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Toxicology and BAC Calculations

Toxicology and BAC Calculations. Think. What is one of the most commonly abused drug in America?. Alcohol and Driving - BAC. At a Blood Alcohol Concentration (BAC) of 0.08%, a person is 4 times more likely to be involved in an accident

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Toxicology and BAC Calculations

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  1. Toxicology and BAC Calculations

  2. Think • What is one of the most commonly abused drug in America?

  3. Alcohol and Driving - BAC • At a Blood Alcohol Concentration (BAC) of 0.08%, a person is 4 times more likely to be involved in an accident • Blood test for BAC – does this violate Fifth Amendment rights? • Schmerber vs. California • decided that 5th amendment only applies to testimonial evidence (cant testify against yourself) • Confounding Circumstances: • Arterial BAC greater than Venous BAC while alcohol is still being absorbed (can give false negative) • Why?

  4. Rate of Absorption of Alcohol • Dependent upon: • Quantity of alcohol consumed • Time over which alcohol was consumed • Form of alcohol • Contents of stomach • The more alcohol consumed, the faster it gets absorbed, the faster it is consumed, the faster it enters the blood • Although alcohol gets absorbed by the small intestine, it is possible for absorption to occur in the stomach

  5. Rate of Elimination • The body eliminates alcohol by excretion (breathing, sweating, urination) and oxidation (in liver  turned into CO2 and H2O) • RoE = 0.01 + 0.014(weight/300 lb) • Calculate your rate of elimination. • What is the determining factor? What does it mean? • Does a glass of wine have less alcohol than a can of beer?

  6. A Drink Is A Drink • Beer: 10-12oz at 4-5% • EQUALS • Wine cooler: 8-12oz at 4-6% • EQUALS • Table wine: 4-5oz at 9-12% • EQUALS • Fortified wine: 2.5oz at 20% • EQUALS • 80 proof Spirits: 1.25oz at 40% • EQUALS • 100 proof Spirits: 1 oz at 50% A drink is defined as having 1/2oz of pure ethyl alcohol Ounce (oz) at % (of alcohol) after ONE HOUR of drinking Proof / 2 = % ETOH

  7. Calculating BAC • % BAC (g/100mL) = 0.10 x MA/(VD x MB) • MA = mass of alcohol (g) • VD = volume of distribution (L/kg) (Men: 0.7L/kg; Women: 0.6L/kg) • MB = body mass (kg) (body weight in pounds/2.2) • MA for liquor (proofs) • MA = ounces of liquor x proof/200 x 28.4g/oz x 0.80g/mL • OR • = 0.11 x ounces of liquor x proof • MA for wine/beer • MA = ounces of liquor x percent/100 x 28.4g/oz x 0.80g/mL • OR • = 0.23 x ounces of liquor x percent • Question 4 and 5: TWO CASES

  8. Calculate your BAC and RoE • After drinking 2 shots of 151 Rum, what is your BAC? • Is it over the legal limit (0.08%, over 21; 0.02-0.07% under 21)? • If so, how long will it take to sober up? (use RoE from before) • RoE = 0.01 + 0.014(weight/300 lb)

  9. DWI – Two Steps • Field evaluation of suspected Drunk Driver • Erratic behavior of vehicle • Stopped at a checkpoint • Requires probable cause • Field sobriety test (NHTSA recommends 3) • Horizontal Gaze Nystagmus (HGN)** most reliable (involuntary) • Walk-and-Turn (WAT) • One-leg stand (OLS) • Act of Driving gives “implied consent” (NOT STANDARD PROCEDURE) • Breathalyzer, Intoxilyzer (IR), Electrochemical Instruments (used to calculate BAC) • Blood is 2100x concentration of breath (controlled by body temp – same for everyone) • Newest breathalyzers combine IR with fuel cell technology • A second Breathalyzer test will be done at the police station. Why?

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