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Chapter 8 Toxicology: Poisons and Alcohol

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  1. Chapter 8Toxicology:Poisons and Alcohol “All substances are poisons. There is none which is not. The right dose differentiates a poison and remedy.” —Paracelsus (1495-1541). Swiss physician and chemist

  2. Toxicology and Alcohol • A quantitative approach to toxicology. • The danger of using alcohol. Students will learn: Kendall/Hunt Publishing Company

  3. Toxicology and Alcohol Students will be able to: • Discuss the connection of blood alcohol levels to the law, incapacity, and test results. • Understand the vocabulary of poisons. • Design and conduct scientific investigations. • Use technology and mathematics to improve investigations and communications. • Identify questions and concepts that guide scientific investigations. • Communicate and defend a scientific argument. Kendall/Hunt Publishing Company

  4. Was Paracelsus Right? • Hormesis —refers to the concept promoted by Paracelsus: that substances that kill at high doses are actually beneficial at low doses— the poison is in the dosage. • This appears to be true for many substances: oxygen, water, aspirin, alcohol, etc. Kendall/Hunt Publishing Company

  5. Historical Perspective of Poisoners • Olympias—a famous Greek poisoner • Locusta—personal poisoner of Emperor Nero • Lucretia Borgia—father was Pope Alexander VI • Madame GiuliaToffana—committed over 600 successful poisonings, including two Popes. • HieronymaSpara—formed a society to teach women how to murder their husbands • Madame de Brinvilliers and CatherineDeshayes—French poisoners. AND many others through modern times. Kendall/Hunt Publishing Company

  6. People of Historical Significance Mathieu Orfila—known as the father of forensic toxicology, published in 1814 “Traite des Poisons” which described the first systematic approach to the study of the chemistry and physiological nature of poisons. Kendall/Hunt Publishing Company

  7. Toxicology Toxicology—the study of the adverse effects of chemicals or physical agents on living organisms. Types: • Environmental Toxicology—air, water, soil • Consumer Toxicology—foods, cosmetics, drugs • Medical(Clinical) Toxicology—prescription medication • Forensic Toxicology —use of toxicology to aid in the investigation of death, poisoning and drug use. Kendall/Hunt Publishing Company

  8. Forensic Toxicology • Postmortem—medical examiner or coroner • Criminal—motor vehicle accidents (MVA) • Workplace—drug testing • Sports—human and animal • Environment—industrial, catastrophic, terrorism Kendall/Hunt Publishing Company

  9. Toxins • Toxin—a substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with enzymes and receptors. (Usually a naturally produced substance that kills rapidly in small quantities) Kendall/Hunt Publishing Company

  10. Toxic Substances Toxic substances may: • Be a cause of death • Contribute to death • Cause impairment • Explain behavior Poison hemlock is a plant related to the carrot. It contains alkaloids that negatively affect the nervous system Kendall/Hunt Publishing Company

  11. The Severity of the Problem “If all those buried in our cemeteries who were poisoned could raise their hands, we would probably be shocked by the numbers.” —John Harris Trestrail, “Criminal Poisoning” Kendall/Hunt Publishing Company

  12. Elements of Toxicity • Dosage • many substances are only lethal in high dosages • The chemical or physical form of the substance • Arsenic is not very poisonous in its natural form (metal); but arsenic trioxide or arsenic gas is very poisonous. • The mode of entry into the body • some substances are most poisonous if swallowed; others must be injected, inhaled or absorbed Kendall/Hunt Publishing Company

  13. Elements of Toxicity • Body weight and physiological conditions of the victim, including ageand sex • Blood alcohol content is directly related to body weight • Infants and elderly are more susceptible to most toxins • The time period of exposure • Sometimes small amounts ingested over time create a tolerancefor the toxin • Chronic exposure (larger amounts over time) can create serious medical problems • Acute toxicity—very large dose causing immediate problems, including death Kendall/Hunt Publishing Company

