Ch 10   Forensic Toxicology

Ch 10 Forensic Toxicology PowerPoint PPT Presentation

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. . Blood alcohol in your state.Significance of the implied consent law and the Schmerber v. California case to trafic enforcement.Acids and bases.Role of toxicologist in the criminal justice system.Techniques of isolating and identifying drugs and poisons.Finding a drug in human tissues and organs..

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Ch 10 Forensic Toxicology

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1. Ch 10 – Forensic Toxicology Alcohol in the bloodstream. Human circulatory system. Alcohol excretion in the breath. Breath-analyzer. Chemical equations. Infrared breath-testing device. Field sobriety tests. Alcohol concentration in blood.

2. Blood alcohol in your state. Significance of the implied consent law and the Schmerber v. California case to trafic enforcement. Acids and bases. Role of toxicologist in the criminal justice system. Techniques of isolating and identifying drugs and poisons. Finding a drug in human tissues and organs.

3. Collaboration between Drug Recignition Expert and Forensic Toxicologist in positive drug finding.

4. Absorption: passage of alcohol across the wall of the stomach and small intestine into the blood stream  Oxidation: the combination of oxygen with other substances to produce new products  Excretion: elimination of alcohol from the body in an unchanged state; alcohol is normally excreted in breath and urine

5. Artery: a blood vessel that carries blood away from the heart Vein: a blood vessel that transports blood toward the heart Capillary: a tiny blood vessel across whose walls exchange of materials between the blood and the tissue takes place; receives blood from arteries and carries it to veins

6. Alveoli: small sacs in the lungs through whose walls air and other between the breath the breath and the blood Catalyst: a substance that acceleration the rate of a chemical reaction but is not itself permanently changed by the reaction Fuel cell: a detector in which chemical reactions are used to produce electricit

7. Anticoagulant: a substance that prevents coagulation or clotting of the blood Preservative: a substance that stops the growth of microorganisms in blood Metabolize: transforming a chemical in the body to another chemical for the purpose of facilitating its elimination from the body Acid: a compound capable of donating a hydrogen ion (H+) to another compound

8. Base: a compound capable of accepting a hydrogen ion (H+) pH: a symbol used to express the basicity or acidity of a substance. A pH of 7 is neutral; lower values are acidic and higher values are basic

9. Ch. 10 - Forensic Toxicology Alcohol

10. What is Toxicology? Toxicological examinations involve the identification and often quantitation of drugs & toxic materials in the human body The role of the forensic toxicologist is limited to matters pertaining to violations of criminal law

11. Paracelsus “What is there that is not a poison? All things are poison and nothing without poison. Solely the dose determines that a thing is not a poison.”

12. What is Forensic Toxicology? Toxicology: Study of drugs and poisons and their adverse affects on the human system. Subfields include: pharmacokinetics (how the drug works on people) pharmacodynamics (how people work on the drugs)

13. Toxic Substances LD50 Calculations: Cyanide (for 150 lb human - ~ 70 Kg) (70Kg)(10mg/Kg) = 700 mg (0.70g) Nicotine (e.g.; from Cigarettes) (70Kg)(2 mg/Kg) = 140 mg (0.14g) (note 1 cig. = ~ 2 mg Nicotine) Ethanol (70Kg)(1000mg/Kg) = 70,000mg (70g) Effect of Body Weight: Ethanol 150 lb Human = lethal dose = ~ 70 g 40 lb Dog = lethal dose = ~ 20 g

14. Forensic Toxicological Questions Intentional or Accidental Poisoning? What type of Poison? Corrosive Poisons - Substances that actually destroy tissue outright Metabolic Poisons - Affect biochemical mechanisms. Drug Use - what drug, how much and when? Activity while under the influence of drugs?

15. Common Terms Analyte - the compound that you’re analyzing for. Metabolite - Compound formed from the metabolism of a drug. Heroin quickly metabolizes to Morphine so Morphine is a metabolite of Heroin.

17. Specimen Collection Fluids: Organs: Blood Skin Urine Lungs Vitreous Humuor Hair and Fingernails Oral Fluid Liver Semen Kidney Stomach Contents Bone Bile Other (heart, brain…)

18. Sampling Blood - It matters where you sample in the body Blood taken near the liver or other solid organ may contain drug that has diffused from the organ into the blood post-mortem to give very high drug levels. Take blood from femoral artery because it’s far from organs. Urine - tends to concentrate compounds. Can’t be sure of body concentration since it is unknown how long it has been accumulating in the body. Liver - concentrates and stores drugs for long times. good for detection but problematic for concentrations.

19. Sampling Bile - Useful for detection but not concentration. Kidney - Similar to Bile. Vitreous Humuor - Correlates well with femoral blood for most compounds. Hair and Fingernails - Good for some compounds with timelines possible. Oral Fluids - Can be easily disguised. Others - May be good for certain analyses but not generally good sources for many compounds.

