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Forensic Toxicology

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  1. Forensic Toxicology Analytical Toxicology Fall 2007

  2. Forensic Toxicology • Toxicology is defined as the study of the adverse effects of chemicals on living organisms. • Forensic toxicology is defined as the application of toxicology for the purposes of the law.

  3. Forensic Toxicology • Postmortem forensic toxicology. • Human performance toxicology. • Forensic drug testing.

  4. History • Ancient Egyptians and Grecians reported poisonings due to herbs, plants and food. • Opium, arsenic and hydrocyanic acid were used throughout Europe during the middle ages.

  5. History • Philippus Theophrastus Aureolus Bombastus von Hohenheim (or Paracelsus) observed that any substance could be a poison, depending on its dose • “ What is there that is not poison? All things are poison and nothing without poison. Solely the dose determines that a thing is not a poison”

  6. History • In 1814, M.J.B. Orfila, the chairman of the legal medicine department at the Sorbonne in France, published a book entitled Traite des poisons ou Toxicologie Generale.

  7. History • In 1851, Stas developed the first effective method for extracting alkaloids from biological specimens. • This was modified several years later by Otto, which enabled the isolation of purer alkaloid substances.

  8. History • In the U.S., forensic toxicology did not develop until the early 20th century. • Dr. Alexander Gettler is considered this country’s first forensic toxicologist.

  9. Postmortem Forensic Toxicology • Suspected drug intoxication cases • Homicides • Arson fire deaths • Motor vehicle fatalities • Deaths due to natural causes

  10. Postmortem Forensic Toxicology • Death Investigations • Coroner • Medical Examiner

  11. Postmortem Forensic Toxicology • Specimens • Blood – from the heart and from the femoral or jugular veins • Vitreous humor • Urine • Bile • Liver • Other – lung, spleen, stomach contents or brain

  12. Postmortem Forensic Toxicology • Analytical Process • Separation • Identification • Confirmation • Quantitation

  13. Postmortem Forensic Toxicology • Analytes • Volatiles (Carbon Monoxide, Cyanide, and Alcohols) • Drugs • Metals

  14. EHTANOL (1.787 min.) 2-PROPANOL (2.804 min.) ACETALDEHYDE (1.414 min.) ACETONE (2.462 min.) MEK(ISTD) (5.584 min.) 0 6

  15. Postmortem Forensic Toxicology • Drugs • One Comprehensive Approach:

  16. Postmortem Forensic Toxicology • Metals • Aluminum • Arsenic • Iron • Mercury • Lead • Thallium

  17. Postmortem Forensic Toxicology • Metals (continued) • Analysis • Colorimetric • Graphite Furnace Atomic Absorption Spectrometry • Inductively Coupled Plasma – Mass Spectrometry • Neutron Activation Spectrometry

  18. Human Performance Toxicology • Human performance toxicology is also referred to as behavioral toxicology. • It is the study of human performance under the influence of drugs.

  19. Human Performance Toxicology • Ethanol and driving • History • Behavioral effects • Specimens

  20. Ethanol Toxicology • Types of alcohol • Ethanol (ethyl alcohol) • Methanol (methyl alcohol) • Isopropanol • Ethylene glycol

  21. Ethanol Toxicology • Ethanol production • Fermentation of sugar or starch • Can only achieve 20% ethanol • Distillation • Distilled alcoholic beverages are usually 40 to 50% ethanol by volume (80-100 proof)

  22. Ethanol Pharmacokinetics • Absorption • Means of absorption • Dermal • Inhalation • IV • Oral • Gastrointestinal tract • Presence of food.

  23. Ethanol Pharmacokinetics • Distribution • Gastrointestinal tract • Portal vein • Liver • Heart • Lung • Heart • Body

  24. Ethanol Pharmacokinetics • Elimination • 5-10% in the urine • Saliva, expired air and sweat • Liver (enzymatic oxidation to acetaldehyde, acetic acid and carbon dioxide)

  25. Ethanol Effects on the Body • Cardiovascular system • Central nervous system • Gastrointestinal tract

  26. Ethanol Effects on the Body • Kidney • Liver

  27. Breath Ethanol Testing • Theory • Henry’s law • Ethanol in breath Vs ethanol in blood • 2100 to 1 ratio • 2300 to 1 ratio

