Presentation on theme: "Dr M Tamour Ashiq MBBS. Rawalpindi Medical College M Phil Microbiology Rawalpindi Medical College Post-Graduate Diploma in Occupational Health and Safety."— Presentation transcript:
Dr M Tamour Ashiq MBBS. Rawalpindi Medical College M Phil Microbiology Rawalpindi Medical College Post-Graduate Diploma in Occupational Health and Safety Quality Auditor ISO-9001:2008 IRKA-UK Certified.
Toxicology What is toxicology? The study of the effects of substances in livings. Poisonous substances are produced by plants, animals, or bacteria. Phytotoxins Zootoxins Bacteriotoxins
Definitions Toxicant: Any chemical that can potentially produce harm is toxicant, (e.g. Lead, Pesticides, Sodium cyanide, Benzene). Toxin: Chemicals that are produce by living organisms, (e.g. Rattlesnake venom or poisonous mushrooms). Poison: Any substance that when ingested, inhaled, or absorbed or when applied to, injected into or developed within the body in relatively small amounts may, by its chemical action, cause death or injury. Toxic substance: Can be a particular chemical or a mixture of chemicals that collectively have toxic properties, (e.g. Asbestos, Lead chloride).
Introduction Toxicology is the oldest scientific discipline, as the earliest humans had to recognize which plants were safe to eat. Most exposure of humans to chemicals is via naturally occurring compounds consumed from food plants.
You Know ? 92% of all poisonings happen at home. The household products implicated in most poisonings are: cleaning solutions, fuels, medicines, and other materials such as glue and cosmetics. Certain animals secrete a poison called venom, usually injected with a bite or a sting, and others animals harbor infectious bacteria. Some household plants are poisonous to humans and animals.
History 2700 B.C. - Chinese journals: plant and fish poisons 1200-1900 B.C. - Egyptian documents that had directions for collection, preparation, and administration of more than 800 medicinal and poisonous recipes. 800 B.C. - India - Hindu medicine includes notes on poisons and antidotes. 50-100 A.D. - Greek physicians classified over 600 plant, animal, and mineral poisons.
History 50- 400 A.D. - Romans used poisons for executions and assassinations. Avicenna (A.D. 980-1036) Islamic authority on poisons and antidotes. 1200 A.D. - Spanish rabbi Maimonides writes first-aid book for poisonings, Poisons and Their Antidotes
History Swiss physician Paracelsus(1493-1541) credited with being the father of modern toxicology. All substances are poisons: there is none which is not a poison. The right dose differentiates a poison from a remedy. Dose Response relationship. Mercury for the treatment of Syphilis.
The Dose Makes the Poison An apparently nontoxic chemical can be toxic at high doses. (Too much of a good thing can be bad). Highly toxic chemicals can be life saving when given in appropriate doses. (Poisons are not harmful at a sufficiently low dose).
Lethal Doses Approximate Lethal Doses of Common Chemicals (Calculated for a 160 lb. human from data on rats) ChemicalLethal Dose Sugar (sucrose)3 quarts Alcohol(ethyl alcohol)3 quarts Salt (sodium chloride)1 quart Herbicide (2, 4-D)one half cup Arsenic (arsenic acid)1-2 teaspoons Nicotineone half teaspoon Food poison (botulism)microscopic
describing "asthma" in bakers, miners, farmers, gliders, tinsmiths, glass-workers, tanners, millers, grain-sifters, stonecutters, ragmen, runners, riders, porters, and professors. Ramazzini outlined health hazards of the dusts, fumes, or gases that such workers inhaled. The bakers and horse riders described by Ramazzini would today probably be diagnosed as suffering from allergen-induced asthma. The lung diseases suffered by most of the other workers would now be classified as "pneumoconiosis," a group of dust-related chronic diseases. History Italian physician Ramazzini (1713) published De Morbis Artificum Diatriba (Diseases of Workers)
20th Century Rachel Carson - alarmed public about dangers of pesticides in the environment. History
Spanish physician Orfila (1815) established Forensic Toxicology as a distinct scientific discipline. Book :Traite de Poisons History
Catherine de Medici (1519-1589) Queen of France Poisoning skills Treating poor and sick people with poison. Dose response Signs and symptoms Descriptive toxicologist.
Paul Ehrlich: developed staining procedures to observe cell and tissues and pioneered the understanding of how toxicants influence living organisms (20 th century). History