Toxicology Chapter # 8. Toxicology Introduction What is Toxicology? What is Toxicology? The History...

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Transcript of Toxicology Chapter # 8. Toxicology Introduction What is Toxicology? What is Toxicology? The History...

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Toxicology Chapter # 8 Slide 2 Toxicology Introduction What is Toxicology? What is Toxicology? The History of Toxicology. The History of Toxicology. What is Toxic? What is Toxic? Toxicity and Risk. Toxicity and Risk. 7 Classes of Toxins. 7 Classes of Toxins. Types of Toxins. Types of Toxins. Entry Routes and Their Effects. Entry Routes and Their Effects. Dose-Response Relationships. Dose-Response Relationships. Measuring Toxicity. Measuring Toxicity. Slide 3 Toxicology What is Toxicology? What is Toxicology? Commonly called the study of poisons.Commonly called the study of poisons. Most literature agrees that the common definition is too narrow.Most literature agrees that the common definition is too narrow. Toxicology has evolved into several sub-disciplines:Toxicology has evolved into several sub-disciplines: Forensic Clinical Environmental Industrial, etc. Slide 4 Toxicology History of Toxicology: History of Toxicology: Early man divided substances into food or poisons.Early man divided substances into food or poisons. Poisons extracted from plants and venoms used.Poisons extracted from plants and venoms used. Ebers papyrus (1500 B.C.) - 1st record of >800 poison recipes including hemlock, aconite, & heavy metals.Ebers papyrus (1500 B.C.) - 1st record of >800 poison recipes including hemlock, aconite, & heavy metals. Middle Ages (300 B.C. - 1300 A.D.) Greeks & Romans credited as advanced societies that knew about & used poisons:Middle Ages (300 B.C. - 1300 A.D.) Greeks & Romans credited as advanced societies that knew about & used poisons: Hypocrates, Aristotle, Theophrastus, Diosorides Modern Age (1400 A.D. - Now) European & US toxicologists lead:Modern Age (1400 A.D. - Now) European & US toxicologists lead: Paracelsus, Pott, Orfila Slide 5 Toxicology 7 Classes of Toxins: 7 Classes of Toxins: Asphyxiants:Asphyxiants: Simple Chemical n Blood n Tissue n Paralyzers CorrosivesCorrosives IrritantsIrritants Slide 6 Toxicology 7 Classes of Toxins, Continued: 7 Classes of Toxins, Continued: SensitizersSensitizers CarcinogensCarcinogens MutagensMutagens TeratogensTeratogens Slide 7 Toxicology Asphyxiants: Asphyxiants: Simple - displace O 2 so that insufficient concentration for respiration leads to suffocation (e.g., CH 4 & N 2 ). 19.5% O 2 required by OSHA.Simple - displace O 2 so that insufficient concentration for respiration leads to suffocation (e.g., CH 4 & N 2 ). 19.5% O 2 required by OSHA. Rule of Thumb - a contaminant will deplete O 2 content by 1/5 its concentration. Slide 8 Toxicology Asphyxiants, Continued: Asphyxiants, Continued: Chemical - (toxicity not directly related to O 2 depletion):Chemical - (toxicity not directly related to O 2 depletion): Blood - biochemically react w/RBC inhibiting O 2 up-take (e.g., CO & C 6 H 5 NH 2 ). Tissue - carried to tissues by RBC where they react to inhibit O 2 up-take (e.g., HCN). Paralyzers - react biochemically to depress CNS components that control respiration (e.g., H 2 S & C 2 H 5 OH). Slide 9 Toxicology Corrosives: Corrosives: Destroys tissue by chemically reacting with it.Destroys tissue by chemically reacting with it. Reaction often depletes cells of their water and also causes thermal burns from exothermic reactions w/skin moisture (e.g., HF, HNO 3, H 2 SO 4, etc.).Reaction often depletes cells of their water and also causes thermal burns from exothermic reactions w/skin moisture (e.g., HF, HNO 3, H 2 SO 4, etc.). Slide 10 Toxicology Irritants: Irritants: Exposures cause temp inflammation of mucous membranes, eyes, skin, upper respiratory tract.Exposures cause temp inflammation of mucous membranes, eyes, skin, upper respiratory tract. H2O solubility affects where they react:H2O solubility affects where they react: High - reacts with 1st moisture encountered eyes, nose, throat. Moderate - reacts with upper respiratory tract & lungs. Low - delayed reacts in alveolar region. Slide 11 Toxicology Sensitizers (e.g., TDI &, CHO): Sensitizers (e.g., TDI &, CHO): Cause an allergic-type reaction after repeated &/or extended exposures.Cause an allergic-type reaction after repeated &/or extended exposures. Allergic reacts commonly includes dermatitis-like conditions - small pimples &/or watery blisters that dont always appear at site of contact. Allergic reacts can also include itching, tingling &/or pain in joints & extremities and upper respiratory tract irritation. Some chemicals can sensitize people to light.Some chemicals can sensitize people to light. Once exposed sufficiently, the victim gets sunburned &/or develops rashes more easily. Removal of the patient from future contact with the sensitizer is the only way to prevent future attacks with out drugs.Removal of the patient from future