20. Additional Matrices Vomit Meconium Earwax Amniotic Fluid Semen Umbilical Cord Blood Feces Milk Sweat

21. Specimen Collection: Case Examples Deceased Suspected drug related death Road Traffic Death Murder Antecedent Drink/drug driving Drug Facilitated Sexual Assault (DFSA) Professional/amateur athlete Workplace drug testing

22. Roles of Forensic Toxicology Postmortem Forensic Toxicology Human Performance Toxicology Forensic Drug Testing

23. Postmortem Forensic Toxicology Death Investigation Medical Examiners Office. NYS - elected Coroners or appointed Medical Examiners depending upon county. Forensic Pathologist responsible for performing autopsy. Forensic Toxicologist responsible for analyzing biological samples for poisons.

24. Specimen Collection Essential to collect the appropriate specimens and that they are collected, packaged, transported, and stored correctly. Pathologist is responsible for the collection of the human-derived specimens and may consult the toxicologist on unusual cases.

25. Specimen Collection MOST IMPORTANT STEP!!!! Obtain a Representative Sample: ‘A small portion of a material taken from a bulk specimen and selected in such a way that it possesses the essential characteristics of the bulk’. [E.g., easily possible to pick out a few crystals from a sample that do not reflect the majority of the sample - maybe that’s why they crystallized]

26. Sample Handling Storage Avoid - loss (due to volatility). - contamination (e.g., insufficient seal). Prevent - chemical interactions (e.g., Na and oil). - Degradation (refrigerate biological samples).

27. Sample Preparation Homogenising - making the sample uniform: grind (mortar and pestle) blender dissolution (water, solvents, acids)

28. Postmortem Forensic Toxicology Blood Samples Usually the most important specimen Ideally 2 samples (25 mL each) Femoral/jugular (peripheral site) - far as possible from solid organs Heart blood Trunk blood

29. Postmortem Toxicology Vitreous humor samples - The clear, gel-like mass that fills the space between the lens and the retina. Should be collected at all PM’s Relatively stable matrix Anatomically isolated area Good correlation with blood Easily obtained

30. Postmortem Toxicology Urine samples: All available sample should be collected. Higher concentrations present than in other matrices, but not always. Rapid tests available (both qualitative [what] and quantitative [how much] tests). Not always available.

31. Postmorten Toxicology Digestive System

32. Postmortem Forensic Toxicology Bile samples Alternative if urine unavailable Accumulation of drugs All available bile should be collected Not an easy sample to analyze

33. Postmortem Forensic Toxicology Liver samples: Drug metabolism occurs in the liver. Drugs may be present in higher concentrations. Metabolite Analysis.

34. Postmortem Forensic Toxicology Other specimens: Lung (volatiles) Spleen (carbon monoxide) – blood unavailable Stomach Contents (drug overdose) Hair ( drug use history)

35. Human Performance Toxicology The effects of drugs on skills, acquisition, learning, and performance. Drugs may alter normal behavior by either enhancing or impairing performance. Stimulant drugs can enhance performance – short term but used regularly can impair performance.

36. Human Performance Toxicology Not only illicit drugs (e.g. heroin, cocaine, cannabis, etc… Prescription medication can impair performance especially at the start of the treatment E.g. antidepressants, muscle relaxants, etc.

37. Steroids

38. Human Performance Toxicology Blood is the best specimen for determining impairment through drugs. In contact with the central nervous system. Hair/urine/sweat – becoming popular but unlikely that a quantitative relationship will exist.

39. Human Performance Toxicology Alcohol and/or Drugs Involving Driving: In addition to collecting the correct samples, additional information is essential: Witness statements to the incident Assessment of impairment at the scene Field Sobriety tests Drug Recognition Evaluation

40. Forensic Drug Testing - Where? Workplace Drug Testing Armed forces Prisons Private and public companies Schools International Olympic Committee Athletes Police Investigations Arrestee Drug Facilitated Sexual Assault (DFSA)

41. Toxicology of Alcohol The Fate of Alcohol in the Body

42. Properties of Alcohol Alcohol is a general term for a family of organic compounds commonly encountered members include methanol, ethanol, isopropanol The term alcohol will be taken to mean ethanol (ethyl alcohol)

43. Chemical Properties of Ethanol A clear volatile liquid Burns easily oxidizes easily Slight, characteristic odor Is very soluble in water miscible in all proportions

44. Physiological Properties of Ethanol A central nervous system (CNS) depressant CNS is the bodily system which is most severely affected by alcohol The degree to which the CNS function is impaired is directly proportional to the concentration of alcohol in the blood

45. What Does the Body Do With Alcohol? When an alcoholic beverage is swallowed, it is diluted by stomach juices & quickly distributed throughout the body Alcohol does not require digestion before its absorption into the bloodstream some diffuses into bloodstream directly through the stomach wall remainder passes into the small intestine rapidly absorbed & circulated

