Transcript Science Fair Project

Chapter 8
Toxicology:
Poisons and Alcohol
“All substances are
poisons. There is
none which is not.
The right dose
differentiates a
poison and remedy.”
—Paracelsus (1495-1541).
Swiss physician and
chemist
Toxicology
Definition—the study of the
adverse effects of chemicals
or physical agents on living
organisms.
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Toxicology
Types:
Environmental—air, water, soil
Consumer—foods, cosmetics,
drugs
Medical, clinical, forensic
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Forensic Toxicology
Postmortem—medical
examiner or coroner
Criminal—motor vehicle
accidents (MVA)
Workplace—drug testing
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Forensic Toxicology
Sports—human and animal
Environment—industrial,
catastrophic, terrorism
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Toxicology
Toxic substances
may:
Contribute to death
Be a cause of death
Cause impairment
Explain behavior
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The Severity of the Problem
“If all those buried in our
cemeteries who were
poisoned could raise their
hands, we would probably
be shocked by the
numbers.”
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—John Harris Trestrail, “Criminal Poisoning”
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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
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Aspects of Toxicity
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
Expressed in milligrams of
substance per kilogram of body
weight
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Toxicity Classes
LD50 (rat,oral)
Correlation to
Ingestion by 150
lb Adult Human
Toxicity
<1mg/kg
a taste to a drop
extremely
1-50 mg/kg
to a teaspoon
highly
50-500 mg/kg
to an ounce
moderately
500-5000 mg/kg
to a pint
slightly
5-15 g/kg
to a quart
practically non-toxic
Over 15g/kg
more than 1 quart
relatively harmless 10
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Federal Regulatory Agencies
 Food and Drug Administration (FDA)
 Environmental Protection Agency (EPA)
 Consumer Product Safety Commission
 Department of Transportation (DOT)
 Occupational Safety and Health
Administration (OSHA)
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Symptoms of Various Types
of Poisoning
Type of Poison Symptom/Evidence
 Caustic Poison (lye) Characteristic burns
around the lips and
mouth of the victim
 Carbon Monoxide
Red or pink patches on the
chest and thighs,
unusually bright red lividity
 Sulfuric acid
Black vomit
 Hydrochloric acid
Greenish-brown vomit
 Nitric acid
Yellow vomit
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Symptoms of Various Types
of Poisoning
Type of Poison Symptom/Evidence
 Phosphorous
Coffee brown vomit. Onion
or garlic odor
 Cyanide
Burnt almond odor
 Arsenic, Mercury Pronounced diarrhea
 Methyl (wood) or Nausea and vomiting,
Isopropyl (rubbing)
unconsciousness,
alcohol
possibly blindness
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Critical Information
on Poisons
Form
Common color
Characteristic odor
Solubility
Taste
Common sources
—John Trestrail from “Criminal Poisoning”
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Critical Information
on Poisons
 Mechanism
 Possible methods of administration
 Time interval of onset of symptoms.
 Symptoms resulting from an acute
exposure
 Symptoms resulting from chronic
exposure
—John Trestrail from “Criminal Poisoning”
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Critical Information
on Poisons
Disease states mimicked by
poisoning
Notes relating to the victim
Specimens from victim
Analytical detection
methods
—John Trestrail from “Criminal Poisoning”
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Critical Information
on Poisons
Known toxic levels
Notes pertinent to analysis
of poison
List of cases in which
poison was used
—John Trestrail from “Criminal Poisoning”
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To Prove a Case
 Prove a crime was
committed
 Motive
 Intent
 Access to poison
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To Prove a Case
 Access to victim
 Death was caused by
poison
 Death was homicidal
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Forensic Autopsy
Look for:
Irritated tissues
Characteristic odors
Mees lines—single
transverse white bands on
nails.
