Transcript Forensic Toxicology - St. Edward's University

Lecture: Forensic Toxicology Poisons & Alcohol
Toxicology is defined as the study of the
adverse effects of chemicals on living
organisms.
Forensic toxicology is defined as the
application of toxicology for the purposes of
the law.
Postmortem forensic toxicology.
Human performance toxicology.
Forensic drug testing.
History
 Ancient Egyptians and Grecians reported
poisonings due to herbs, plants and food.
 Opium, arsenic and hydrocyanic acid were used
throughout Europe during the middle ages.
 Philippus Theophrastus Aureolus Bombastus von
Hohenheim (or Paracelsus) observed that any
substance could be a poison, depending on its dose
 “ What is there that is not poison? All things are
poison and nothing without poison. Solely the dose
determines that a thing is not a poison”
Postmortem Forensic
Toxicology
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Suspected drug intoxication cases
Homicides
Arson fire deaths
Motor vehicle fatalities
Deaths due to natural causes
Specimens
 Blood – from the heart and from the femoral or
jugular veins
 Vitreous humor
 Urine
 Bile
 Liver
 Other – lung, spleen, stomach contents or brain
Postmortem Forensic
Toxicology
 Specimens
 Blood – from the heart and from the
femoral or jugular veins
 Vitreous humor
 Urine
 Bile
 Liver
 Other – lung, spleen, stomach contents
or brain
Postmortem Forensic
Toxicology
 Analytical Process
 Separation
 Identification
 Confirmation
 Quantitation
Postmortem Forensic
Toxicology
 Analytes
 Volatiles (Carbon Monoxide,
Cyanide, and Alcohols)
 Drugs
 Metals
 Drugs
 One Comprehensive
Approach:
Postmortem Forensic
Toxicology
 Drugs
 One Comprehensive Approach:
Postmortem Forensic
Toxicology
 Metals
 Aluminum
 Arsenic
 Iron
 Mercury
 Lead
 Thallium
 Analysis
 Colorimetric
 Graphite Furnace Atomic Absorption
Spectrometry
 Inductively Coupled Plasma – Mass
Spectrometry
 Neutron Activation Spectrometry
Human Performance
Toxicology
 Human performance toxicology is also referred to as behavioral toxicology.
 It is the study of human performance under the influence of drugs
.
 Ethanol and driving
 History
 Behavioral effect
 Specimens
 Types of alcohol
 Ethanol (ethyl alcohol)
 Methanol (methyl alcohol)
 Isopropanol
 Ethylene glycol
Ethanol Toxicology
 Ethanol production
 Fermentation of sugar or starch
Can only achieve 20% ethanol
 Distillation
Distilled alcoholic beverages are usually
40 to 50% ethanol by volume (80-100
proof)
Ethanol
Pharmacokinetics
 Absorption
 Means of absorption
Dermal
Inhalation
IV
Oral
 Gastrointestinal tract
 Presence of food.
 Distribution
 Gastrointestinal
tract
 Portal vein
 Liver
 Heart
 Lung
 Heart
 Body
Ethanol Pharmacokinetics
 Elimination
 5-10% in the urine
 Saliva, expired air and
sweat
 Liver (enzymatic
oxidation to
acetaldehyde, acetic acid
and carbon dioxide)
Ethanol Effects on the Body
 Cardiovascular system
 Central nervous system
 Gastrointestinal tract
 Kidney
 Liver
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Breath
Ethanol
Testing
Theory
 Henry’s law
 Ethanol in breath Vs ethanol in blood
 2100 to 1 ratio
 2300 to 1 ratio
 Types of analyzers
 Chemical
 Reaction of ethanol with potassium
dichromate/sulfuric acid solution
 Colored solution that results is measured
spectrophotometrically
 IR spectrophotometry
 Electrochemical oxidation - fuel cell
Breath Ethanol Testing
 IR Spectrophotometry
 Based on absorbance of light by the
ethanol molecule
 Mainstay in evidential breath testing
devices
 Electrochemical Oxidation
 Oxidation of ethanol to acetic acid
 Also used in evidential breath testing
Blood Ethanol Testing
 Chemical
 Screening
 Quantitative
 Disadvantage - aldehydes
and ketones will interfere
with the test
 Enzymatic
 Conversion of NAD to NADH by
ethanol (serum, urine and whole blood)
 Measured spectrophotometrically at
340 nm
 Same reaction with a blue dye (thiazoyl
blue) (serum, urine, fresh blood and
postmortem blood)
 Measured with a fluorometer
 Gas Chromatography
 Can measure ethanol in a
wide range of specimens
 Can distinguish ethanol from
other alcohols, aldehydes and
ketones
 Two common methods
Head space
Direct injection
MEK(ISTD) (5.584 min.)
