Alcohol Toxicology Chapter 9

What is Alcohol??? Definition – a family of closely related chemicals whose molecules are made of carbon, hydrogen and oxygen Examples – methyl alcohol (methanol), isopropyl alcohol (isopropanol), butyl alcohol and ethyl alcohol (ethanol)*

Ethanol is the type of alcohol contained in popular beverages Chemical Formula for Ethanol: C2H5OH: H H H C C OH H H

IS Alcohol… A food? YES A drug? A poison? It all depends on the dose! Ethanol’s LD 50 in rats is 13.7 g/kg of body weight LD 50 = dose that is lethal for 50% of population

Toxicology of Alcohol Alcohol is absorbed through the stomach and intestine Once absorbed, alcohol is: Oxidized- in liver by alcohol dehydrogenase—turned into acetic acid Excreted- by breath, perspiration, and kidneys—turned into carbon dioxide and water

Alcohol Absorption 20% is absorbed through the stomach 80% diffuses into the blood through the walls of the small intestine Now the alcohol can be distributed to other body parts

Parts of the brain affected by Alcohol Alcohol 1st affects the forebrain and moves backward Last affected is medulla oblongata

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

Example: an Irish Whiskey that is 100 proof CALCULATING ALCOHOL CONTENT OF BEVERAGES Proof is actually double the alcohol content Example: an Irish Whiskey that is 100 proof has a 50% ethanol content

Size Can be Deceiving!! Beer – 12 oz. can @ 4% alcohol (8 proof) is equivalent to 0.48 ounces of pure ethanol Wine – 4 ounce glass @ 12% alcohol (24 proof) is equivalent to 0.48 ounces of pure ethanol Whiskey – 1 shot , 1.25 ounces @ 40% alcohol (80 proof) is equivalent to 0.5 ounces of pure ethanol

= = SO… Ingestion of any of the above results in equal 1 ¼ oz. whiskey 12 oz. beer 4 oz. wine Ingestion of any of the above results in equal amounts of ethanol entering the system

Fate of Alcohol Alcohol is absorbed into the bloodstream Distributed through-out the body’s water And finally eliminated by oxidation and excretion

Oxidation of Alcohol in the Liver The Liver Burns Ethanol – chemically combines it with oxygen The process is aided by the enzyme alcohol dehydrogenase 95%-98% is oxidized to CO2 and H2O in the liver

Oxidation of Alcohol in the Liver Acetyl aldehyde Alcohol CO2 + H2O + Energy Due to metabolism, the average person’s BAC drops about 0.015% per hour

Fate of Alcohol Con’t Note: Oxidation is the combination of oxygen and alcohol to produce new products by the liver 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 and Alcohol

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

Circulation Con’t 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 Con’t The Breathalyzer traps 1/40 of 2100 milliliters of alveolar breath. Since the amount of alcohol in 2100 milliliters of breath approximates the amount of alcohol in 1 milliliter of blood—the Breathalyzer in essence measures the alcohol concentration present in 1/40 of a milliliter of blood.

Breathalyzer Con’t 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 Potassium dichromate Ethyl alcohol Sulfuric acid Chromium sulfate Potassium sulfate Acetic acid Dihydrogen oxide

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

Fuel Cell—Breath Test A fuel cell converts a fuel and an oxidant into an electrical current. In this test, the breath alcohol is the fuel and atmospheric oxygen acts as the oxidant. Alcohol is converted, generating a current that is proportional to the quantity of alcohol present in the breath.

Infrared and Fuel Cell Breath Tests Infrared Breath Test uses infrared wavelengths to test for alcohol or other interferences in the breath Fuel Cell Test converts fuel (alcohol) and oxygen into a measurable electric current

Field Sobriety Testing Two reasons for the field sobriety test: Used as a preliminary test to ascertain the degree of the suspect’s physical impairment To see whether or not an evidential test is justified.

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.

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

Alcohol and the Law 1939-1964: intoxicated = 0.15% BAC 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

Alcohol and the Law Try the drink wheel: http://www.intox.com/wheel/drinkwheel.asp

Schmerber v. California 1966 Fifth Amendment Violation? The Fifth Amendment protects against self incrimination Fourth Amendment Violation? The Fourth Amendment protects against unlawful search and seizure

The End