Toxicology PDF

Toxicology is derived from two greek words : ‘toxikon meaning poison and ‘logos’ meaning study It is the study of adverse effect of chemicals or poisons on the biological systems It includes ✓Identification of pois...

Toxicology is derived from two greek words : ‘toxikon meaning poison and ‘logos’ meaning study It is the study of adverse effect of chemicals or poisons on the biological systems It includes ✓Identification of poisons ✓Their chemical properties ✓Their biological effects ✓Treatment of disease conditions that they may cause Introduction Toxic effects of poisons may be expressed in several ways: ✓Changes in growth, ✓development, reproduction ✓pharmacokinetic responses, pathology , biochemistry ✓physiology and behaviour.  Descriptive toxicologist is concerned directly with toxicity testing, which provides information for safety evaluation and regulatory requirements (drugs and food additives). Mechanistic toxicologist identifying and understanding the mechanisms by which chemicals exert toxic effects on living organisms. Forensic toxicology is concerned primarily with the medicolegal aspects of the harmful effects of chemicals on human and determining their circumstances in a post-mortem investigation. Different Clinical toxicology is concerned with disease caused by or uniquely associated with toxic substances. areas of Environmental toxicology focuses on the impact of chemical toxicology pollutants in the environment on biological organisms, most commonly on nonhuman organisms such as fish, birds and terrestrial animals.  Poison and Toxin: Poison is any solid, liquid or gas that can interfere with life processes of cells of the organism and can exert physiological or psychological disorders Another term used for poison is toxicant – any agent capable of producing deleterious response in a biological system Toxins originate from biological processes are Toxin and classified as biotoxins Toxicosis describes the disease state that results Poison from exposure to poison or poisoning and intoxication.  Toxicologist: Studies the nature of adverse effect of toxins at molecular, cellular, organ, organism or even community level by understanding how these agents affect the system and how the system affects the agents Toxicity is the amount of a poison that under a specific set of conditions causes toxic effects or results in detrimental biological conditions. Toxin and Expressed as milligrams (mg) of toxicant per kilogram (kg) body weight that will produce a Poison defined biological effect. Dosage: total amount of toxicant per unit of body weight Dose: total amount of toxicant received by a person Toxic agents Toxin: generally, refers to toxic substances that are produced by biological as plants, animals, fungi or bacteria Toxic agents are classified in terms of Their target Effects (cancer, Use (pesticide, Source (animal organs (liver, mutation, liver solvent) and plant toxins) kidney) injury) Poisoning potential Chemical stability or General chemical Physical state (extremely toxic, reactivity (explosive, structure (gas, dust, liquid) very toxic, slightly flammable) (aromatic amine) toxic). Biochemical mechanisms of action (e.g. alkylating agent) Poison Poison is a substance which, when introduced into the living body, is capable of producing deleterious effects, ill health or death. Types of Poisoning: Ø Acute Poisoning Ø Chronic Poisoning Ø Sub-acute Poisoning Ø Fulminant Poisoning Poisoning episodes may be classified into four types: ✓ Accidental poisoning: Accidental poisoning may occur in young or older children and adults particularly as a result of mishaps at school or work e.g. Paracetamol is a common cause of accidental poisoning in young children. ✓ Suicidal poisoning: the commonest form of poisoning in adults and accounts for at least 95% of all poisoning admission to hospital. Such patients intentionally take poisons or overdoses of drugs. ✓ Homicidal poisoning: killing of a human being by another human being by administering poisonous substance deliberately ✓ Non-accidental poisoning: May present as an unusual illness rather than poisoning (Child abuse).  There are four categories of action of poisons—(i) local action, (ii) remote action, (iii) local and remote actions, and (iv) general action. ✓Local action (Corrosives): Local action means direct action on the affected site of the body. Examples include irritation and inflammation in strong mineral acids and alkalis, congestion and inflammation by irritants, the effect on motor and sensory nerves, etc. Toxicant’s or ✓Remote action: Remote action affects the person due to poison absorption of that poison into the system of that person. For classification example, alcohol is absorbed in the system and then it affects the person. ✓Local and remote actions (irritant metallic ): Some poisons can affect both local and remote organs. Thus, they not only affect the area with contact to the poison but also cause toxic effect after absorption into the system, for example, oxalic acid. ✓General action: General action means the absorbed poison affects more than one system of the body, for example, mercury, arsenic, etc. Toxicant’s or poison classification