ACETONE (2.462 min.)
2-PROPANOL (2.804 min.)
ACETALDEHYDE (1.414 min.)
EHTANOL (1.787 min.)
0
Blood Ethanol Testing
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Assessment of Ethanol
Impairment
 In a British study:
 Detectable deterioration
of drivers at between 30
– 50 mg/dL
 Obvious deterioration
observed at between 60
– 100 mg/dL
 In another British study:
 Pilots exhibited
impairment at 40 mg/dL
 Blood alcohol concentration:
 10-50 mg/dL: Impairment detectable by
special tests
 30-120 mg/dL: Beginning of sensorymotor impairment
 90-250 mg/dL: Sensory-motor
incoordination; impaired balance
 180-400 mg/dL: Increased muscular
incoordination; apathy; lethargy
 250-400 mg/dL: Impaired consciousness;
sleep; stupor
 350-500 mg/dL: Complete
unconsciousness; coma
 450 and greater mg/dL: Death from
respiratory arrest
Stages of Acute Alcohol Intoxication*
Blood-Alcohol
Concentration
g/ 100mL
0.01-0.05
Stage of
Alcoholic
Influence
Sub clinical
Clinical Signs/ Symptoms
Influence/ effects not apparent or obvious
Behavior nearly normal by ordinary observation
Impairment detectable by special tests
0.03-0.12
Euphoria
Mild euphoria, sociability, talkativeness
Increased self-confidence; decreased inhibitions
Diminution of attention, judgment, and control
Beginning of sensory-motor impairment
Slowed information processing
Loss of efficiency in critical performance tests
0.09-0.25
Excitement
Emotional instability; loss of critical judgment
Impairment of perception, memory, and comprehension
Decreased sensory response; increased reaction time
Reduced visual acuity, peripheral vision, and glare
recovery
Sensory-motor incoordination; impaired balance
Drowsiness
0.18-0.30
Confusion
Disorientation, mental confusion; dizziness
Exaggerated emotional states (fear, rage, grief, etc.)
Disturbances of vision (diplopia, etc.) and of perception of
color, form, motion, dimensions
Increased pain threshold
Increased muscular incoordination; staggering gait; slurred
speech
Apathy, lethargy
0.25-0.40
Stupor
General inertia; approaching loss of motor functions
Markedly decreased response to stimuli
Marked muscular incoordination; inability to stand or walk
Vomiting; incontinence of urine and feces
Impaired consciousness; sleep or stupor
0.35-0.50
Coma
Complete unconsciousness; coma; anesthesia
Depressed or abolished reflexes
Subnormal temperature
Impairment of circulation and respiration
Possible death
0.45+
Death
Death from respiratory arrest
*Reprinted by permission of K.M. Dubowski, 1997.
Human Performance
Toxicology
 Drug Recognition Evaluation - 12 Step
Process
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Breath alcohol test
Interview of the arresting officer.
Preliminary examination of the suspect.
Examination of the eyes.
Divided attention psychophysical tests.
Vital signs examination.
Dark room examination.
Examination of muscle tone.
Examination for injection sites.
Suspect’s statements and other observations.
Opinion of the evaluator.
Toxicological examination.