46. Alcohol Absorption Alcohol is absorbed from all parts of the gastrointestinal tract largely by simple diffusion into the blood small intestine is the most efficient region for absorption because of its large surface area The rate of absorption varies according to the particular beverage & the state of the consumer’s stomach

47. Alcohol absorption Fasting individual 20-25% of a dose of alcohol is absorbed from the stomach 75-80% is absorbed from the small intestine peak blood alcohol concentrations occur in 0.5-2.0 hrs

48. Alcohol Absorption Non-fasting individuals presence of food in stomach (especially gatty foods) delays absorption peak alcohol concentrations 1.0-6.0 hrs Alcohol ingested with carbonated beverages ordinarily absorbed more rapidly than straight alcohol

49. Alcohol Distribution Alcohol has a high affinity for water Is diffused in the body in proportion to the water content of the various tissues & organs greater concentration in blood & brain lesser concentration in fat & muscle

50. Alcohol Distribution Absorbed alcohol is greatly diluted by the aqueous body fluids 1 oz. (29.57 mL) of 50% (100 proof) whiskey will be diluted in a man of average build, to a concentration ~2 parts per 10,000 in the blood (0.02%)

51. Blood Alcohol concentration BAC is the amount of alcohol in the bloodstream measured in percentages BAC = 0.10% means a person has 1 part alcohol per 1,000 parts of blood in the body

52. Elimination Liver eliminate ~95% of the alcohol through metabolism oxidation via acetaldehyde & acetic acid to carbon dioxide & water Remainder of eliminated through excretion in breath, urine, sweat, feces, milk & saliva Rule of Thumb 0.5 oz (15 mL) alcohol eliminated per hr

53. Blood Alcohol Concentrations A set of probable average curves of BAC in an average-size man after rapid absorption of various amounts of alcohol Shows rate of BAC decline over time as a result of metabolism & excretion

54. Elimination Absorbed alcohol is passed through the liver by circulating blood ADH (alcohol dehydrogenase) converts the alcohol to acetaldehyde acetaldehyde is a highly toxic substance Aldehyde dehydrogenase converts acetaldehyde to acetate ion Acetate enters blood stream & is ultimately oxidized to CO2

55. Elimination Both enzymatic reactions require a co-enzyme, NAD, which accepts a hydrogen from the molecule The temporary depletion of NAD by the first step limits the rate at which alcohol can be metabolized

56. Curve a drinking 2 oz alcohol each hr for 4 hours BAC increase is cumulative because alcohol is consumed faster than it can be metabolized Curve b drinking 8 oz all at once

58. BAC’s Affect Behavior

59. Some Alcohol Statistics ~half of traffic injuries involve alcohol ~1/3 of fatally injured passengers & pedestrians have elevated blood alcohol levels ~half of homicides involve alcohol 1/2 to 1/3 of suicides involve alcohol CDC estimates ~30,000 unintentional injury deaths are directly attributable to alcohol

60. Alcohol & Driving

62. Respiratory System Volatile chemicals dissolved in the blood will be brought to equilibrium with the air in the lungs fixed ratio between compound in breath & blood

63. Alcohol in Blood vs Breath The ratio of alcohol in blood to alcohol in alveoli air is 2100 to 1 1 mL of blood will contain about the same amount of alcohol as 2100 mL of breath During the period of absorption, the alcohol concentration is higher in arterial blood than venous blood breath test reflects alcohol conc. in the pulmonary artery (reflects what reaches the brain

64. The Breathalyzer Measures the alcohol content of alveolar breath Subject blows into a mouthpiece until 52.5 mL of alveolar breath has been collected measures alcohol concentration of 1/40 mL of blood The alcohol in the blood is reacted with chromic acid

65. Breathalyzer Beers’ Law the concentration of Cr (VI) is directly proportional to the amount of 420 nm light light absorbed by the sample Measures the concentration of the unknown solution to the concentration of a standard sample

66. Legal Alternatives How other countries handle drunken drivers Australia – the driver is jailed and the name is sent to the local paper and published under the heading “He is drunk and in jail” Malaysia – the driver is jailed and, if married, his wife is also jailed Turkey – drunken drivers are taken 20 miles from town by the police and forced to walk back under escort Norway – three weeks in jail at hard labor, and one year loss of license (2nd offence w in five years and their license is revoked for life) Finland and Sweden – automatic jail for 1 year at hard labor Costa Rica – police remove plates from car Soviet Union – license revoked for life England – one year suspension, $250 fine, and jail for 1 year France – three years loss of license, one year in jail and $1000 fine Poland – Jail, fine, and mandatory political lectures Bulgaria – A second conviction results in execution El Salvador – your first offense is your last, execution by firing squad

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