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.