contact with the sensitizer is the only way to prevent future attacks with out drugs. Slide 12 Toxicology Carcinogens: Carcinogens: Cause cancer (uncontrolled growth of abnormal cells) usually over substantial repeated exposures, but possibly after small &/or one-time exposures.Cause cancer (uncontrolled growth of abnormal cells) usually over substantial repeated exposures, but possibly after small &/or one-time exposures. Differ from other toxins because: (1) very small doses can cause cancer; & (2) adverse health effects are usually not recognizable until years have passed.Differ from other toxins because: (1) very small doses can cause cancer; & (2) adverse health effects are usually not recognizable until years have passed. Multiple theories on cancer generation include the one-hit theory - one molecule of a carcinogen causing cancer.Multiple theories on cancer generation include the one-hit theory - one molecule of a carcinogen causing cancer. Slide 13 Toxicology Carcinogens, Continued: Carcinogens, Continued: Example: C 6 H 6, asbestos.Example: C 6 H 6, asbestos. Responders must use the highest level of personal protection when working with a carcinogen.Responders must use the highest level of personal protection when working with a carcinogen. Mutagens: Mutagens: Toxins that impart inheritable changes to the DNA & RNA of exposed persons (e.g., C 6 H 6 & H 2 O 2 ).Toxins that impart inheritable changes to the DNA & RNA of exposed persons (e.g., C 6 H 6 & H 2 O 2 ). Some mutagens can cause cancers, but most result in deformities &/or biochemical deficiencies.Some mutagens can cause cancers, but most result in deformities &/or biochemical deficiencies. Slide 14 Toxicology Teratogens: Teratogens: Toxins that cause birth defects in unborn children.Toxins that cause birth defects in unborn children. Depending on when exposures occur (embryonic or fetal stages), adverse effects can be limb or cognitive deformities (e.g., ionizing radiation).Depending on when exposures occur (embryonic or fetal stages), adverse effects can be limb or cognitive deformities (e.g., ionizing radiation). Slide 15 Toxicology Risk: Important Considerations: Risk: Important Considerations: Describes the chance of an event resulting in an uncontrolled release, exposure, contamination, &/or fire.Describes the chance of an event resulting in an uncontrolled release, exposure, contamination, &/or fire. Is often influenced by local incident site conditions, environmental conditions, and physical & chemical properties of the agent(s).Is often influenced by local incident site conditions, environmental conditions, and physical & chemical properties of the agent(s). Caveat: hazardous materials may fit into 2 or more classes of toxins.Caveat: hazardous materials may fit into 2 or more classes of toxins. Slide 16 Toxicology Risk: Important Considerations, Continued: Risk: Important Considerations, Continued: When responding to a HazMat incident, agent(s) toxicity and the risk of exposure, explosion, reaction, &/or fire it poses must be considered to accurately evaluate the hazard.When responding to a HazMat incident, agent(s) toxicity and the risk of exposure, explosion, reaction, &/or fire it poses must be considered to accurately evaluate the hazard. The risk of the outcomes differ from & are independent of the agents toxicity.The risk of the outcomes differ from & are independent of the agents toxicity. All substances are poisons. The toxicity depends on the dose.All substances are poisons. The toxicity depends on the dose. Slide 17 Toxicology Routes of Entry: Routes of Entry: InhalationInhalation DermalDermal ParenteralParenteral IngestionIngestion Slide 18 Toxicology Inhalation: Inhalation: Lungs are the organ where gas exchange vital to respiration occurs.Lungs are the organ where gas exchange vital to respiration occurs. Large surface area make lungs more susceptible to exposure in comparison to skin.Large surface area make lungs more susceptible to exposure in comparison to skin. Rate of respiration is most important factor because it is directly related to rate of absorption.Rate of respiration is most important factor because it is directly related to rate of absorption. Slide 19 Toxicology Inhalation, Continued: Inhalation, Continued: Toxic Effects of Inhalation:Toxic Effects of Inhalation: Lung cancer. Fibrosis - scar tissue that restricts lung capacity (e.g., NH 3 ). Sensitization - short-term constriction of air ways may develop into long-term pulmonary disease (e.g., TDI & SO 2 ). Irritation - constriction of airways may lead to infection or edema. Slide 20 Toxicology Dermal Entry: Dermal Entry: Skin is a layer of tissue covering the outer surface of the body:Skin is a layer of tissue covering the outer surface of the body: Is the largest organ in the human body. Composed of 3 layers - epidermis, dermis, & subcutaneous. Is not a protective barrier against hazardous materials. Amount of Toxin Absorbed & Rate Depend on:Amount of Toxin Absorbed & Rate Depend on: Exposure time.