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Forensic Autopsy
Order toxicological screens
Postmortem concentrations
should be done at the scene
for comparison
No realistic calculation of dose
can be made from a single
measurement
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Human Specimens for Analysis
Blood
Urine
Vitreous Humor
of Eyes
Bile
Gastric contents
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Liver tissue
Brain tissue
Kidney
tissue
Hair/nails
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Alcohol—Ethyl Alcohol (C2H5OH)
Most abused drug in America
About 40% of all traffic deaths
are alcohol-related
Toxic—affecting the central
nervous system, especially the
brain
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Alcohol—Ethyl Alcohol (C2H5OH)
Colorless liquid, generally
diluted in water
Acts as a depressant
Alcohol appears in blood within
minutes of consumption; 30-90
minutes for full absorption
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Alcohol—Ethyl Alcohol (C2H5OH)
Detoxification—about
90% in the liver
About 5% is excreted
unchanged in breath,
perspiration and urine
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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
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BAC
Blood Alcohol Content
 Expressed as percent weight per volume of
blood
 Legal limits in all states is 0.08%
 Parameters influencing BAC:
 Body weight
 Alcoholic content
 Number of beverages consumed
 Time between consumption
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BAC
 Burn off rate of 0.015% per hour but
can vary:
 Male
BAC male = 0.071 x (oz) x (% alcohol)
body weight
 Female
BAC female = 0.085 x (oz) x (% alcohol)
body weight
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Henry’s Law
 When a volatile chemical is dissolved in a
liquid and is brought to equilibrium with air,
there is a fixed ratio between the
concentration of the volatile compound in
the air and its concentration in the liquid;
this ratio is constant for a given
temperature. THEREFORE, the
concentration of alcohol in breath is
proportional to that in the blood.
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Henry’s Law
This ratio of alcohol in the
blood to alcohol in the alveolar
air is approximately 2100 to 1.
In other words 1 ml of blood
will contain nearly the same
amount of alcohol as 2100 ml
of breath.
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Field Tests
Preliminary tests—used
to determine the degree of
suspect’s physical
impairment and whether or
not another test is justified.
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Field Tests
Psychophysical test—
3Basic Tests
 Horizontal gaze nystagmus
(HGN): follow a pen or small
flashlight, tracking left to right with
one’s eyes. In general, wavering
at 45 degrees indicates 0.10
BAC.
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Field Tests
Nine Step walk and turn
(WAT): comprehend and
execute two or more simple
instructions at one time.
One-leg stand (OLS): maintain
balance, comprehend and
execute two or more simple
instructions at one time.
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The Breathalyzer
More practical in the field
Collects and measures alcohol
content of alveolar breath
Breath sample mixes with 3 ml of
0.025 % K2Cr2O7 in sulfuric acid
and water
2K2Cr2O7 + 3C 2H5OH + 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11 H2O
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The Breathalyzer
Potassium dichromate is yellow, as
concentration decreases its light
absorption diminishes so the
breathalyzer indirectly measures
alcohol concentration by measuring
light absorption of potassium
dichromate before and after the
reaction with alcohol
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Generalizations
During absorption, the
concentration of alcohol in arterial
blood will be higher than in
venous blood.
Breath tests reflect alcohol
concentration in the pulmonary
artery.
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Generalizations
The breathalyzer also can react
with acetone (as found with
diabetics), acetaldehyde, methanol,
isopropyl alcohol, and paraldehyde,
but these are toxic and their
presence means the person is in
serious medical condition.
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Generalizations
Breathalyzers now use an
infrared light absorption
device with a digital read-out.
Prints out a card for a
permanent record.
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People in the News
John Trestrail is a practicing
toxicologist who has consulted on
many criminal poisoning cases. He is
the founder of the Center for the Study
of Criminal Poisoning in Grand
Rapids, Michigan which has
established an international database
to receive and analyze reports of
homicidal poisonings from around the
world. He is also the director of DeVos
Children’s Hospital Regional Poison
Center. In addition, he wrote the book,
Criminal Poisoning, used as a
reference by law enforcement,
forensic scientists and lawyers.
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More Information
Read more about Forensic
Toxicology from Court TV’s Crime
Library at:
http://www.crimelibrary.com/criminal_
mind/forensics/toxicology/2.html
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Chapter 7
Drugs
“Having sniffed the dead man’s
lips, I detected a slightly sour
smell, and I came to the
conclusion that he had poison
forced upon him.”
—Sherlock Holmes, in Sir Arthur Conan Doyle’s
A Study in Scarlet
Drugs and Crime
 A drug is a natural or
synthetic substance
designed to affect the
subject psychologically or
physiologically.
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Drugs and Crime
 “Controlled substances” are
drugs that are restricted by law
 Controlled Substances Act is
a law that was enacted in 1970;
it lists illegal drugs, their
category and their penalty for
possession, sale or use.
