Chapter 9 Physiology of Alcohol and Poisons © 2012 Cengage Learning. All Rights Reserved.

Chapter 9

Physiology of Alcohol and Poisons

© 2012 Cengage Learning. All Rights Reserved

2 Forensic Science II: Physiology of Alcohol and Poisons, Chapter 9


Introduction—Objectives

1. Describe the role of a forensic toxicologist.2. Discuss the legal importance of blood alcohol

levels.3. Explain the effects of alcohol and specific drugs

and poisons on the body.4. Discuss chemical agents that may be used for

bioterrorism.5. Describe analytical techniques for detection and

identification of alcohol, poisons, and toxins in bodily fluids.



Introduction—Vocabulary

o depressant—a chemical that slows the heart rate and brain activity and causes drowsiness

o Immunoassay—a test that relies on the antigen-antibody response

o Nystagmus—involuntary jerking movement of the eyes

o Poison—a chemical that can harm the body if ingested, absorbed, or breathed in sufficiently high concentrations



Introduction—Vocabulary

o Tolerance—in response to prolonged, heavy intake of alcohol or other drugs, the body’s need for progressively larger amounts of a chemical to cause the same levels of intoxication

o Toxin—a type of poison produced naturally by living things


© 2012 Cengage Learning. All Rights Reserved5

Michael Jackson

o June 25, 2009, an accidental homicideo Homicide—a person died at the hands of

another persono An overdose of medicines prescribed by

Jackson’s doctor, Conrad Murrayo Coroner’s determination—the interaction of

anesthetics and sedatives caused Jackson to stop breathing.



History (Obj 9.1)

o Early 1700’s—first use of chemistry to detect poisonso Early 19th century—toxicology became a new

scientific disciplineo France in 1840—Charles Lafarge trial involved

testing for arsenico Forensic toxicologists—study the legal and medical

aspects of alcohol, drugs, poisons, and toxins in bodily fluids.



Alcohol (Obj 9.2, 9.3)

o In everyday speech, alcohol usually refers to the ethanol used in alcoholic beverages.

o In chemistry, alcohols are a group of substances with a hydroxyl group.



Alcohol

o All alcohols are toxic in sufficient quantitieso As little as 30 mL of methanol can killo Ethanol, ethyl alcohol, is a colorless liquid

obtained from fermented grains or fruitso Initial reaction to alcohol is euphoriao Alcohol is actually a depressant



Alcohol in the Body

o Alcohol diffuses through the stomach and small intestines

o As alcohol concentration increases:• ability to respond to stimuli decreases• temporary euphoria results from depressing

inhibitions• lose coordination and become confused• memory diminishes



Alcohol in the Body

o The liver metabolizes alcohol with an enzyme called alcohol dehydrogenase (ADH)

o Resulting product is acetaldehydeo More enzymes break this into CO2 and H2Oo The body can metabolize 15 to 30 mL of

alcohol per houro Excess alcohol is distributed to body tissues



Stages of Intoxication

A blood alcohol concentration of 0.08 means

8 g of alcohol per 10,000 mL of blood




o Alcohol affects different people differently

Concentration Behavior0.01 to 0.05 Normal behavior

0.03 to 0.12 Euphoria begins

0.09 to 0.25 Vision blurs, loss of balance, sleepiness

0.18 to 0.30 Speech slurs, dizzy, disoriented, emotional



Stages of Intoxication (cont.)

o Alcohol affects different people differently

Concentration Behavior0.25 to 0.40 Standing and walking is difficult

0.35 to 0.50 Impaired respiratory and circulatory systems

Over 0.45 Potentially fatal




o 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



Tolerance

o Metabolic tolerance—the body produces larger amounts of alcohol dehydrogenase

o Functional tolerance—a person displays fewer visible symptoms of intoxication without affecting blood alcohol concentration



Field Sobriety Tests

o Horizontal gaze nystagmus (HGN) test • Nystagmus is the involuntary jerking of human

eyes, which increases with intoxicationo Divided-attention testso Breath tests

• Direct correlation between alcohol in the breath and alcohol in the blood stream

• Ratio is 1:2100



Blood and Urine Tests

o Toxicology labs use gas chromatography/ mass spectrometry (GC/MS)

o Gas chromatography separates the sample into individual components



Poisons (Obj 9.3, 9.4)

o Eaten (ingested)• 90% - at home, involving

children• household cleaners

o Inhaled• carbon monoxide• sarin, a nerve gas

o Injected• heroin

o Absorbed• Poison sumac, mustard

gas, ricin, anthrax



Drugs



Toxicological Testing (Obj 9.5)

o Detect trace amounts of drugs in the blood, urine, and body tissues with• thin layer chromatography,• gas chromatography, and• immunoassay techniques

o Confirmation is achievedusing GC/MS.



Toxicological Testing

o Reinsch test—for heavy metal poisoning• Certain metals dipped in hydrochloric acid

produce a silver-colored coating on coppero Emission spectroscopy or atomic absorption

spectrophotometry—identifies the specific metal

o Blood gas screenings—detects level of CO in the blood stream



Toxicological Testing

o Immunoassay—measures the level of antibodies produced in response to antigens (poisons) entering the bloodstream

o EMIT—enzyme-multiplied immunoassay technique• Rapidly detects several drugs and their

metabolites



Chapter Summary

o Poisons are chemicals that harm the body if ingested, inhaled, or absorbed through the skin.

o Forensic toxicologists investigate the legal and medical aspects of alcohol, drugs, poisons, and toxins in the body; also • testifying as expert witnesses, • collaborating with the medical examiner, and• analyzing evidence.



Chapter Summary

o The role of forensic toxicologist also includes:• testing employees for drug use, • screening athletes for drug use, and • testing sexual assault victims for the presence of

date rape drugs.o In everyday speech, alcohol usually refers to

the ethanol used in alcoholic beverages. o In chemistry, alcohols are a group of

substances with a hydroxyl group.



Chapter Summary

o Alcohol is a depressant. • Initially, it causes feelings of euphoria.• When more is consumed,

• motor skills become impaired, • brain function is depressed, and • the person may even lapse into a coma and die.

o The liver can metabolize about 15 to 30 mL of alcohol per hour. A person becomes intoxicated when consumption exceeds that.



Chapter Summary

o When a driver is suspected of intoxication, several field sobriety tests are given

o Presumptive tests • horizontal gaze nystagmus and • divided-attention tests

o Conclusive test• breath tests can determine blood alcohol levels.



Chapter Summary

o How the poison enters the body determines its effect on the body

• inhaled poisons can cause asphyxia• ingested poisons often target specific organs

o Testing procedures• Chromatography techniques, mass spectrometry, and

immunoassay are used to detect various poisons and drugs in urine and blood

• Reinsch test detects heavy-metal poisoning

Chapter 9 Physiology of Alcohol and Poisons © 2012 Cengage Learning. All Rights Reserved.

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Transcript of Chapter 9 Physiology of Alcohol and Poisons © 2012 Cengage Learning. All Rights Reserved.