Forensic Toxicology Section 1

							      Forensic Toxicology
      Section 1
                                  Objectives
            1.   Explain how alcohol is absorbed into the
                 bloodstream, transported throughout the body,
                 and finally eliminated by oxidation and
                 excretion.
            2.   Name the important parts of the human
                 circulatory system.
            3.   Describe the process by which alcohol is
                 excreted in the breath via the alveoli.
            4.   Describe the design of the Breathalyzer.
            5.   Explain the significance of a chemical equation.
            6.   Explain the concept of infrared and fuel-cell
                 breath-testing devices.
            7.   Demonstrate some common field sobriety tests.
            8.   List common laboratory procedures for
                 measuring alcohol’s concentration in the blood.
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Role of Forensic Toxicology

    Uncontrolled use of drugs has
    increased world wide importance of
    the field
            Toxicologist
              detect and identify drugs and poisons in
              body fluids, tissues, and organs
               –   test lead exposure in children
               –   urine/blood analysis for drug treatment programs
               –   urine/blood analysis of prospective employees
               –   urine/blood analysis of competitive athletes

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Toxicology of Alcohol
    Ethyl alcohol – most abused drug
            responsible for 40% of traffic deaths
               17,500 fatalities per year
            hospitalizations from injuries
               2 million per year
    Metabolism
            chemical reactions in an organism
    Alcohol Metabolism
            absorption – how it gets into systems
            distribution – how it moves through body
            elimination – how it is removed from body

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Alcohol Metabolism
    Absorption
            slowly enters
            bloodstream
               in stomach
               in small intestines
            Factors affecting
            adsorption:
               time taken to consume
               amount consumed
               alcohol content of
               beverage
               quantity and type of food
               in stomach

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Alcohol Metabolism (con’t)
    Distribution
            equally distributed into watery parts of (2/3)
            body
    Elimination (0.015% per weight/volume
    per hour)
            Oxidation in liver (95-98%)
               alcohol dehydrogenase
                 – alcohol  acetaldehyde  acetic acid
                 – acetic acid  carbon dioxide and water
            Excretion
               lungs (breath)
               kidneys (urine)
               sweat glands (perspiration)

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Blood Alcohol Concentration

How much alcohol impairs brain function
       [blood alcohol] directly proportional [brain
       alcohol]
       maximum [blood alcohol] may not be
       reached for 2-3 hours after consumption
       usually 20-30 minutes after final drink
       absorption is completed



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Alcohol Ingestion and Distribution

    Closed Circulatory
    System
            heart (pump)
            arteries - carry blood
            away from heart
            capillaries - exchange
            blood with tissue
            veins - returns blood
            from tissues to heart


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Alcohol Aeration
    Lungs
            alveoli
               oxygen and carbon
               dioxide exchange
            Henry’s Law
               volatile in liquid reached
               equilibrium with air at a
               fixed ratio that is constant
               at a given temperature
               at 34°C ratio is 2100 to 1
               so that 1 mL of blood has
               the same [alcohol] as
               2100 mL of breath
               basis of breathalyzer tests


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Alcohol Recirculation and
Adsorption
    arterial blood sends alcohol to tissues
            [alcohol] in arteries > [alcohol] in veins
              up to 41% higher 30 mins after last drink
            does not equalize until adsorption stage
            is completed




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Breath Testing for Alcohol
    Measures [alcohol] in pulmonary
    artery by measuring [alcohol] in
    alveolar breath
            during absorptive phase will be higher
            than [alcohol] in veins
            Breathalyzer
              developed 1954 by R. Borkenstein of
              Indiana State Police
            Infrared Light Absorption Devices
            Fuel Cell Detectors
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Breathalyzer Test
                                   52.5 mL collected
                                          passed through
                                          potassium dichromate
                                          reacts with alcohol
                                          forming acetic acid
                                          silver nitrate acts as
                                          catalyst
                                          2 to 3 ratio
                                          for every 2 units of
                                          potassium dichromate
                                          used 3 units of alcohol
                                          was present


