Stages of Intoxication Factors affecting alcohol absorption – Body weight – How much alcohol is consumed – Over what time period – Amount of food in the stomach – Frequency of drinking alcohol – Body fat percentage – Medications and popular energy drinks Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 1

Alcohol is attracted to water so it collects in body tissues that have higher amounts of water. People with more body fat will have a higher BAC than people with lower body fat, when both people consume the same amount of alcohol. – Body fat does not have water to attract the alcohol so more alcohol is left in the bloodstream, increasing blood alcohol levels. Food in the stomach slows alcohol absorption as well. Water or fruit juice will slow the absorption of the alcohol. Carbonated drinks speed up the absorption of alcohol. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 2

20 % of the alcohol is absorbed directly into the bloodstream through the walls of the stomach. 80% is absorbed through the small intestine Medications with a sedative effect will enhance the effect of the alcohol. Alcohol might interfere with or block the action of the medication, decreasing the medicine’s effectiveness. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 3

Stages of Intoxication Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 4

TOLERANCE A regular drinker may develop alcohol tolerance. Tolerance is the body’s need for progressively larger amounts of a chemical to cause the same levels of intoxication. There are two kinds of tolerance— – Metabolic tolerance—the body produces larger amounts of alcohol dehydrogenase – Functional tolerance—a person displays fewer visible symptoms of intoxication without affecting blood alcohol concentration Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 5

ALCOHOL AND THE LAW In most states, blood alcohol level > 0.08 is considered driving under the influence and is illegal. In the US, all states have implied consent laws concerning alcohol. – These laws prevent impaired motorists from refusing to submit to a breath test or blood test by invoking their Fifth Amendment rights. – According to implied consent, there is an agreement that you will not operate a motor vehicle if you are under the influence of alcohol. – Anyone who is suspected of driving while under the influence of alcohol may be requested to submit a breath or blood sample for analysis. – If the driver refuses, he or she will lose his or her driver’s license for a specified time. – In most states the length of time is six months to a year. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 6

Schmerber v. California – 1966, Anoncenda Schmerber sued police because a blood sample was taken and tested for alcohol without his consent. – Schmerber was being treated in the hospital emergency room for injuries he suffered in a traffic accident. – The results of the blood alcohol test indicated that he had been driving while intoxicated and he was arrested. – He argued that taking the sample of blood violated his Fifth Amendment right to refuse to testify against himself. – The case eventually reached the United States Supreme Court, which ruled that the Fifth Amendment privilege applied only to testimonial evidence, not to physical evidence such as fingerprints or blood samples. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 7

DETERMINING ALCOHOL LEVELS Blood alcohol has to be test quickly the alcohol will continue to metabolize in the suspect’s body. Urine may also be tested; however, urine is a less reliable indicator of blood alcohol level because the alcohol concentrates in the urine for 24 hours or more after the person has stopped drinking. Drivers pulled over for suspicion of DUI is subjected to sobriety tests. Because actual blood testing must be done in a laboratory, presumptive field tests are often performed to determine whether further testing is required. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 8

FIELD SOBRIETY TESTS 1 st clue that a driver has been drinking is the odor of alcohol. The cop may perform a horizontal gaze nystagmus (HGN) test.a horizontal gaze nystagmus (HGN) test. A human’s eyes make involuntary jerking motions, called nystagmus. Intoxication makes nystagmus more pronounced. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 9

To perform the HGN test: a small flashlight or penlight is held at eye level and moved slowly from side to side. The subject is asked to follow the movement of the light with his or her eyes, not moving the head. Police officers are trained to recognize the eye movements that are consistent with intoxication (see Figure 9-9). A driver’s inability to “pass” these tests is an indication that more tests should be completed Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 10

Divided-attention tests – Tests that require concentration on more than one task at a time. – Used to judge alcohol impairment. – Ex. A person counting or reciting the alphabet backwards. – If an additional task, such as standing on one foot, is added, the intoxicated person would have difficulty performing the tasks simultaneously. – The familiar “walk the straight line, heel to toe” test (see Figure 9-10) measures the person’s ability to concentrate on two tasks at the same time. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 11

Field Sobriety Tests BREATH TESTS Since alcohol is excreted through the urine, perspiration, and breath, there is a direct correlation between the amount of alcohol in the breath and the blood alcohol level. Alcohol in breath to blood ratio is 1:2100 (2,100 mL of exhaled air contains the same amount of alcohol as 1 mL of blood) A breath test, such as a breathalyzer, measures the amount of alcohol in exhaled air. Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 12

Blood and Urine Tests Toxicology labs use gas chromatography/ mass spectrometry (GC/MS) Gas chromatography separates the sample into individual components Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9 © 2012 Cengage Learning. All Rights Reserved 13