Toxicology Notes
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Transcript Toxicology Notes
Forensic Toxicology
Ch 5
pages 61-77
“All substances are poisons. There is none which
is not. The right dose differentiates a poison and
a remedy”
-Paracelsus (1495-1541)
Swiss physician and chemist
I. Introduction
Forensic toxicology
is the study of
poisons as they
pertain to legal
matters.
II. Applications of
Forensic Toxicology
3 main areas:
Postmortem Drug
testing
Workplace drug
testing
Investigation of
contraband materials
A. Postmortem Drug
Testing
Postmortem Drug
testing consists of a
death investigation with
a goal of establishing
whether drugs were the
cause or a contributing
factor.
Accidental or deliberate
overdose
B. Workplace Drug Testing
Workplace Drug
Testing consist of
the evaluation of
biofluids, (urine,
blood) from
employees or
applicants, for drug
content.
C. Investigation of
Contraband materials
Evaluation of
Contraband
materials is used to
identify prohibited
drugs.
Labs prove that
seized material is
illegal or not.
IV. Testing Process
Specimen Collection
1. Blood:
Is the most
important specimen
2 sample are taken;
from heart and then
peripheral site
Concentration of
toxins in blood is
more accurate than
any other fluid
2. Urine:
Is beneficial… b/c
large amounts can be
collected
Drug concentration
level is usually low
3. Gastric Contents:
Is beneficial in the case
of a deceased who has
ingested large amounts
of lethal agents
Usually in the case of
suicide
4. Hair:
Not common in
Forensic toxicology
investigations
because drugs in the
hair are extremely low
Can show passive
exposure
Can show a long term
exposure to drugs
5. Vitreous Humor:
Fluids from the eye
Is resistant to breakdown,
and takes a long time to
decay
Can also be used to
estimate time of death
6. Bile and Liver:
May contain significant
quantities of most drugs
because the liver is used in
metabolism of drugs
Drugs of Abuse
Drugs cited in the
National Laboratory
Certification Program
Amphetamines
Opiates
Phencyclidine
Cocaine
Cannabinoids
Amphetamines
Amphetamines and
methamphetamines
Stimulants that create an
excitable condition
characterized by an elevation
in heart rate, blood pressure,
and respiratory rate.
Cause intense euphoria
Include: ephedrine,
phenylpropanolamine,
phenylephrine,
Opiates
Opiates
Constitute a large class of
drugs distinguished by their
ability to cause profound
euphoria.
High potency pain relievers
Classified as depressants,
reduced muscle activity,
depressed respiration,
heartbeat, inclination to sleep
Grow in large amounts in Asia
Include; morphine, codeine, heroin,
OxyCotin, hydrocodone, oxycdone,
Phencyclidine
Phencyclidine
Aka. PCP, or peace pill
Originally intended for use as a surgical
anesthetic
Users show euphoria, feelings of
detachment, strength, power, severe
perceptual distortions, violent behavior,
psychosis, paranoia, and hallucinations
Cocaine
Cocaine
Is a stimulant that
resembles
amphetamine in its
abusive potential
Is a natural product
that include “free
base”, “crack”
Cannabinoids
Cannabinoids
The related psychoactive
compounds that come
from the plant Cannabis
Sativa.
Aka. Marijuana
Tetrahydrocannabibol
(THC) is the active agent
Drug state includes:
mood swings, euphoria,
perceptive alterations,
memory impairment, low
motivation
Analytical Methods in
Forensic Toxicology
1. The approach to testing for substances
has 2 parts:
screening
confirmation
Screening Tests
Immunoassays
– are tests in which
antibodies are used.
-they enable the
regents to react only
with a substance that
recognizes the
antibody.
Screening Tests
2. Thin Layer
Chromatography
(TLC) the specimen is extracted
into an organic solvent and
spotted onto a glass plate
coated with silica
the plate is placed into a tank
that separates whatever
chemicals were originally
present in the specimen.
Toxins are identified by the
distance they migrate up the
plate
Screening Tests
3. UV Visible
Spectrophotometry
most drugs absorb light
each drug produces a
characteristic spectrum
that allows the drug to
be identified because it
has peak absorbance at
a certain wavelength
Confirmation analysis
Gas Chromatography
is a method in which substances are separated from
other components of a mixture on a column
Gas Chromatography – Mass Spectrometry
is a combined method in which substances are
separated from other components of a mixture on a
column and a mass spectrum is also obtained
Bombarded with electrons
Interpreting Drug Findings
The goal of a forensic toxicologist in a
postmortem investigation is to collaborate
with the forensic pathologist in
determining the cause and manner of
death
Non medicinal Agents
Many deaths are due to chemicals that
are not medicinal and/or are encountered
in the environment.
Alcohol
Cyanide
Carbon Monoxide
Hydrocarbons
Heavy Metals
Alcohols
Ethanol is beverage alcohol
Enter the membranes of the nerve cells and
disrupt their normal architecture
Contributes to numerous disorders as a result
of a chronic abuser (Liver and brain)
Is usually measured by gas chromatography
Cyanide
Highly toxic substance found
in many forms
gas; hydrogen cyanide
solid: sodium cyanide
death occurs quickly
antidotes can save those
exposed to only small
amounts
Carbon monoxide
CO, prevents the transport of oxygen
Causes more deaths that any other toxic
substance
Present in fires, car exhaust
Hydrocarbons
Are commonly found in nature…..
Death is due to high exposure, or accident
following erratic behavior brought on by the
effects of hydrocarbons on the brain
Hydrocarbons can be gases (methane and
propane), liquids (hexane and benzene),
waxes or low melting solids (paraffin wax and
naphthalene) or polymers (polyethylene,
polypropylene and polystyrene).
Heavy Metals
individual metals and metal compounds that
negatively affect people's health.
in larger amounts, they become toxic. They
may build up in biological systems and become
a significant health hazard.
Arsenic
Beryllium
Lead
Mercury
Cadmium