lecture: forensic toxicology - poisons & alcohol toxicology is defined as the study of the...
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Lecture: Forensic Toxicology - Poisons & Alcohol
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.
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.
HistoryHistory 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
Postmortem Forensic Toxicology
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
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
Postmortem Forensic Toxicology
Analytical Process Separation
Identification
Confirmation
Quantitation
Postmortem Forensic Toxicology
Postmortem Forensic Toxicology
Analytes Volatiles (Carbon Monoxide,
Cyanide, and Alcohols)
Drugs
Metals
Drugs One Comprehensive
Approach:
Postmortem Forensic Toxicology
Postmortem Forensic Toxicology
Drugs One Comprehensive Approach:
Postmortem Forensic Toxicology
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
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 ToxicologyEthanol Toxicology
Ethanol production Fermentation of sugar or starch
Can only achieve 20% ethanol
DistillationDistilled alcoholic beverages are usually
40 to 50% ethanol by volume (80-100 proof)
Ethanol Pharmacokinetics
Ethanol Pharmacokinetics
Absorption Means of absorption
Dermal Inhalation IVOral
Gastrointestinal tract Presence of food.
Distribution Gastrointestinal tract Portal vein Liver Heart Lung Heart Body
Ethanol PharmacokineticsEthanol 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 BodyEthanol Effects on the Body
Cardiovascular system
Central nervous system
Gastrointestinal tract
Kidney
Liver
Breath Ethanol TestingBreath 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 TestingBreath 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 TestingBlood 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
Blood Ethanol TestingBlood Ethanol Testing
Gas Chromatography Can measure ethanol in a
wide range of specimens Can distinguish ethanol from
other alcohols, aldehydes and ketones
Two common methodsHead spaceDirect injection
AC
ET
AL
DE
HY
DE
(1.
414
min
.) EH
TA
NO
L (
1.78
7 m
in.)
2-P
RO
PA
NO
L (
2.80
4 m
in.)
ME
K(I
ST
D)
(5.5
84 m
in.)
AC
ET
ON
E (
2.46
2 m
in.)
0 6
Assessment of Ethanol Impairment
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 sensory-motor
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*
*Reprinted by permission of K.M. Dubowski, 1997.
Death from respiratory arrestDeath0.45+
Possible deathImpairment of circulation and respirationSubnormal temperatureDepressed or abolished reflexesComplete unconsciousness; coma; anesthesiaComa0.35-0.50
Impaired consciousness; sleep or stuporVomiting; incontinence of urine and fecesMarked muscular incoordination; inability to stand or walkMarkedly decreased response to stimuliGeneral inertia; approaching loss of motor functionsStupor0.25-0.40
Apathy, lethargy
Increased muscular incoordination; staggering gait; slurredspeech
Increased pain threshold
Disturbances of vision (diplopia, etc.) and of perception ofcolor, form, motion, dimensions
Exaggerated emotional states (fear, rage, grief, etc.)Disorientation, mental confusion; dizzinessConfusion0.18-0.30
DrowsinessSensory-motor incoordination; impaired balance
Reduced visual acuity, peripheral vision, and glarerecovery
Decreased sensory response; increased reaction timeImpairment of perception, memory, and comprehensionEmotional instability; loss of critical judgmentExcitement0.09-0.25
Loss of efficiency in critical performance testsSlowed information processingBeginning of sensory-motor impairmentDiminution of attention, judgment, and controlIncreased self-confidence; decreased inhibitionsMild euphoria, sociability, talkativenessEuphoria0.03-0.12
Impairment detectable by special testsBehavior nearly normal by ordinary observationInfluence/effects not apparent or obviousSub clinical0.01-0.05
Clinical Signs/Symptoms
Stage ofAlcoholicInfluence
Blood-AlcoholConcentrationg/100mL
Human Performance Toxicology
Human Performance Toxicology
Drug Recognition Evaluation - 12 Step Process 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.