Chapter Fourteen – Forensic Toxicology

FRSC 8104Criminalistics II

Professor Bensley

FRSC 8104 – Toxicology Objectives1. Describe the role of the forensic toxicologist in the following:

Postmortem Examinations, Human Performance Testing, and Workplace Drug Testing.

2. Describe the various biological matrices on which toxicological analyses are routinely performed.

3. Explain how alcohol is produced, how it is absorbed into the bloodstream, how it is transported throughout the body, and how it is eliminated by oxidation and excretion.

4. Describe the basic fundamental concepts of breath alcohol testing procedures (BrAC).

5. Relate the precautions to be taken to properly preserve blood samples in order to accurately analyze its alcohol content.

FRSC 8104 – Toxicology Objectives6. Describe techniques that forensic toxicologists use to isolate

and identify drugs and poisons.7. Appreciate the significance of finding a drug in human tissues

and organs to in relation to assessing level of impairment.

FRSC 8104 – Toxicology OutlineI. Introduction

A. Definition of toxicologyB. Three areas of forensic toxicologyC. Role of the toxicologistD. Toxicology vs. Pharmacology

II. All Substances are Poisons?A. Therapeutic LevelsB. Lethal Dose (LD50)

Typical Dose Response Curve

(NOAEL) = No observed adverse effect level

(LOAEL) = Lowest observed adverse effect level

LD-50

FRSC 8104 – Toxicology Outline

III. Parmacokinetics – Study of how drugs move into and out of body

A. Absorption - All introduction methods result in passage of drug through a tissue barrier and into the bloodstream

B. DistributionC. MetabolismD. Elimination

FRSC 8104 – Toxicology Outline

IV. Pharmacodynamics – Study of how drugs act in the body

A. Receptors, Agonists, and AntagonistsB. ToleranceC. Synergism

FRSC 8104 – Toxicology OutlineV. Sample/Specimen Collection

VI. Post Mortem Forensic ToxicologyA. Types of casesB. SpecimensC. Analytical ProcessD. Analytes

FRSC 8104 – Toxicology OutlineVII.Human Performance Testing (Behavioral

Toxicology)A. Steroids

1. Corticosteroids2. Anabolic Steroids3. Prohormones and Designer Steroids

Anabolic Steroids

Steroid Synthesis

Hormone Synthesis

Prohormones

FRSC 8104 – Toxicology OutlineB. Growth Hormones (HGH)

FRSC 8104 – Toxicology OutlineC. Alcohol (Ethanol)

1. Absorption of Ethanola. Ingestionb. Metabolismc. Oxidationd. Full vs. Empty

Stomache. Factors determining

absorption rate

Ethanol Oxidation

Ethanol Absorption (Widmark) Curve

The effect of food on blood alcohol concentration. The graph shows BAC after a person drank alcohol following an overnight fast (solid line) and immediately after breakfast (dotted line).

FRSC 8104 – Toxicology Outline

2. Distribution of Ethanol3. Excretion of Ethanol4. Circulation of Ethanol

a. Direct analysis of Bloodb. Alcohol content of Breath

5. Analysis of Ethanola. Field Sobriety Testsb. Breath Tests (BrAC)

FRSC 8104 – Toxicology Outlinei. Breathalyzer

FRSC 8104 – Toxicology Outlinec. Blood Alcohol Concentration (GC-FID)

i. Extractionii. Distillationiii. Direct Injection of blood or serumiv. Head Space Procedures

FRSC 8104 – Toxicology Outlinev. Quantitative Analysis Proceduresvi. External vs. Internal Standardvii. Plasma/serumviii. Reporting resultsix. Sample Preservation (Anticoagulants and

Preservatives)7. Alcohol Impairment

FRSC 8104 – Toxicology OutlineVIII.Workplace Drug Testing

A. NIDA – 5 classes of drugsB. Test Types

1. Urine2. Saliva3. Hair4. Blood5. Sweat (Patch)

SUBSTANCE BLOOD SALIVA SWEAT URINE HAIR Shortest Detectability - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > Longest Detectability

Alcohol 12 hrs 6-12 hrs unknown 6-24 hrs n/a

Amphetamine 12 hrs 3 days unknown 1-4 days up to 90 days

Barbiturates unknown unknown unknown 1-21 days unknown

Benzodiazepines unknown unknown unknown 1-42 days unknown

Cannabis (single use) 2-3 days 12-24 hrs unknown 2-3 days up to 90 days

Cannabis (habitual use) 2 weeks 12-24 hrs unknown 15-30 days up to 90 days

Cocaine unknown 1 day unknown 4-5 days up to 90 days

Codeine/Morphine unknown 12-36 hrs unknown 2-4 days up to 90 days

Heroin unknown unknown unknown 2-4 days up to 90 days

Methamphetamine 1-3 days unknown unknown 3-5 days up to 90 days

PCP 1-3 days 3 days unknown 3-7 days up to 90 days

http://www.erowid.org/psychoactives/testing/testing_info1.shtml

FRSC 8104 – Toxicology OutlineC. Classes of Drugs Tested

1. Cannabanoids

Delta-9-THC

FRSC 8104 – Toxicology Outline2. Cocaine

FRSC 8104 – Toxicology Outline3. Amphetamines

Methamphetamine vs. NeurotransmittersMethamphetamine

Dopamine Epinephrine

FRSC 8104 – Toxicology Outline4. Opiates

FRSC 8104 – Toxicology Outline5. Phencyclidine (PCP)

FRSC 8104 – Toxicology Outline6. Others

C. Methods of Analysis1. Extraction Methods2. Screening Methods

a. Immunoassay (EMIT, ELISA, RIA)

3. Confirmation4. Field Tests5. Special Considerations

At-Home Drug Test Kits

Drug Screening Urine Cutoffs (ng/mL)

Analyte Tested in Confirmation

Confirmation Cutoffs (ng/mL)

Urine Detection Time

Amphetamine 1,000 Amphetamine 500 2-4 days

Cocaine 300 Benzoylecgonine 150 1-3 days

Heroin 300 Morphine;6-monoacetylmorphine

300;10 1-3 days

Marijuana 50-20 Tetrahydrocannabinol 15 1-3 days (casual), 30 days (chronic)

Methamphet-amine

1,000 Methamphetamine;Amphetamine

500; 200 2-4 days

PCP 25 Phencyclidine 25 2-7 days (casual)

http://www.nida.nih.gov/pdf/monographs/monograph167/108-129_Cone.pdf