Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Forensic Toxicology • Definition: The science of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs. Controlled Substances Act • • Federal Law established 5 schedules of classification of controlled substances based on – Drug’s potential for abuse – Potential to physical and psychological dependence – Medical Value Note: Federal law also controls materials that are used in making drugs and those that are manufactured to resemble drugs Drug Schedules • • • • • Schedule I: • Drugs with high potential for abuse and addiction, NO medical value Ex: Heroin, LSD, Ecstasy, Marijuana Schedule II: • Drugs with high potential for abuse and addiction, have some medical value with restrictions Ex: PCP, Cocaine, Amphetamines, Most Opiates, Some Barbiturates Schedule III: • Drugs with less potential for abuse and addiction, currently acceptable for medical use Ex: Some Barbiturates, Codeine, Steroids Schedule IV: • Drugs with low potential for abuse and addiction, currently acceptable for medical use Ex: Tranquilizers like Valium, Xanax, Librium Schedule V: • Drugs with low potential abuse, medical use, lowest potential dependency Ex: Some Opiates with Non-Narcotic Ingredients Role of the Toxicologist • • • Must identify one of thousands of drugs and poisons Must find nanogram to microgram quantities dissipated throughout the entire body Not always looking for exact chemicals, but metabolites of desired chemicals (ex. heroin morphine within seconds) Toxicology Procedures • • • • • • 10mL of blood in airtight container – Add anticoagulant – Add preservative 2 consecutive urine samples – Some drugs take a while to show up in urine (1-3 days) Vitreous humor (liquid in eyeball) Hair samples Screening– quick test to narrow down possibilities – color tests, TLC (thin layer chromatography), immunoassay Confirmation– determines exact identity – GC/Mass Spec Color Tests • • • Marquis Test: – Turns purple in the presence of Heroin, morphine, opium – Turns orange-brown in presence of Amphetamines Scott Test: Three solutions – Blue then pink then back to blue in the presence of Cocaine Duquenois-Levine: – Test for marijuana –turns purple More Analytical Tests • • • Microcrystalline Tests: Identifies drug by using chemicals that reacts to produce characteristic crystals Chromatography: TLC, HPLC and gas – separate drugs/tentative ID Mass Spectrometry: chemical “fingerprint” no two drugs fragment the same Note: HPLC = high pressure liquid chromatography Why? • • Think of all the people that you have “heard” do drugs. US drug manufacturers produce enough barbiturates and tranquilizers each year to give every person in the US 40 pills • • (that’s about 12 billion pills) 18,000 out of 44,000 annual traffic deaths are alcohol related and send over 2 million people to the hospital Toxicology of Alcohol • • Alcohol is absorbed through the stomach and intestine Once absorbed, alcohol is: – Oxidized- in liver by alcohol dehydrogenase—turned into acidic acid – Excreted- by breath, perspiration, and kidneys—turned into carbon dioxide and water Factors that Affect Alcohol Absorption • • • Time of consumption Type of alcoholic beverage Presence of food in stomach Toxicology of Alcohol • Alcohol intoxication depends on – Amount of alcohol consumed – Time of consumption – Body weight – Rate of alcohol absorption Fate of Alcohol • Alcohol is absorbed into the bloodstream • Distributed through-out the body’s water • And finally eliminated by oxidation and excretion Note: A. Oxidation is the combination of oxygen and alcohol to produce new products by the liver B. Elimination is removing alcohol from the body in an unchanged state; normally excreted in breath and urine Alcohol in the Circulatory System • • Measuring the quantity of alcohol in the blood system determines the degree to which someone is drunk Two methods of making this measurement – Measurement of alcohol content in blood – Measurement of alcohol in breath Circulation Definitions • • • 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—walls exchange materials between blood and tissues • Alveoli—small sacs in lungs—exchange vapors between breath and blood Note: If alcohol is present, it will be passed from the blood into the alveoli where it will be passed on to the mouth and nose during the act of breathing. • Evidence has shown that the ratio of alcohol to alveoli air is approx. 2100 to 1—This is a basis for relating breath to blood-alcohol concentration. Analysis of BAC • • • Breath Tests Field Sobriety Tests Blood Tests Breath Tests • • • A breath test reflects the alcohol concentration in the pulmonary artery. One instrument used for breath tests is called The Breathalyzer. The Breathalyzer is a device for collecting and measuring the alcohol content of alveolar breath. The Breathalyzer • • • • • • The Breathalyzer traps 1/40 of 2100 mL of alveolar breath. Since the amount of alcohol in 2100 mL of breath approximates the amount of alcohol in 1 mL of blood— the Breathalyzer in essence measures the alcohol concentration present in 1/40 of a mL of blood. Once the alveolar breath is trapped it is allowed to undergo a chemical reaction: 2K2Cr2O7 + 3C2H5OH + 8H2SO4 2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O The Breathalyzer indirectly determines the quantity of alcohol consumed by measuring the absorption of light by potassium chromate before and after its reaction with alcohol, using the principle of spectrophotometry Other Breath Tests • • • Infrared breath-testing instrument Fuel cell Note: These instruments are used more recently because they don’t depend upon chemical reagents and are entirely automated. Infrared-Breath Test • • • Uses the principle that infrared light is absorbed when shined on alcohol Essentially, the infrared light passes through a chamber where it will interact with the alcohol and cause the light density to decrease. The decrease in light intensity is proportional to the concentration of alcohol present in the captured breath Field Sobriety Testing Methods • • • • Field sobriety testing consists of a series of psychophysical tests and a preliminary breath test (typically done with a handheld fuel cell tester) These tests are preliminary and nonevidential in nature—they only serve to establish probable cause requiring a more thorough breath or blood test. Horizontal Gaze Nystagmus • Involuntary eye jerk as eye moves horizontally Divided attention tasks • Walk and Turn • One-Leg Stand Parts of the brain affected by Alcohol • • Alcohol 1st affects the forebrain and moves backward Last affected is medulla oblongata Alcohol and the Law • • • • 1939-1964: intoxicated = 0.15% BAC 1965: intoxicated = 0.10% BAC 2003: intoxicated = 0.08% BAC At least we don’t live in France, Germany, Ireland, or Japan (0.05%) or especially Sweden (0.02%)!