Lecture 12: Toxicology

Question 1

What were the initial symptoms Bobby Curley experienced?

Answer 1

Burning/hurting feet, numbness, and difficulty walking.

Question 2

What was Bobby Curley diagnosed with at first?

Answer 2

Guillain Barr Syndrome.

Question 3

What caused Bobby Curley’s worsening condition despite initial improvement?

Answer 3

Thallium poisoning.

Question 4

How can thallium exposure occur?

Answer 4

Through inhalation, injection, or skin absorption.

Question 5

How was thallium traced back to Bobby Curley’s family?

Answer 5

Thallium was found in Bobby’s iced tea container at home.

Question 6

What is the role of forensic toxicologists?

Answer 6

Forensic toxicologists detect drugs and poisons in body fluids to identify overdoses and monitor drug intake

Question 7

Which drug is the most commonly abused legal drug in Western countries?

Answer 7

Alcohol is the most commonly abused legal drug in Western countries.

Question 8

What tragic events unfolded in Joanne and Bobby’s case?

Answer 8

Bobby ingested a lethal dose of thallium, Joanne poisoned him for financial gain, confessed to using rat poison, and even poisoned herself and her daughter to divert suspicion.

Question 9

Why is beer absorbed more slowly than 80 proof alcohol?

Answer 9

Beer’s carbohydrates slow absorption, leading to a lower peak alcohol level compared to 80 proof alcohol.

Question 10

How does alcohol distribute in the body once absorbed?

Answer 10

Alcohol becomes uniformly distributed in the watery parts of the body, constituting about 2/3 of the body’s volume.

Question 11

How does the body eliminate alcohol primarily?

Answer 11

Alcohol is primarily eliminated through oxidation in the liver by alcohol dehydrogenase, converting it to acetic acid, then CO2 and water.

Question 12

What is blood alcohol concentration defined as?

Answer 12

Blood alcohol concentration is the percentage weight per volume, e.g., 0.10% equals 0.10g per 100mL of blood.

Question 13

What is the legal limit for drunk driving in the United States?

Answer 13

The legal limit is a blood-alcohol concentration of 0.08%, equivalent to 0.08g alcohol per 100mL of blood or 80 mg/dL.

Question 14

How does alcohol primarily affect the human body?

Answer 14

Alcohol, as a depressant, mainly affects the central nervous system, especially the brain.

Question 15

What is the relationship between blood alcohol concentration and alcohol concentration in the brain?

Answer 15

Blood alcohol concentration correlates directly with alcohol concentration in the brain.

Question 16

What factors influence the absorption time of alcohol in the body?

Answer 16

Absorption time varies based on stomach fullness, type of beverage consumed, and ranges from 30 minutes to 4 hours.

Question 17

How does the type of beverage consumed affect alcohol absorption?

Answer 17

For example, beer is absorbed slower than 80 proof alcohol due to carbohydrates.

Question 18

What happens during the distribution phase of alcohol in the body?

Answer 18

Once absorbed, alcohol evenly spreads across the body’s watery compartments.

Question 19

How is alcohol absorbed into the bloodstream?

Answer 19

Alcohol is absorbed from the stomach and small intestines into the bloodstream.

Question 20

Which organ initiates the breakdown process of alcohol?

Answer 20

The liver initiates the process of alcohol breakdown.

Question 21

What is the key role of the lungs in the alcohol absorption process?

Answer 21

In the lungs, alcohol participates in an exchange with fresh air, leading to equilibrium in the blood in the alveoli sacs.

Question 22

What is the typical temperature of exhaled breath during the breath testing process?

Answer 22

The temperature of exhaled breath is typically 34°C.

Question 23

How do breath testers operate in detecting alcohol levels?

Answer 23

Breath testers use infrared light absorption, leveraging the known ratio of alcohol in blood to breath (approximately 2,100 to 1 at 34°C).

Question 24

How do breath testers measure blood alcohol concentration?

Answer 24

Breath testers use infrared radiation to analyze breath or fuel cells to convert alcohol to an electrical current for measurement.

Question 25

What happens to alcohol in breath samples during testing?

Answer 25

Alcohol in breath samples is oxidized, releasing electrons that generate a current for measurement.

Question 26

How does signal processing contribute to the accuracy of alcohol concentration measurement in breath testers?

