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Chapter 6 FORENSIC TOXICOLOGY FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-1 Toxicology Toxicology— the study of the adverse effects of chemicals or physical agents on living organisms. Video Types: Environmental — air, water, soil Consumer — foods, cosmetics, drugs Medical, clinical, forensic 2 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-2 Toxicologists • Toxicologists detect and identify the presence of drugs and poisons in body fluids, tissues, and organs. • Toxicologists not only work in crime laboratories and medical examiners’ offices, but may also reach into hospital laboratories and health facilities to identify a drug overdose or monitor the intake of drugs. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-3 Mathieu Orfilia – Father of Tox • The father of toxicology was Mathieu Orfilia in the early 1800’s . • His work mainly centered around arsenic. • It was relatively easy to get because it was the rat poison of the day and was the favorite murder weapon among poor people. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-4 Intoxicant vs. Poison: • An intoxicant such as alcohol requires that a relatively large amount be added to be lethal. • A poison, like cyanide, requires a relatively small amount to be fatal. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-5 Forensic Toxicology found in Postmortem —medical examiner or coroner examines body after death Antemortem —doctors/scientists examine the living body before death Environment — scientists examine industrial, catastrophic, terrorist events 6 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-6 Environmental Example: Love Canal New York An example of where forensic toxicology impacts the population is the Love Canal Disaster. https://www.youtube.com/watch?v=Kjobz14i8kM FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-7 Toxicology Toxic substances may: *Be a cause of death *Contribute to death *Cause impairment *Explain behavior 8 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-8 Life Example: Carbon Monoxide: FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-9 Aspects of Toxicity • Dosage - how much • 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 10 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-10 Lethal Dose LD50 (Leathal Dose 50%) • refers to the dose of a substance that kills half the test population, usually within four hours. • Testing is usually done on animals that compare well to humans metabolism. • Expressed in milligrams of substance per kilogram of body weight (mg/kg) 11 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-11 Toxicity Classification LD50 (rat,oral) Correlation to Ingestion by 150-lb Adult Human Toxicity <1 mg/kg a taste to a drop extreme 1–50 mg/kg to a teaspoon high 50–500 mg/kg to an ounce moderate 500–5,000 mg/kg to a pint slight 5–15 g/kg to a quart practically nontoxic Over 15 g/kg more than 1 quart relatively harmless The smaller the LD50, the more toxic the substance! 12 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-12 Symptoms of Various Types of Poisoning Type of Poison 1. Caustic poison (lye) Characteristic burns around the lips and mouth of victim 2. Carbon monoxide Red or pink patches on the chest and thigh, unusually bright red lividity 3. Sulfuric acid Black vomit 4. Hydrochloric acid Greenish-brown vomit 5. Cyanide- Seizures, Burnt almond odor 6. Arsenic diarrhea, vomiting, blood in the urine, cramping muscles, stomach pain, and convulsions. 7. Methyl (wood) or isopropyl (rubbing) alcohol Nausea and vomiting, unconsciousness possibly blindness 13 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-13 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 14 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-14 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 • Alcohol appears in blood within minutes; 30–90 minutes for full absorption • Detoxification —about 90 percent in the liver 15 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-15 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 • About 5 percent is excreted unchanged in breath, perspiration, and urine 16 FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-16 Alcohol & Circulatory System • Humans have a closed circulatory system consisting of a heart, arteries, veins, and capillaries. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-17 Alcohol & Circulatory System • Alcohol is absorbed from the stomach and small intestines into the blood stream. • Alcohol is carried to the liver where the process of its destruction starts. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-18 Alcohol & Circulatory System • Blood, carrying alcohol, moves to the heart and is pumped to the lungs. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-19 Alcohol & Pulmonary System • In the lungs, carbon dioxide and alcohol leave the blood and oxygen enters the blood in the air sacs known as alveoli. • Then the carbon dioxide and alcohol are exhaled during breathing. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-20 Breath Testers • Breath testers that operate on the principle of infrared light absorption are becoming increasingly popular within the law enforcement community. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-21 Toxicology of Alcohol • Like any depressant, alcohol principally affects the central nervous system, particularly the brain. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-22 Alcohol Levels • After consumption, alcohol concentration slowly decreases back to zero. • Factors such as time taken to consume the drink, the alcohol content, the amount consumed, and food present in the stomach determine the rate at which alcohol is absorbed. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-23 Alcohol Levels • Elimination of alcohol throughout the body is accomplished through oxidation and excretion. • Oxidation is a chemical reaction that takes place almost entirely in the liver • Excretion of unchanged alcohol occurs in the breath, urine, and perspiration. • The extent to which an individual may be under the influence of alcohol is usually determined by either measuring the alcohol content in the blood system (BAC) or by measuring the alcohol content in the breath (breathalyzer). FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-24 Alcohol Levels • Experimental evidence has verified that the amount of alcohol exhaled in the breath is in direct proportion to the blood alcohol concentration (BAC). FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-25 Alcohol and Law • Between 1939 and 1964 a person having a blood-alcohol level in excess of 0.15 percent w/v was to be considered under the influence, which was lowered to 0.10 percent by 1965. • In 1972 the impairment level was recommended to be lowered again to 0.08% w/v. It remains there today. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-26 Alcohol and Law • To prevent a person’s refusal to take a test for alcohol consumption, the National Highway Traffic Safety Administration recommended an “implied consent” law. • Adopted by all states by 1973, this law states that the operation of a motor vehicle on a public highway automatically carries with it the stipulation that a driver will submit for a test for alcohol intoxication if requested or be subject to loss of the license. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-27 Breath Testers • Many types of breath testers are designed to analyze a set volume of breath. • The captured breath is exposed to infrared light. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-28 Breath Testers • It’s the degree of the interaction of the light with alcohol in the captured breath sample that allows the instrument to measure a blood alcohol concentration in breath. • Some breath testing devices also use fuel cells. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-29 Field Testing • Law enforcement officers typically use field sobriety tests to estimate a motorist’s degree of physical impairment by alcohol and whether or not an evidential test for alcohol is justified. • The horizontal gaze nystagmus test, walk and turn, and the one-leg stand are all considered reliable and effective psychophysical tests. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-30 Gas Chromatography Testing • Gas chromatography offers the toxicologist the most widely used approach for determining alcohol levels in blood. https://www.youtube.com/watch?v=4Xaa9WdXVTM FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-31 Gas Chromatography Testing • Blood must always be drawn under medically accepted conditions by a qualified individual. • It is important that a nonalcoholic disinfectant be applied before the suspect’s skin is penetrated with a sterile needle or lancet. • Once blood is removed from an individual, its preservation is best ensured when it is sealed in an airtight container after an anticoagulant and a preservative have been added and stored in a refrigerator. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-32 The Confirmation Step • The GC (gas chromatography) separates the sample into its components • The MS (mass spectrometer) breaks the sample into a unique “fingerprint” pattern that can be used for identification. https://www.youtube.com/watch?v=EzvQzImBuq8 • Once the drug is extracted and identified, the toxicologist may be required to provide an opinion on the drug’s effect on an individual’s natural performance or physical state. FORENSIC SCIENCE: An Introduction, 2nd ed. By Richard Saferstein ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 6-33