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Infrared Light Adsorption Devices

    microprocessor
    controlled
    self calibrating
            breath collected
            IR light passed through
            chamber
            filter selects IR
            wavelength alcohol
            absorbed
            detector measures
            alcohol present

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Fuel Cell Device

    microprocessor controlled
    self calibrating
            platinum electrodes
            separated by porous acid or base
            containing membrane
            alcohol  acetic acid + free electrons
            current formed is proportional to alcohol
            in breathe

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Consideration in Breath Testing

    need alveolar breathe (1.1 – 1.6 L)
            slope detector insures this
    avoid “mouth alcohol”
            regurgitation, mouth wash, etc
            observe 15 to 20 minutes before test
    take duplicate samples



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Field Sobriety Testing
    psychophysical tests
            degree of impairment
            whether evidential test justified
    Alco-Sensor FST
    Horizontal-gaze Nystagmus
            involuntary jerk moving eye
    Walk and Turn
            heel to toe walk for nine steps
            turn and heel to toe walk back
    One-Leg Stand
            stand on one foot and count out loud


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      Forensic Toxicology
      Section 2
                                     Objectives
            1.   Describe the precautions to be taken to properly
                 preserve blood for analysis for its alcohol content.
            2.   What is the presumptive impairment level for blood
                 alcohol in your state?
            3.   Explain the significance of the implied consent law
                 and the Schmerber v. California case to traffic
                 enforcement.
            4.   Define acid and base.
            5.   Develop an appreciation for the role of the toxicologist
                 in the criminal justice system.
            6.   Describe some of the techniques that forensic
                 toxicologists use for isolating and identifying drugs
                 and poisons.
            7.   Discuss the significance of finding a drug in human
                 tissues and organs.
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Analysis of Blood for Alcohol
    gas chromatography
            alcohol has definite
            peak
            peak size can be
            compared to knowns
    alcohol
    dehydrogenase NAD
    reaction
            converts NAD to
            NADH
            measurable by
            spectrophotometer

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Collection and Preservation of
Blood
    blood drawn by qualified person
    use nonalcoholic disinfectant
            Zepiran or Betadine
    sealed in airtight container
            anticoagulant (EDTA potassium oxalate)
            preservative (sodium fluoride)
    refrigerate
    postmortem
            bacteria produce ethanol
            prefer vitreous humor or urine to limit this effect
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Alcohol and the Law
AMA and NSC
       establish uniform / reasonable
       blood alcohol levels
Blood-Alcohol Laws
       AMA NSC
            0.15% w/v under influence
       1992 DOT recommends lower
            0.08% w/v under influence
              – 2003 states not lose fed funds
       Commercial Drivers
            0.04% w/v under influence




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Constitutional Issues
    Fifth Amendment
            protects from self-incrimination
    NSTA implied-consent law
            refusing test leads to loss of license
            Schmerber vs. California
               blood take w/o consent after accident led to
               conviction
               Supreme Court
                 – 5th Amendment prohibits testimonial self incrimination
                 – does not apply to furnishing physical evidence
                 – 4th Amendment (unreasonable search)
                      » emergency situation warranted taking
                      » taken in accepted manner without unreasonable
                        force

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Role of Toxicologist

    w/o clue needs extensive “screening”
    using small amounts
            micrograms if not nanograms
    body actively alters substances
            i.e. heroin is immediately metabolized to
            morphine which can combine with carbs
            in body and not end up in urine samples


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Toxicological Techniques
    Acid/Base
            control pH affects drug removal
               Acid – barbiturates and aspirin
               Basic – phencyclidine, methadone, amphetamine, cocaine
    Screening Tests
            TLC, GC, Immunoassay (monoclonal antibodies)
    Confirmation Tests
            GC followed by MS
    Hair Analysis
            used for measuring long term abuse




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Other techniques
    Reinsch Test
            screens for heavy metals
              treat body fluid with HCl
                – copper strip in fluid darkens heavy metal present
                – followed with more detailed inorganic analysis

    CO poisoning
            spectrophotometer
            reagent followed by GC
              find percent saturation
                – 35-40 percent is fatal
                – 8-10 percent seen in chain smokers

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