FORENSIC TOXICOLOGY

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FORENSIC TOXICOLOGY

• Chapter 6

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Toxicology
Toxicologythe study of the adverse effects of
chemicals or physical agents on living organisms.
Video Types Environmentalair, water,
soil Consumerfoods, cosmetics, drugs Medical,
clinical, forensic
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Toxicologists

• Toxicologists are charged with the responsibility
  for detecting and identifying the presence of
  drugs and poisons in body fluids, tissues, and
  organs. Video
• Toxicologists not only work in crime laboratories
  and medical examiners offices, but may also
  reach into hospital laboratories and health
  facilities to identify a drug overdose or monitor
  the intake of drugs. Careers video

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Mathieu Orfilia Father of Tox

• The father of toxicology was Mathieu Orfilia in
  the early 1800s .
• His work mainly centered around arsenic.
• It was relatively easy to get because it was the
  rat poison of the day and was the favorite murder
  weapon among poor people.

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Intoxicant vs. Poison

• An intoxicant such as alcohol requires that a
  relatively large amount be added to be lethal.
• A poison, like cyanide, requires a relatively
  small amount to be fatal.

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Forensic Toxicology found in
Postmortemmedical examiner or coroner Criminalmo
tor vehicle accidents (MVA) Workplacedrug
testing Sportshuman and animals Environmentindus
trial, catastrophic, terrorism. Video link
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Environmental Example Love Canal New York
An example of where forensic toxicology impacts
the population is the Love Canal Disaster. Video
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Toxicology
Toxic substances may Be a cause of
death Contribute to death Cause
impairment Explain behavior
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Life Example Carbon Monoxide
Video Link
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Aspects of Toxicity
Dosage The chemical or physical form of the
substance The mode of entry into the body Body
weight and physiological conditions of the
victim, including age and sex The time period of
exposure The presence of other chemicals in the
body or in the dose
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Lethal Dose
LD50 refers to the dose of a substance that kills
half the test population, usually within four
hours. Testing is usually done on animals that
compare well to humans metabolism. Expressed in
milligrams of substance per kilogram of body
weight
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Toxicity Classification
LD50 (rat,oral) Correlation to Ingestion by 150-lb Adult Human Toxicity
lt1 mg/kg a taste to a drop extreme
150 mg/kg to a teaspoon high
50500 mg/kg to an ounce moderate
5005,000 mg/kg to a pint slight
515 g/kg to a quart practically nontoxic
Over 15 g/kg more than 1 quart relatively harmless
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Symptoms of Various Types of Poisoning

• Type of Poison
• 1. Caustic poison (lye) Characteristic burns
  around the lips and mouth of victim
• 2. Carbon monoxide Red or pink patches on the
  chest and thigh, unusually bright red lividity
• 3. Sulfuric acid Black vomit
• 4. Hydrochloric acid Greenish-brown vomit
• 5. Cyanide- Seizures, Burnt almond odor
• 6. Arsenic diarrhea, vomiting, blood in the
  urine, cramping muscles, stomach pain, and
  convulsions.
• 7. Methyl (wood) or isopropyl (rubbing) alcohol
  Nausea and vomiting, unconsciousness possibly
  blindness

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To Prove a Case
Prove a crime was committed Motive Intent Access
to poison Access to victim Death was
homicidal Death was caused by poison
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AlcoholEthyl Alcohol (C2H5OH)
Most abused drug in America About 40 percent of
all traffic deaths are alcohol-related. Acts as
a depressant Toxicaffecting the central nervous
system, especially the brain Colorless liquid,
generally diluted in water Alcohol appears in
blood within minutes 3090 minutes for full
absorption Detoxificationabout 90 percent in the
liver
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Introduction

• A major branch of forensic toxicology deals with
  the measurement of alcohol in the body for
  matters that pertain to violations of criminal
  law.

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Rate of Absorption
Depends on Amount of alcohol consumed The
alcohol content of the beverage Time taken to
consume it Quantity and type of food present in
the stomach Physiology of the consumer About 5
percent is excreted unchanged in breath,
perspiration, and urine
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Toxicology of Alcohol

• The analysis of alcohol exemplifies the primary
  objective of forensic toxicologythe detection
  and isolation of drugs in the body for the
  purpose of determining their influence on human
  behavior.
• Alcohol, or ethyl alcohol, is a colorless liquid
  normally diluted with water and consumed as a
  beverage.
• Like any depressant, alcohol principally effects
  the central nervous system, particularly the
  brain.