Answer 26

Signal processing enables the direct display of alcohol concentration, ensuring accuracy, particularly at low alcohol levels.

Question 27

What types of field sobriety tests are used by law enforcement to assess physical impairment due to alcohol?

Answer 27

Tests like horizontal gaze nystagmus, walk and turn, and one-leg stand are common psychophysical tests used for assessment.

Question 28

Are portable breath testers with fuel-cell detectors admissible as proof in court for blood alcohol content?

Answer 28

Portable breath testers with fuel-cell detectors are used for preliminary testing but are generally not admissible as proof in court.

Question 29

What is the primary method used by toxicologists to determine alcohol levels in blood in forensic labs?

Answer 29

Gas chromatography is the primary method for alcohol level determination in forensic labs.

Question 30

How do hospital or clinical labs measure alcohol content in blood?

Answer 30

They use autoanalyzers to observe the conversion of alcohol to acetaldehyde through alcohol dehydrogenase.

Question 31

How are alcohol levels in blood typically determined?

Answer 31

Alcohol levels in blood are determined as serum alcohol levels.

Question 32

What steps are involved in the collection and preservation of blood for alcohol testing?

Answer 32

Blood collection must follow medical standards, use nonalcoholic disinfectants, add anticoagulants, seal in airtight containers, and store in refrigerators.

Question 33

What are ‘per se’ laws concerning blood alcohol concentration?

Answer 33

Per se laws set a defined blood alcohol concentration (often 0.08%) where individuals are considered intoxicated in all 50 states.

Question 34

What does the law mandate regarding alcohol intoxication tests for motor vehicle operators?

Answer 34

Operators must consent to the test when requested on public highways or face a license suspension.

Question 35

What types of substances do forensic toxicologists analyze, besides alcohol?

Answer 35

Forensic toxicologists analyze a variety of drugs and poisons, not limited to alcohol.

Question 36

How do toxicologists narrow down possibilities in the absence of supporting evidence?

Answer 36

Toxicologists use general screening methods to narrow down possibilities when supporting evidence is lacking.

Question 37

What is the two-step process in the analytical scheme for identifying abused drugs?

Answer 37

The two-step process involves screening and confirmation tests to identify abused drugs accurately.

Question 38

Why do positive results from screening tests require confirmation?

Answer 38

Positive results from screening tests are preliminary and need verification through confirmation tests for accuracy.

Question 39

What are some common screening tests used in drug screening methods?

Answer 39

Commonly used screening tests include thin-layer chromatography, gas chromatography, and immunoassays.

Question 40

Why is gas chromatography/mass spectrometry (GC/MS) preferred for confirmation testing?

Answer 40

GC separates sample components, while MS provides a unique fingerprint pattern for identification.

Question 41

In what sample sources are drug content typically tested for in living individuals?

Answer 41

Blood is commonly tested for drug content, while urine drug testing is increasingly common in workplace settings.

Question 42

How do blood concentration levels of drugs help toxicologists in assessments?

Answer 42

They help estimate pharmacological effects considering age, health, tolerance, and can provide insights into individual performance.

Question 43

How do drugs in hair serve as a historical marker for tracking drug intake?

Answer 43

Drugs in blood diffuse into hair, getting trapped in the hair’s protein structure. The location of drugs on the hair shaft tracks drug intake over time.

Question 44

How does the growth rate of human head hair aid in forensic analysis?

Answer 44

Human head hair grows at 1 cm per month, allowing analysis of hair segments to determine the timeline of drug use.

Question 45

What can affect the chronology of drug intake when analyzing hair for drug content?

Answer 45

Environmental exposure where drugs penetrate the hair’s surface or enter through sweat can affect drug intake chronology.

Question 46

What are some examples of non-drug poisons encountered in forensic toxicology?

Answer 46

Examples include heavy metals like arsenic, bismuth, antimony, mercury, and thallium.

Question 47

How are heavy metals screened for in forensic toxicology?

Answer 47

Screening involves dissolving the suspect body fluid in hydrochloric solution and inserting a copper strip; a dark coating on copper indicates heavy metal presence.

Question 48

How is the concentration of carbon monoxide in blood measured in forensic analysis?

Answer 48

It can be measured using spectrophotometric methods by determining carboxyhemoglobin relative to oxyhemoglobin or total hemoglobin, or by releasing carbon monoxide for measurement using gas chromatography.