Forensic Toxicology

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Forensic Toxicology
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Forensic Toxicology

• Definition
• The science of detecting and identifying the
  presence of drugs and poisons in body fluids,
  tissues, and organs.

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Controlled Substances Act

• Federal Law established 5 schedules of
  classification of controlled substances based on
• Drugs potential for abuse
• Potential to physical and psychological
  dependence
• Medical Value
• Note Federal law also controls materials that
  are used in making drugs and those that are
  manufactured to resemble drugs

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Drug Schedules

• Schedule I
• Drugs with high potential for abuse and
  addiction, NO medical value
• Ex Heroin, LSD, Ecstasy, Marijuana
• Schedule II
• Drugs with high potential for abuse and
  addiction, have some medical value with
  restrictions
• Ex PCP, Cocaine, Amphetamines, Most Opiates,
  Some Barbiturates

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Drug Schedules

• Schedule III
• Drugs with less potential for abuse and
  addiction, currently acceptable for medical use
• Ex Some Barbiturates, Codeine, Steroids
• Schedule IV
• Drugs with low potential for abuse and addiction,
  currently acceptable for medical use
• Ex Tranquilizers like Valium, Xanax, Librium

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Drug Schedules

• Schedule V
• Drugs with low potential abuse, medical use,
  lowest potential dependency
• Ex Some Opiates with Non-Narcotic Ingredients

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Role of the Toxicologist

• Must identify one of thousands of drugs and
  poisons
• Must find nanogram to microgram quantities
  dissipated throughout the entire body
• Not always looking for exact chemicals, but
  metabolites of desired chemicals (ex. heroin ?
  morphine within seconds)

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Toxicology Procedures

• 10mL of blood in airtight container
• Add anticoagulant
• Add preservative
• 2 consecutive urine samples
• Some drugs take a while to show up in urine (1-3
  days)
• Vitreous humor
• Hair samples

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Toxicology Procedures

• Screening-
• quick test to narrow down possibilities
• color tests, TLC, GC, immunoassay
• Confirmation-
• determines exact identity
• GC/Mass Spec

Note TLCthin layer chromatography
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Color Tests

• Marquis Test
• Turns purple in the presence of Heroin, morphine,
  opium
• Turns orange-brown in presence of Amphetamines
• Scott Test Three solutions
• Blue then pink then back to blue in the presence
  of Cocaine
• Duquenois-Levine
• Test for marijuana turns purple

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More Analytical Tests

• Microcrystalline Tests Identifies drug by using
  chemicals that reacts to produce characteristic
  crystals
• Chromatography TLC, HPLC and gas separate
  drugs/tentative ID
• Mass Spectrometry chemical fingerprint no two
  drugs fragment the same

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Why?

• Think of all the people that you have heard do
  drugs.
• US drug manufacturers produce enough barbiturates
  and tranquilizers each year to give every person
  in the US 40 pills
• (thats about 12 billion pills)
• 18,000 out of 44,000 annual traffic deaths are
  alcohol related and send over 2 million people to
  the hospital

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Toxicology of Alcohol

• Alcohol is absorbed through the stomach and
  intestine
• Once absorbed, alcohol is
• Oxidized- in liver by alcohol dehydrogenaseturned
  into acidic acid
• Excreted- by breath, perspiration, and
  kidneysturned into carbon dioxide and water

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Factors that Affect Alcohol Absorption

• Time of consumption
• Type of alcoholic beverage
• Presence of food in stomach

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Toxicology of Alcohol

• Alcohol intoxication depends on
• Amount of alcohol consumed
• Time of consumption
• Body weight
• Rate of alcohol absorption

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Fate of Alcohol

• Alcohol is absorbed into the bloodstream
• Distributed through-out the bodys water
• And finally eliminated by oxidation and excretion

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Fate of Alcohol Cont

• Note
• Oxidation is the combination of oxygen and
  alcohol to produce new products by the liver
• Elimination is removing alcohol from the body in
  an unchanged state normally excreted in breath
  and urine

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Alcohol in the Circulatory System

• Measuring the quantity of alcohol in the blood
  system determines the degree to which someone is
  drunk
• Two methods of making this measurement
• Measurement of alcohol content in blood
• Measurement of alcohol in breath

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Circulation and Alcohol
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Circulation and Alcohol
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Circulation Definitions

• Arterya blood vessel that carries blood away
  from the heart
• Veina blood vessel that transports blood toward
  the heart
• Capillarya tiny blood vesselwalls exchange
  materials between blood and tissues
• Alveolismall sacs in lungsexchange vapors
  between breath and blood

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Circulation Cont

• Note If alcohol is present, it will be passed
  from the blood into the alveoli where it will be
  passed on to the mouth and nose during the act
  of breathing.
• Evidence has shown that the ratio of alcohol to
  alveoli air is approx. 2100 to 1This is a basis
  for relating breath to blood-alcohol
  concentration.