  14. Elements of Toxicity • The presence of other chemicals in the body or in the dose • Synergism: combination of two chemicals increases the effects of both in the system • Ex: antihistamine and alcohol • Antagonism: combination of two chemicals decreases the effects of both in the system • Ex: Chelating agent and arsenic Kendall/Hunt Publishing Company

  15. Lethal Dose • LD50—refers to the dose of a substance that kills half the test population, usually within four hours • (Note: test population is usually mice or rats) • Expressed in milligrams of substance per kilogram of body weight. A correlation is then made to humans based on the body weight data. • However, estimating lethal doses for humans is often complicated by the fact that resistance to certain chemicals can differ greatly between species Kendall/Hunt Publishing Company

  16. Toxicity Classes Kendall/Hunt Publishing Company

  17. LD50 Update • Because a single test may kill as many as 100 animals, the U.S. and other members of the Organization for Economic Cooperation and Development agreed in December 2000 to phase out the LD50 test in favor of alternatives that greatly reduce (or even eliminate) deaths of the test animals. Kendall/Hunt Publishing Company

  18. Federal Regulatory Agencies • To ensure public safety, the federal government has created several regulatory agencies related to toxic substances: • Food and Drug Administration (FDA)—deals with pharmaceuticals, food additives, and medical devices • Environmental Protection Agency (EPA)—works with agricultural and industrial chemicals released to the environment • Consumer Product Safety Commission—concerned with toxins in consumer products • Department of Transportation (DOT)—watches shipment of toxic chemicals • Occupational Safety and Health Administration (OSHA)—concerned with exposure to chemicals in the workplace Kendall/Hunt Publishing Company

  19. Symptoms of Various Typesof Poisoning Type of PoisonSymptom/Evidence • Caustic Poison (lye) Characteristic burns around the lips and mouth of the victim • Carbon Monoxide Red or pink patches on the chest and thighs, unusually bright red lividity • Sulfuric acid Black vomit • Hydrochloric acid Greenish-brown vomit • Nitric acid Yellow vomit • Phosphorous Coffee brown vomit. Onion or garlic odor • Cyanide Burnt almond odor • Arsenic, Mercury Pronounced diarrhea • Methyl (wood) or Nausea and vomiting, unconsciousness, Isopropyl (rubbing) alcohol possibly blindness Kendall/Hunt Publishing Company

  20. Form Common color Characteristic odor Solubility Taste Common sources Lethal dose Mechanism Possible methods of administration Time interval of onset of symptoms. Symptoms resulting from an acute exposure Symptoms resulting from chronic exposure Disease states mimicked by poisoning Notes relating to the victim Specimens from victim Analytical detection methods Known toxic levels Notes pertinent to analysis of poison List of cases in which poison was used Critical Informationon Poisons —John Trestrail from “Criminal Poisoning” Kendall/Hunt Publishing Company

  21. To Prove a Case • Prove a crime was committed • Motive • Intent • Access to poison • Access to victim • Death was caused by poison • Death was homicidal Kendall/Hunt Publishing Company

  22. Forensic Autopsy Look for: • Irritated tissues • Characteristic odors • Mees lines—single transverse white bands on nails. Order toxicological screens • Postmortem concentrations should be done at the scene for comparison • No realistic calculation of dose can be made from a single measurement Kendall/Hunt Publishing Company

  23. Blood Urine Vitreous Humor of Eyes Bile Gastric contents Liver tissue Brain tissue Kidney tissue Hair/nails Human Specimens for Analysis Kendall/Hunt Publishing Company

  24. Alcohol—Ethyl Alcohol (C2H5OH) • Most abused drug in America • About 40% of all traffic deaths are alcohol-related • Toxic—affecting the central nervous system, especially the brain • Colorless liquid, generally diluted in water • Acts as a depressant • Alcohol appears in blood within minutes of consumption; 30-90 minutes for full absorption • Detoxification—about 90% is done in the liver at a rate of about 0.015% per hour. • About 5% is excreted unchanged in breath, perspiration and urine Kendall/Hunt Publishing Company

