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Forensic Toxicology

Forensic Toxicology. Toxicology. Definition : Analysis of body fluids or tissues for the presence of 1) controlled substances, 2) common pharmaceuticals and 3) poisons. What do Toxicologists know? All about:

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Forensic Toxicology

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  1. Forensic Toxicology

  2. Toxicology • Definition: Analysis of body fluids or tissues for the presence of 1) controlled substances, 2) common pharmaceuticals and 3) poisons. • What do Toxicologists know? • All about: • drug interactions, metabolism, therapeutic vs. toxic doses, and impairment

  3. Challenges… • Identify 1 in 1000 drugs/poisons needle in a haystack • Find tiny (nanogram to microgram) quantities, through the entire body • Not always looking for exact chemicals …metabolitesare breakdown products Examples: heroin  morphine in seconds THC  THC-9 in urine

  4. Forensic Toxicology Father of Modern Toxicology… Orfila

  5. Paracelsus"All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” (1530 AD)

  6. Antemortem = before death DUIs BREATH Drug Facilitated Sex.Asslt. BREATH, URINE Workplace Drug Testing BREATH, URINE Parole violations BREATH Post mortem = after death Homicides Suicides Overdose MVA Unexplained death Natural (sometimes) Toxicology…when do we do it ??

  7. Toxicology of Alcohol • Alcohol is absorbed into the blood, via stomach and small intestine • Once absorbed, alcohol is: • Oxidized (oxidation = burned, with O2) in liver • Excreted in breath and urine… AS UNCHANGED PURE ALCOHOL !!

  8. Alcohol in the Circulatory System • Quantity of alcohol in the blood is… …how drunk you are. • Two methods of making this measurement • Measure alcohol in blood • Measure alcohol in breath

  9. Circulation Con’t Ratio of blood alcohol to alveoli air is approximately 2100 to 1 • Means 2100 mL of Breath has the same alcohol as 1mL of Blood

  10. The Breathalyzer

  11. Breathalyzer Con’t • 3 types of breathalyzers • Measure alcohol in different ways • Chemical… alcohol  some other chemical • Fuel Cell… alcohol  electricity • Infrared (IR) alcohol  reflects IR back

  12. Infrared Breath Test uses infrared wavelengths to test for alcohol Fuel Cell Test converts fuel (alcohol) and oxygen into a measurable electric current Infrared and Fuel Cell Breath Tests

  13. Field Sobriety Testing • Two reasons for the field sobriety test: • Assess suspects’ physical impairment • Determine need of evidential (urine) test.

  14. Field Sobriety Tests • Horizontal Gaze Nystagmus • Involuntary eye jerk as eye moves horizontally • Walk and Turn (divided attention tasks) • One-Leg Stand

  15. Horizontal Gase Nystagmus - CLIP http://www.bing.com/videos/search?q=horizontal+gaze+nystagmus+video&view=detail&mid=95C10FAF1ABA03518D1A95C10FAF1ABA03518D1A&first=0&qpvt=horizontal+gaze+nystagmus+video&adlt=strict

  16. At least we don’t live in France, Germany, Ireland, or Japan (0.05%) or especially Sweden (0.02%)! Alcohol and the Law • 1939-1964: intoxicated = 0.15% BAC • 1965: intoxicated = 0.10% BAC • 2003: intoxicated = 0.08% BAC

  17. Drug Testing in the Body • Urine is most common • Immunoassay • Based on antigen-antibody binding specificity • Antibody produced by injecting antigen (drug) into rabbit • Antibodies will bind to drug in urine • Confirmation done w/TLC

  18. False positives in Immunoassays • Poppy seeds and Vicks 44 for opiates • Decongestants for amphetamines • Benadryl and numerous cough syrups for PCP

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