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Chapter 8 Toxicology: Poisons and Alcohol

Chapter 8 Toxicology: Poisons and Alcohol

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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 Definition—the study of the adverse effects of chemicals or physical agents on living organisms.

  3. Toxicology Types: • Environmental—air, water, soil • Consumer—foods, cosmetics, drugs • Medical, clinical, forensic

  4. Forensic Toxicology • Postmortem—medical examiner or coroner • Criminal—motor vehicle accidents (MVA) • Workplace—drug testing

  5. Forensic Toxicology • Sports—human and animal • Environment—industrial, catastrophic, terrorism

  6. Toxicology Toxic substances may: • Contribute to death • Be a cause of death • Cause impairment • Explain behavior

  7. 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”

  8. Aspects of Toxicity • Dosage • The chemical or physical form of the substance • The mode of entry into the body • Body weight and physiological conditions of the victim, including age and sex

  9. Aspects of Toxicity • The time period of exposure • The presence of other chemicals in the body or in the dose

  10. Lethal Dose • LD50—refers to the dose of a substance that kills half the test population, usually within four hours • Expressed in milligrams of substance per kilogram of body weight

  11. Toxicity Classes

  12. Federal Regulatory Agencies • Food and Drug Administration (FDA) • Environmental Protection Agency (EPA) • Consumer Product Safety Commission • Department of Transportation (DOT) • Occupational Safety and Health Administration (OSHA)

  13. 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

  14. Symptoms of Various Typesof Poisoning Type of PoisonSymptom/Evidence • Phosphorous Coffee brown vomit. Onion or garlic odor • Cyanide Burnt almond odor • Arsenic, Mercury Pronounced diarrhea • Methyl (wood) or Nausea and vomiting, Isopropyl (rubbing) unconsciousness, alcohol possibly blindness

  15. Form Common color Characteristic odor Solubility Taste Common sources Critical Informationon Poisons —John Trestrail from “Criminal Poisoning”

  16. Mechanism Possible methods of administration Time interval of onset of symptoms. Symptoms resulting from an acute exposure Symptoms resulting from chronic exposure Critical Informationon Poisons —John Trestrail from “Criminal Poisoning”

  17. Disease states mimicked by poisoning Notes relating to the victim Specimens from victim Analytical detection methods Critical Informationon Poisons —John Trestrail from “Criminal Poisoning”

  18. 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”

  19. To Prove a Case • Prove a crime was committed • Motive • Intent • Access to poison

  20. To Prove a Case • Access to victim • Death was caused by poison • Death was homicidal

  21. Forensic Autopsy Look for: • Irritated tissues • Characteristic odors • Mees lines—single transverse white bands on nails.

  22. Forensic Autopsy 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

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

  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

  25. Alcohol—Ethyl Alcohol (C2H5OH) • Colorless liquid, generally diluted in water • Acts as a depressant • Alcohol appears in blood within minutes of consumption; 30-90 minutes for full absorption

  26. Alcohol—Ethyl Alcohol (C2H5OH) • Detoxification—about 90% in the liver • About 5% is excreted unchanged in breath, perspiration and urine

  27. Rate of Absorption Depends on: • amount of alcohol consumed • the alcohol content of the beverage • time taken to consume it • quantity and type of food present in the stomach • physiology of the consumer

  28. BACBlood Alcohol Content • Expressed as percent weight per volume of blood • Legal limits in all states is 0.08% • Parameters influencing BAC: • Body weight • Alcoholic content • Number of beverages consumed • Time between consumption

  29. 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

  30. Henry’s Law • 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.

  31. Henry’s Law • 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.

  32. Field Tests • Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another test is justified.

  33. Field Tests • Psychophysical test— • 3Basic 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.

  34. Field Tests • 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.

  35. The Breathalyzer • 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

  36. The Breathalyzer • 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

  37. 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.

  38. Generalizations • 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.

  39. Generalizations • Breathalyzers now use an infrared light absorption device with a digital read-out. Prints out a card for a permanent record.

  40. 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.

  41. More Information Read more about Forensic Toxicology from Court TV’s Crime Library at:

  42. Chapter 7Drugs “Having sniffed the dead man’s lips, I detected a slightly sour smell, and I came to the conclusion that he had poison forced upon him.” —Sherlock Holmes, in Sir Arthur Conan Doyle’s A Study in Scarlet

  43. Drugs and Crime • A drug is a natural or syntheticsubstance designed to affect the subject psychologically or physiologically.

  44. Drugs and Crime • “Controlled substances” are drugs that are restricted by law • Controlled Substances Act is a law that was enacted in 1970; it lists illegal drugs, their category and their penalty for possession, sale or use.

  45. Controlled Substances Act • Schedule I – high potential for abuse; no currently acceptable medical use in the U.S.; a lack of accepted safety for use under medical supervision

  46. Controlled Substances Act • Schedule II – high potential for abuse; a currently accepted medical use with severe restrictions; abuse may lead to severe psychological or physical dependence

  47. Controlled Substances Act • Schedule III – lower potential for abuse than the drugs in I or II; a currently accepted medical use in treatment in the U.S.; abuse may lead to moderate physical dependence or high psychological dependence

  48. Controlled Substances Act • Schedule IV – low potential for abuse relative to drugs in III; a currently accepted medical use in treatment in the U.S.; abuse may lead to limited physical dependence or psychological dependence relative to drugs in III

  49. Controlled Substances Act • Schedule V – low potential for abuse relative to drugs in IV; currently accepted medical use in treatment in the U.S.; abuse may lead to limited physical dependence or psychological dependence relative to drugs in IV

  50. Examples of Controlled Substances and Their Schedule Placement • Schedule I—heroin (diacetylmorphine), LSD, marijuana, ecstasy (MDMA) • Schedule II—cocaine, morphine, amphetamines (including methamphetamines), PCP, Ritalin