Download Toxicology Notes 2012

Chapter 6
FORENSIC TOXICOLOGY
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-1
Toxicology
Toxicology— the study of the adverse
effects of chemicals or physical agents
on living organisms. Video
Types:
Environmental — air, water, soil
Consumer — foods, cosmetics, drugs
Medical, clinical, forensic
2
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-2
Toxicologists
• Toxicologists detect and identify the presence
of drugs and poisons in body fluids, tissues, and
organs.
• 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-3
Mathieu Orfilia – Father of Tox
• The father of toxicology was Mathieu
Orfilia in the early 1800’s .
• 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-4
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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-5
Forensic Toxicology found in
Postmortem —medical examiner or coroner
examines body after death
Antemortem —doctors/scientists examine the
living body before death
Environment — scientists examine industrial,
catastrophic, terrorist events
6
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-6
Environmental Example:
Love Canal New York
An example of where forensic toxicology
impacts the population is the Love Canal
Disaster. https://www.youtube.com/watch?v=Kjobz14i8kM
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-7
Toxicology
Toxic substances may:
*Be a cause of death
*Contribute to death
*Cause impairment
*Explain behavior
8
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-8
Life Example: Carbon Monoxide:
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-9
Aspects of Toxicity
• Dosage - how much
• 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
10
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-10
Lethal Dose
LD50 (Leathal Dose 50%)
• 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 (mg/kg)
11
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-11
Toxicity Classification
LD50 (rat,oral)
Correlation to Ingestion
by 150-lb Adult Human
Toxicity
<1 mg/kg
a taste to a drop
extreme
1–50 mg/kg
to a teaspoon
high
50–500 mg/kg
to an ounce
moderate
500–5,000 mg/kg
to a pint
slight
5–15 g/kg
to a quart
practically nontoxic
Over 15 g/kg
more than 1 quart
relatively harmless
The smaller the LD50, the more toxic the substance!
12
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-12
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
13
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-13
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
14
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-14
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
• Alcohol appears in blood within
minutes; 30–90 minutes for full
absorption
• Detoxification —about 90 percent in the
liver
15
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-15
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
16
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-16
Alcohol & Circulatory System
• Humans have a closed circulatory system
consisting of a heart, arteries, veins, and
capillaries.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-17
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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-18
Alcohol & Circulatory System
• Blood, carrying alcohol, moves to the heart and
is pumped to the lungs.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-19
Alcohol & Pulmonary 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-20
Breath Testers
• Breath testers that
operate on the
principle of infrared
light absorption are
becoming
increasingly popular
within the law
enforcement
community.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-21
Toxicology of Alcohol
• Like any depressant, alcohol principally affects
the central nervous system, particularly the
brain.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-22
Alcohol Levels
• After consumption, alcohol concentration
slowly decreases back to zero.
• 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-23
Alcohol Levels
• Elimination of alcohol throughout the body is
accomplished through oxidation and excretion.
• Oxidation is a chemical reaction that takes
place almost entirely in the liver
• Excretion of unchanged alcohol occurs 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 alcohol
content in the blood system (BAC) or by
measuring the alcohol content in the breath
(breathalyzer).
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-24
Alcohol Levels
• Experimental
evidence has
verified that the
amount of
alcohol exhaled
in the breath is
in direct
proportion to
the blood
alcohol
concentration
(BAC).
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-25
Alcohol and Law
• 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% w/v. It remains there today.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-26
Alcohol and Law
• To prevent a person’s 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-27
Breath Testers
• Many types of breath testers are designed to
analyze a set volume of breath.
• The captured breath is exposed to infrared
light.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-28
Breath Testers
• It’s 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-29
Field Testing
• Law enforcement officers typically use field
sobriety tests to estimate a motorist’s 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-30
Gas Chromatography Testing
• Gas chromatography offers the toxicologist the
most widely used approach for determining
alcohol levels in blood.
https://www.youtube.com/watch?v=4Xaa9WdXVTM
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-31
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 suspect’s 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.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-32
The Confirmation Step
• The GC (gas chromatography) separates the
sample into its components
• The MS (mass spectrometer) breaks the sample
into a unique “fingerprint” pattern that can be
used for identification.
https://www.youtube.com/watch?v=EzvQzImBuq8
• Once the drug is extracted and identified, the
toxicologist may be required to provide an
opinion on the drug’s effect on an individual’s
natural performance or physical state.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-33