mechanical or physical antidote These are substances which impede the absorption of poisons by their presence. These are few in number Such as: Demulcents: fats, milk, egg, albumin etc Bulky food: Banana Activated charcoal: useful in adsorbing alkaloidal poisons, such as strychnine

24. Chemical antidotes These are substances which act their either by direct chemical action or by oxidizing the poison to form a non toxic or an insoluble compound. Some of the examples are as follow: Dilute acetic acid or vinegar neutralizes alkalis by direct chemical action Dilute alkalis, e.g. milk of magnesia will neutralize acids

25. Physiological or pharmacological antidote These agents produce effects which are opposite to that of the poison Examples of physiological antagonists are: atropine for pilocarpine , diazepam for strychnine, naloxone for morphine, atropine and oximes for organ phosphorus compounds, N- acetyl cysteine for acetaminophen, and mazicon for benzodiazepins . Desferrioxamine chelates iron. It is chiefly valuable in the treatment of acute iron poisoning. EDTA(ethylene diamine tetra acetate) is a chelating agent and is effective in lead, mercury and copper poisoning.

26. Universal antidote I t is antidote that is used in those cases where the nature of the ingested poisons is unknown or where it is suspected that a combination of two or more poisons has been taken. As follow:

27. Elimination of the absorbed poison This may be achieved by accelerating its excretion especially in the urine. Ample amounts of fluid should be administered to maintain adequate diuresis. Hemodialysis has been employed for removing barbiturates, boric acid, glutethimide , methyl alcohol, salicylates and thiocyanates from the blood. Haemoperfusion : is superior to hemodialysis for removal lipid soluble drugs. Exchange transfusion is only feasible with small children and has been applied to poisonings by salicylates, barbiturates, iron salts, CO A new alternative to lavage, dialysis and hemoperfusion is whole bowel irrigation.

28. Treatment of general symptoms The treatment of symptoms should be applied as indication arise Morphine should be given for pain Oxygen or artificial respiration for respiratory failure Cardiac stimulants for failing circulation Anesthetics, barbiturates, or diazepam for convulsion Saline infusion may be useful to counteract dehydration as well as to enhance diuresis to excrete toxic substances. Administration of glucose will combat depletion of liver glycogen The restoration of potassium or sodium balance may be necessary

29. Autopsy Autopsy(autos=self; opis =view) literally means to see for oneself. A medicolegal autopsy (necropsy) or post mortem examination( necros =dead; opis =view) (post=after; mortem=death) is a special type of scientific examination of a dead body carried out under the laws of the state mainly for the protection of its citizens and to assist the identification and prosecution of the guilty in cases of unnatural deaths

30. Medicolegal autopsy in poisoning This should be carried out in the manner already described in forensic medicine Determine the identity of person To determine The cause of death: natural or un natural If natural: whether suicide, homicide or accident In all cases but more important in homicide, to collect and document trace evidence, if any left by the accused on victim To identify the weapon, person or poison responsible for death In case of fatal wounding, to determine the volitional activity possible after such trauma

31. Continuous… To estimate the approximate time since death In case of newly born infants, to determine the question of live birth and viability of the child To restore the body to the best possible cosmetic appearance before it is released to the relatives

32. The essential requirements of a medicolegal autopsy are: It should be performed by a registered(licensed) medical practitioner having special training or experience in forensic medicine(forensic pathology) The examination should be meticulous and complete; and one should routinely record all positive findings and important negative one, e.g. absence of skull fracture in case of head injury; absence of defense injuries in a case of struggle; or condition of coronary arteries in a case of sudden natural death All information must be preserved by written records including relevant photographs, radiographs, sketches on body diagrams, measurements and weight Trace evidential material when recovered should be properly documented and preserved From the data so obtained, the medical officer should provide a factual and objective medical report for the law enforcement agencies keeping in mind that he may have to explain his findings and opinions at the time cross examination in a court law It is necessary that those who undertake medicolegal autopsies are familiar with the appearance of healthy and diseased organs.

33. Postmortem examination The smell from the clothes and body, forth at nose and mouth, stains about the lips and chin, colour of skin and postmortem lividity , marks of injection, and condition of natural orifices may help to diagnose poisoning. The alimentary system should be examined very carefully since signs of corrosives and irritant poisons are likely to be found therein. These signs may manifest as hyperemia, softening, ulceration, and perforation.

34. Preservation and dispatch of viscera for chemical analysis The stomach, stomach contents, small intestine, and small intestine contents should be preserved in one wide mouthed glass bottle; pieces of liver, spleen and kidney, in another bottle; and urine in the third bottle. When additional material is required to be sent, it should be dispatched in separate bottles. Brain in one bottle. Blood should be sent in a vial. The bottles and vials required for preservation are normally supplied by the office of the director, forensic science laboratory(FSL)/ government medical stores. Chemical analysis: the most important proof of poisoning is the analytical detection of poison in the parenchyma of the organs of the body.