  28. Breath Ethanol Testing • Types of analyzers • Chemical • Reaction of ethanol with potassium dichromate/sulfuric acid solution • Colored solution that results is measured spectrophotometrically • IR spectrophotometry • Electrochemical oxidation - fuel cell

  29. Breath Ethanol Testing • IR Spectrophotometry • Based on absorbance of light by the ethanol molecule • Mainstay in evidential breath testing devices • Electrochemical Oxidation • Oxidation of ethanol to acetic acid • Also used in evidential breath testing

  30. Blood Ethanol Testing • Chemical • Screening • Quantitative • Disadvantage - aldehydes and ketones will interfere with the test

  31. Blood Ethanol Testing • Enzymatic • Conversion of NAD to NADH by ethanol (serum, urine and whole blood) • Measured spectrophotometrically at 340 nm • Same reaction with a blue dye (thiazoyl blue) (serum, urine, fresh blood and postmortem blood) • Measured with a fluorometer

  32. EHTANOL (1.787 min.) 2-PROPANOL (2.804 min.) ACETALDEHYDE (1.414 min.) ACETONE (2.462 min.) MEK(ISTD) (5.584 min.) 0 6 Blood Ethanol Testing • Gas Chromatography • Can measure ethanol in a wide range of specimens • Can distinguish ethanol from other alcohols, aldehydes and ketones • Two common methods • Head space • Direct injection

  33. Assessment of Ethanol Impairment • In a British study: • Detectable deterioration of drivers at between 30 – 50 mg/dL • Obvious deterioration observed at between 60 – 100 mg/dL • In another British study: • Pilots exhibited impairment at 40 mg/dL

  34. Assessment of Ethanol Impairment • Blood alcohol concentration: • 10-50 mg/dL: Impairment detectable by special tests • 30-120 mg/dL: Beginning of sensory-motor impairment • 90-250 mg/dL: Sensory-motor incoordination; impaired balance • 180-400 mg/dL: Increased muscular incoordination; apathy; lethargy

  35. Assessment of Ethanol Impairment • Blood alcohol concentration: • 250-400 mg/dL: Impaired consciousness; sleep; stupor • 350-500 mg/dL: Complete unconsciousness; coma • 450 and greater mg/dL: Death from respiratory arrest

  36. Human Performance Toxicology • Drugs and driving • DEC program • Drug recognition expert • Toxicologist • Prosecution

  37. Human Performance Toxicology • Drug Recognition Evaluation - 12 Step Process • Breath alcohol test • Interview of the arresting officer. • Preliminary examination of the suspect. • Examination of the eyes. • Divided attention psychophysical tests. • Vital signs examination.

  38. Human Performance Toxicology • Drug Recognition Evaluation (continued) • Dark room examination. • Examination of muscle tone. • Examination for injection sites. • Suspect’s statements and other observations. • Opinion of the evaluator. • Toxicological examination.

  39. Human Performance Toxicology • Drug Recognition Evaluation

  40. Human Performance Toxicology Drug Recognition Evaluation

  41. Human Performance Toxicology • Drug Recognition Evaluation (continued) • Toxicology • Type of Testing • Specimens

  42. Human Performance Toxicology • Drug Recognition Evaluation (continued) • Drug Class Effects • Central Nervous System Depressants • Central Nervous System Stimulants • Hallucinogens • Phencyclidine • Narcotic Analgesics • Inhalants • Cannabis

  43. Forensic Drug Testing • Introduction • History • Military • Criminal justice system • Public sector • Private sector • Rationale

  44. Forensic Drug Testing • Uses in the workplace: • Pre-employment screening • Post-accident testing • Return to Work testing • “For Cause” testing • Random testing

  45. Forensic Drug Testing Military Experience

  46. Forensic Drug Testing President Ronald Reagan 1986 Executive Order No. 12564 Objective: To develop a “drug-free” workplace.

  47. Forensic Drug Testing Mandatory Guidelines for Federal Workplace Drug Testing Programs

  48. Forensic Drug Testing Mandatory Guidelines Laboratory Accreditation Specified Menu & Cutoffs Proficiency Testing Inspections External Blind Controls Corrective Actions