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Analysis of BAC

• Breath Tests
• Field Sobriety Tests
• Blood Tests

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Breath Tests

• A breath test reflects the alcohol concentration
  in the pulmonary artery.
• One instrument used for breath tests is called
  The Breathalyzer.
• The Breathalyzer is a device for collecting and
  measuring the alcohol content of alveolar breath.

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The Breathalyzer
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The Breathalyzer Cont

• The Breathalyzer traps 1/40 of 2100 milliliters
  of alveolar breath.
• Since the amount of alcohol in 2100 milliliters
  of breath approximates the amount of alcohol in 1
  milliliter of bloodthe Breathalyzer in essence
  measures the alcohol concentration present in
  1/40 of a milliliter of blood.

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Breathalyzer Cont

• Once the alveolar breath is trapped it is allowed
  to undergo a chemical reaction

• 2K2Cr2O7 3C2H5OH 8H2SO4 ? 2Cr2(SO4)3 2K2SO4
  3CH3COOH 11H2O
• The Breathalyzer indirectly determines the
  quantity of alcohol consumed by measuring the
  absorption of light by potassium chromate before
  and after its reaction with alcohol, using the
  principle of spectrophotometry

Potassium dichromate
Ethyl alcohol
Sulfuric acid
Chromium sulfate
Potassium sulfate
Acetic acid
Dihydrogen oxide
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Other Breath Tests

• Infrared breath-testing instrument
• Fuel cell
• Note These instruments are used more recently
  because they dont depend upon chemical reagents
  and are entirely automated.

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Infrared-Breath Test

• Uses the principle that infrared light is
  absorbed when shined on alcohol
• Essentially, the infrared light passes through a
  chamber where it will interact with the alcohol
  and cause the light density to decrease.
• The decrease in light intensity is proportional
  to the concentration of alcohol present in the
  captured breath

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Fuel CellBreath Test

• A fuel cell converts a fuel and an oxidant into
  an electrical current.
• In this test, the breath alcohol is the fuel and
  atmospheric oxygen acts as the oxidant.
• Alcohol is converted, generating a current that
  is proportional to the quantity of alcohol
  present in the breath.

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Infrared and Fuel Cell Breath Tests

• Infrared Breath Test uses infrared wavelengths to
  test for alcohol or other interferences in the
  breath

• Fuel Cell Test converts fuel (alcohol) and oxygen
  into a measurable electric current

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Field Sobriety Testing

• Two reasons for the field sobriety test
• Used as a preliminary test to ascertain the
  degree of the suspects physical impairment
• To see whether or not an evidential test is
  justified.

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Field Sobriety Testing Methods

• Field sobriety testing consists of a series of
  psychophysical tests and a preliminary breath
  test (typically done with a handheld fuel cell
  tester)
• These tests are preliminary and nonevidential in
  naturethey only serve to establish probable
  cause requiring a more thorough breath or blood
  test.

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Field Sobriety Tests

• Horizontal Gaze Nystagmus
• Involuntary eye jerk as eye moves horizontally
• Walk and Turn (divided attention tasks)
• One-Leg Stand

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Parts of the brain affected by Alcohol

• Alcohol 1st affects the forebrain and moves
  backward
• Last affected is medulla oblongata

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Alcohol and the Law
At least we dont live in France, Germany,
Ireland, or Japan (0.05) or especially Sweden
(0.02)!

• 1939-1964 intoxicated 0.15 BAC
• 1965 intoxicated 0.10 BAC
• 2003 intoxicated 0.08 BAC

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Alcohol and the Law

• Try the drink wheel http//www.intox.com/wheel/dr
  inkwheel.asp

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The End