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Alcohol on the Breath

• A major branch of forensic toxicology deals with
  the measurement of alcohol in the body for
  matters that pertain to violations of criminal
  law.

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Alcohol Circulatory System

• Humans have a closed circulatory system
  consisting of a heart, arteries, veins, and
  capillaries.

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Alcohol Circulatory System

• Alcohol is absorbed from the stomach and small
  intestines into the blood stream.
• Alcohol is carried to the liver where the process
  of its destruction starts.

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Alcohol Circulatory System

• Blood, carrying alcohol, moves to the heart and
  is pumped to the lungs.

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Alcohol Circulatory System

• In the lungs, carbon dioxide and alcohol leave
  the blood and oxygen enters the blood in the air
  sacs known as alveoli.
• Then the carbon dioxide and alcohol are exhaled
  during breathing.

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Toxicology of Alcohol

• The analysis of alcohol exemplifies the primary
  objective of forensic toxicologythe detection
  and isolation of drugs in the body for the
  purpose of determining their influence on human
  behavior. Video
• Alcohol, or ethyl alcohol, is a colorless liquid
  normally diluted with water and consumed as a
  beverage.

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Breath Testers

• Breath testers that operate on the principle of
  infrared light absorption are becoming
  increasingly popular within the law enforcement
  community.

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Toxicology of Alcohol

• Like any depressant, alcohol principally effects
  the central nervous system, particularly the
  brain.

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Alcohol Levels

• Then the alcohol concentration slowly decreases
  until a zero level is again reached.
• Factors such as time taken to consume the drink,
  the alcohol content, the amount consumed, and
  food present in the stomach determine the rate at
  which alcohol is absorbed.

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Alcohol Levels

• Elimination of alcohol throughout the body is
  accomplished through oxidation and excretion.
• Oxidation takes place almost entirely in the
  liver, while alcohol is excreted unchanged in the
  breath, urine, and perspiration.
• The extent to which an individual may be under
  the influence of alcohol is usually determined by
  either measuring the quantity of alcohol present
  in the blood system or by measuring the alcohol
  content in the breath.

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Alcohol Levels

• Experimental evidence has verified that the
  amount of alcohol exhaled in the breath is in
  direct proportion to the blood concentration.

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Alcohol and Law

• The American Medical Association and the National
  Safety Council have been able to exert
  considerable influence in convincing the states
  to establish uniform and reasonable blood-alcohol
  standards.
• Between 1939 and 1964 a person having a
  blood-alcohol level in excess of 0.15 percent w/v
  was to be considered under the influence, which
  was lowered to 0.10 percent by 1965.
• In 1972 the impairment level was recommended to
  be lowered again to 0.08 percent w/v. It remains
  there today.

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Alcohol and Law

• To prevent a persons refusal to take a test for
  alcohol consumption, the National Highway Traffic
  Safety Administration recommended an implied
  consent law.
• Adopted by all states by 1973, this law states
  that the operation of a motor vehicle on a public
  highway automatically carries with it the
  stipulation that a driver will submit for a test
  for alcohol intoxication if requested or be
  subject to loss of the license.

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Breath Testers

• Many types of breath testers are designed to
  analyze a set volume of breath.
• The captured breath is exposed to infrared light.
  

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Breath Testers

• Its the degree of the interaction of the light
  with alcohol in the captured breath sample that
  allows the instrument to measure a blood alcohol
  concentration in breath.
• Some breath testing devices also use fuel cells.

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Field Testing

• Law enforcement officers typically use field
  sobriety tests to estimate a motorists degree of
  physical impairment by alcohol and whether or not
  an evidential test for alcohol is justified.
• The horizontal gaze nystagmus test, walk and
  turn, and the one-leg stand are all considered
  reliable and effective psychophysical tests.

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Gas Chromatography Testing

• Gas chromatography offers the toxicologist the
  most widely used approach for determining alcohol
  levels in blood.

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Gas Chromatography Testing

• Blood must always be drawn under medically
  accepted conditions by a qualified individual.
• It is important that a nonalcoholic disinfectant
  be applied before the suspects skin is
  penetrated with a sterile needle or lancet.
• Once blood is removed from an individual, its
  preservation is best ensured when it is sealed in
  an airtight container after an anticoagulant and
  a preservative have been added and stored in a
  refrigerator.

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The Confirmation Step

• The GC separates the sample into its components,
  while the MS represents a unique fingerprint
  pattern that can be used for identification.
• Once the drug is extracted and identified, the
  toxicologist may be required to provide an
  opinion on the drugs effect on an individuals
  natural performance or physical state.