Toxicology: Poisons and Alcohol

1. Toxicology: Poisons and Alcohol

2. Lesson Essential Questions: • What is toxicology? • How is toxicology important in forensic science? • What are the ways that scientists measure drugs, alcohol, and poisons? Kendall/Hunt Publishing Company

3. Toxicology Toxicology—the study of the adverse effects of chemicals or physical agents on living organisms Types: Environmental—air, water, soil Consumer—foods, cosmetics, drugs Medical, clinical, forensic Kendall/Hunt Publishing Company

4. 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

5. Toxicology Toxic substances may: Be a cause of death Contribute to death Cause impairment Explain behavior Kendall/Hunt Publishing Company

6. 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

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 Kendall/Hunt Publishing Company

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

9. 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 • The time period of exposure • The presence of other chemicals in the body or in the dose Kendall/Hunt Publishing Company

10. Lethal Dose LD50refers 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 Kendall/Hunt Publishing Company

11. Toxicity Classification Kendall/Hunt Publishing Company

12. Symptoms of Various Types of Poisoning Type of Poison Caustic poison (lye) Carbon monoxide Sulfuric acid Hydrochloric acid Nitric acid Phosphorus Cyanide Arsenic, mercury Methyl (wood) or isopropyl (rubbing) alcohol Symptom/Evidence Characteristic burns around the lips and mouth of victim Red or pink patches on the chest and thigh, unusually bright red lividity Black vomit Greenish-brown vomit Yellow vomit Coffee-brown vomit, onion or garlic odor Burnt almond odor Extreme diarrhea Nausea and vomiting, unconsciousness possibly blindness Kendall/Hunt Publishing Company

13. 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 Information —John Trestrail from Criminal Poisoning Kendall/Hunt Publishing Company

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

15. 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

16. 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

17. Alcohol—Ethyl Alcohol (C2H5OH) Most abused drug in America About 40 percent 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 percent in the liver About 5 percent is excreted unchanged in breath, perspiration, and urine Kendall/Hunt Publishing Company

18. 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 Kendall/Hunt Publishing Company

19. BAC: Blood Alcohol Content Expressed as percent weight per volume of blood Legal limit in all states is 0.08 percent Parameters influencing BAC: • Body weight • Alcohol content • Number of beverages consumed • Time since consumption Kendall/Hunt Publishing Company

20. BAC Calculation Burn-off rate of 0.015 percent per hour, but can vary: Male BAC = Female BAC = 0.071  (oz)  (% alcohol) body weight 0.085  (oz)  (% alcohol) body weight Kendall/Hunt Publishing Company

21. 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. This ratio of alcohol in the blood to alcohol in the alveolar air is approximately 2,100 to 1. In other words, 1 ml of blood will contain nearly the same amount of alcohol as 2,100 ml of breath. Kendall/Hunt Publishing Company

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

23. The Breathalyzer • More practical in the field • Collects and measures alcohol content of alveolar breath • Breath sample mixes with 3 ml of 0.025 percent K2Cr2O7 in sulfuric acid and water: 2K2Cr2O7 +3C2H5OH + 8H2SO42Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O • 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

24. Generalizations • During absorption, the concentration of alcohol in arterial blood is higher than in venous blood. • Breath tests reflect alcohol concentration in the pulmonary artery. • The breathalyzer also can react with acetone (as found in 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 readout. Prints out a card for a permanent record. Kendall/Hunt Publishing Company

25. More Information Read more about forensic toxicology at truTV’s Crime Library: http://www.crimelibrary.com/criminal_mind/forensics/toxicology/2.html Kendall/Hunt Publishing Company