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Controlled Substances
Act
Schedule I – high potential
for abuse; no currently
acceptable medical use in
the U.S.; a lack of accepted
safety for use under medical
supervision
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Controlled Substances
Act
Schedule II – high potential
for abuse; a currently accepted
medical use with severe
restrictions; abuse may lead to
severe psychological or
physical dependence
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Controlled Substances
Act
Schedule III – lower potential
for abuse than the drugs in I or II;
a currently accepted medical use
in treatment in the U.S.; abuse
may lead to moderate physical
dependence or high
psychological dependence
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Controlled Substances
Act
Schedule IV – low potential for
abuse relative to drugs in III; a
currently accepted medical use in
treatment in the U.S.; abuse may
lead to limited physical
dependence or psychological
dependence relative to drugs in III
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Controlled Substances
Act
Schedule V – low potential for
abuse relative to drugs in IV;
currently accepted medical use in
treatment in the U.S.; abuse may
lead to limited physical
dependence or psychological
dependence relative to drugs in IV
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Examples of Controlled Substances and Their
Schedule Placement
 Schedule I—heroin
(diacetylmorphine), LSD,
marijuana, ecstasy (MDMA)
 Schedule II—cocaine,
morphine, amphetamines
(including methamphetamines),
PCP, Ritalin
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Examples of Controlled Substances and Their
Schedule Placement
 Schedule III—intermediate acting
barbiturates, anabolic steroids,
ketamine
 Schedule IV—other stimulants and
depressants including Valium,
Xanan, Librium, phenobarbital,
Darvon
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Examples of Controlled Substances and Their
Schedule Placement
 Schedule V—codeine found in
low doses in cough medicines
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Identification of Drugs
 PDR—Physicians’ Desk
Reference
 Field Tests—presumptive
tests
 Laboratory Tests—
conclusive tests
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Human Components
Used for Drug Analysis
 Blood
 Liver tissue
 Urine
 Brain tissue
 Hair
 Kidney tissue
 Gastric Contents
 Spleen tissue
 Bile
 Vitreous Humor of
the Eye
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Physicians’ Desk Reference
PDR—a physicians’ desk reference is used
to identify manufactured pills, tablets and
capsules. It is updated each year. This can
sometimes be a quick and easy identifier of
the legally made drugs that may be found
at a scene. The reference book gives a
picture of the drug, whether it is a
prescription, over the counter, or a
controlled substance; as well as more
detailed information about the drug.
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PDR Key
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Drug Identification
Screening or presumptive tests
 Spot or color tests
 Microcrystalline test—
a reagent is added that
produces a crystalline
precipitate which is unique
for a certain drug.
 Chromatography
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Drug Identification
Confirmatory tests
 Spectrophotometry
Ultraviolet (UV)
Visible
Infrared (IR)
 Mass spectrometry
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Presumptive Color Tests
 Marquis—turns
purple in the
presence of most
opium derivatives
and orange-brown
with amphetamines
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Presumptive Color Tests
 Dillie-Koppanyi—turns
violet-blue in the presence
of barbiturates
 Duquenois-Levine—
turns a purple color in the
presence of marijuana
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Presumptive Color Tests
 Van Urk—turns a bluepurple in the presence of
LSD
 Scott test—color test for
cocaine, blue
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Chromatography
 A technique for separating
mixtures into their components
 Includes two phases—a mobile
one that flows past a stationary
one.
 The mixture interacts with the
stationary phase and separates.
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Types of Chromatography
 Paper
 Thin Layer (TLC)
 Gas (GC)
 Pyrolysis Gas (PGC)
 Liquid (LC)
 High Pressure Liquid (HPLC)
 Column
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Paper Chromatography
 Stationary phase—
paper
 Mobile phase—a
liquid solvent
Capillary action moves
the mobile phase
through the stationary
phase
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Thin Layer Chromatography
 Stationary phase— a
thin layer of coating
(usually alumina or
silica) on a sheet of
plastic or glass
 Mobile phase—
a liquid solvent
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People of Historical
Significance
Francis William Aston was a British
physicist who won the 1922 Nobel
Prize in Chemistry for his work in the
invention of the mass spectrograph.
He used a method of electromagnetic
focusing to separate substances.
This enabled him to identify no fewer
than 212 of the 287 naturally
occurring elemental isotopes.
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