  25. Rate of Absorption Depends on: • amountof alcohol consumed • the alcohol content of the beverage • time taken to consume it • quantity and type of food present in the stomach • physiologyof the consumer Kendall/Hunt Publishing Company

  26. BACBlood Alcohol Content • Expressed as percent weight per volume of blood • Legal limits in all states is 0.08% (0.08 grams of pure alcohol for every 100ml of blood) • Parameters influencing BAC: • Body weight • Alcoholic content • Number of beverages consumed • Time between consumption Kendall/Hunt Publishing Company

  27. BAC • Burn off rate of 0.015% per hour but can vary: • Male BAC male = 0.071 x (oz) x (% alcohol) body weight • Female BAC female = 0.085 x (oz) x (% alcohol) body weight Kendall/Hunt Publishing Company

  28. Sample Problem • What would be the approximate BAC of a 185 pound man who has consumed three shots (1.5 oz.each) of Jack Daniels (80 proof = 40% alcohol) in an hour? BACmale = 0.071 x 4.5 x 40 = 0.07 185 Kendall/Hunt Publishing Company

  29. Henry’s Law • Henry’s Law provides the scientific basis for the breath test check for sobriety. • When a volatile chemical is dissolved in a liquid and is brought to equilibrium with air, there is a fixed ratio between the concentration of the volatile compound in the air and its concentration in the liquid; this ratio is constant for a given temperature. THEREFORE, the concentration of alcohol in breath is proportional to that in the blood. • This ratio of alcohol in the blood to alcohol in the alveolar air is approximately 2100 to 1. In other words 1 ml of blood will contain nearly the same amount of alcohol as 2100 ml of breath. Kendall/Hunt Publishing Company

  30. Field Tests • Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another test is justified. • Psychophysical tests—3 Basic Tests • Horizontal gaze nystagmus (HGN): follow a pen or small flashlight, tracking left to right with one’s eyes. In general, wavering at 45 degrees indicates 0.10 BAC. • Nine Step walk and turn (WAT): comprehend and execute two or more simple instructions at one time. • One-leg stand (OLS): maintain balance, comprehend and execute two or more simple instructions at one time. Kendall/Hunt Publishing Company

  31. The Breathalyzer • Invented in 1954 • More practical in the field • Collects and measures alcohol content of alveolar breath • Breath sample mixes with 3 ml of 0.025 % K2Cr2O7 in sulfuric acid and water 2K2Cr2O7 + 3C2H5OH+ 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11 H2O • Potassium dichromate is yellow, as concentration decreases its light absorption diminishes so the breathalyzer indirectly measures alcohol concentration by measuring light absorption of potassium dichromate before and after the reaction with alcohol Kendall/Hunt Publishing Company

  32. Generalizations • During absorption, the concentration of alcohol in arterial blood will be higher than in venous blood. • Breath tests reflect alcohol concentration in the pulmonary artery. • The breathalyzer also can react with acetone (as found with diabetics), acetaldehyde, methanol, isopropyl alcohol, and paraldehyde, but these are toxic and their presence means the person is in serious medical condition. • Breathalyzers now use an infrared light absorption device with a digital read-out. Prints out a card for a permanent record. Kendall/Hunt Publishing Company

  33. People in the News John Trestrail is a practicing toxicologist who has consulted on many criminal poisoning cases. He is the founder of the Center for the Study of Criminal Poisoning in Grand Rapids, Michigan which has established an international database to receive and analyze reports of homicidal poisonings from around the world. He is also the director of DeVos Children’s Hospital Regional Poison Center. In addition, he wrote the book, Criminal Poisoning, used as a reference by law enforcement, forensic scientists and lawyers. Kendall/Hunt Publishing Company

  34. More Information Read more about Forensic Toxicology from Court TV’s Crime Library at: http://www.crimelibrary.com/criminal_mind/forensics/toxicology/2.html Kendall/Hunt Publishing Company