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Drugs and Toxicology
Forensic Science
Ms MacCormack
Spring 2017
What is a drug?
A natural or synthetic substance that is used to
produce physiological or psychological effects
in humans.
75% of evidence evaluated in a crime lab is
drug-related!
What does drug dependency depend on?
The pattern and intensity of dependency on a
drug depends on:
Dose and route of administration.
Individual’s rate of metabolism
Frequency of administration
Classes of Drugs
1.Narcotics
2.Hallucinogens
3.Depressants
4.Stimulants
5.Anabolic Substances
Narcotics
 Reduce pain by suppressing the Central Nervous
System’s ability to relay pain messages to the brain – an
analgesic.
 Regular use will lead to physical dependence.
 Include Opium and its derivatives (morphine and heroin)
 Also includes Oxycodone, Methadone and codeine.
 Methadone has been used to lessen a person’s desire
for heroin.
Hallucinogens
Some are derived from plants while others
are man-made.
Affect the user’s perceptions, thinking,
self-awareness and emotions
Includes mescaline, marijuana, extracts
from mushrooms, LSD, Ecstasy, and PCP.
Marijuana
The most widely used illicit drug in the United
States today.
Effects of marijuana include
Increased heart rate
Reddening of the eyes
Dryness of the mouth
Increased appetite
Marijuana Continued….
Tetrahydrocannabinol, THC, is the
chemical found in marijuana that is
responsible for the hallucinogenic effects.
Use does not cause physical dependency
Heavy, long-term use can lead to
psychological dependence.
Medical Applications of Marijuana
Lessening of nausea caused by
anticancer drugs
Useful as a muscle relaxant
Reduction of excessive eye
pressure in glaucoma
Depressants
Drugs that relieve anxiety and produce
sleep
Reduce body functions such as heart rate.
Create a feeling of well being while
promoting relaxation
Depressants Continued
Act on the central nervous system and increases
the activity of a neurotransmitter called GABA.
Increased GABA causes drowsiness and slowed
brain activity.
Side effects include slurred speech, loss of
coordination and a state of intoxication.
Include alcohol, barbiturates, and tranqulizers
Alcohol
The most widely used and abused drug.
Low doses of alcohol inhibit the mental
processes of judgment, memory and
concentration.
Moderate doses of alcohol reduce coordination
substantially, inhibit orderly thought processes
and speech patterns and slow down reaction
times.
Alcohol continued….
Higher doses of alcohol may cause the
user to become highly irritable and
emotional.
Gas Chromatograph is often used by
forensic labs to analyze blood for alcohol.
Stimulants
 Increase feelings of energy and alertness while
suppressing appetite.
 Depression results as this drug wears off.
 Often used to boost endurance and productivity
 Highly addictive
 Examples include amphetamines, methamphetamines,
and cocaine
 Crack cocaine is the most difficult drug addiction
Depressants vs Stimulants
Anabolic Steroids
 Promote cell and tissue growth and division
 Produced in a lab and have a chemical structure similar
to that of testosterone.
 Originally used to treat hypogonadism – a condition in
which the testes produce an abnormally low level of
testosterone
 Used today to treat some cases of delayed puberty,
impotence and muscle wasting caused by HIV infection.
 Gained popularity in the 1930’s with weightlifters and
bodybuilders.
Anabolic Steroids
 Negative effects include:
Liver cancer and other liver malfunctions
Masculinizing effects on females
Infertility
Diminished sex drive in males
Premature halting of bone growth in teenagers
Unprovoked acts of anger and destructive behavior
Depression
Side Effects of Anabolic Steroids
Controlled Substances Act
Established five schedules of classification for
substances based on the drug’s:
Potential for abuse
Potential for physical and psychological
dependence
Medical value
Video Clips
 Collection of Evidence
 The Teen Files: The Truth About Drugs
Drug Identification
Screening Tests
A test that is nonspecific and preliminary in
nature.
This will reduce the possibilities to a small
manageable number.
Confirmation Tests
A single test that specifically identifies a
substance.
These tests include color tests,
microcrystalline tests, chromatography,
spectrophotometry and mass
spectrometry.
Color Tests
 Useful for screening purposes only!
 Marquis (2% formaldehyde in sulfuric acid)
 Turns purple in the presence of heroin and morphine and most
other opium derivatives.
 Turns orange brown in the presence of amphetamines and
methamphetamines.
 Dillie-Koppanyi
 Turns violet blue in the presence of barbituates
Color Tests
 Duquenois-Levine
Consists of three solutions
Test for marijuana
 Van Urk
Turns purple-blue in the presence of LSD
 Scott Test
Consists of two solutions
Tests for Cocaine
Microcyrstalline Tests
 More specific than color tests
 A drop of chemical reagent is added to a small quantity of the drug on a
microscope slide. A crystalline precipitate is produced a short time later.
Each drug has its own characteristic shape and size of crystals.
Chromatography
 Used in addition to color and crystal tests.
Mass Spectrometry
 Used in conjunction with Gas Chromatography.
 Gas Chromatography separates the mixture and then the mass
spectrometry is used produce a fragmentation pattern.
Toxicology
What is toxicology?
Concerned with the nature, effects and
detection of poisons.
Forensic toxicology is limited to matters
pertaining to violations of criminal laws.
Toxicology of Alcohol
Blood analysis is used to determine the quantity
of alcohol in a person’s system.
Blood is the means by which alcohol is
circulated through the body.
Blood alcohol concentration is directly
proportional to the concentration of alcohol in
the brain.
What determines the rate of alcohol
absorption?
 Total time taken to consume the drink
 Alcohol content of the beverage
 The amount consumed
 The quantity and type of food present in the stomach at
the time of consumption
How does the body eliminate alcohol?
 This is accomplished through two mechanisms:
 Oxidation
 Excretion
Oxidation
Oxidation – combination of oxygen with another
substance to produce new substances.
Alcohol + oxygen  Carbon Dioxide + Water
95 – 98% of all alcohol consumed is oxidized
Excretion
Remaining 2 – 5% is excreted unchanged in the
breath, urine and perspiration.
The amount of alcohol exhaled in the breath is
in direct proportion to the amount of alcohol in
the blood stream.
Closer look at the circulatory system
Humans have a closed circulatory system.
Made up of arteries, veins and capillaries
Artery – takes blood away from the heart
Vein – takes blood toward the heart
Capillary – connects arteries to veins
Alcohol in the Circulatory System
 Alcohol is ingested.
 Moves down the esophagus and into the stomach
 20% of the alcohol is absorbed through the stomach
walls and passes into the circulatory system.
 80% of the alcohol is absorbed into the circulatory
system in the small intestine.
 Alcohol travels to the liver where its destruction begins.
 Enters the heart and then goes to the lungs
Circulation of Alcohol
Travels to the lungs where it is oxygenated.
Blood travels back to the heart and then to the
rest of the body.
Alcohol then travels to all of the tissues of the
body.
Breath Test Instruments
 The Breathalyzer
 Collects and measures alcohol content of alveolar breath.
 This instrument is basically a spectrophotometer.
Field Sobriety Testing
 Preliminary tests
 Done to determine suspects degree of physical
impairment
 Consist of psychophysical tests and a breath-test
 Psychophysical testing could include:
Horizontal gaze nystagmus
Walk and turn
One-leg stand
Analysis of Blood for Alcohol
 Gas chromatograph is commonly used.
 Another procedure involves oxidation of alcohol to
acetaldehyde.
 Carried out in the presence of alcohol dehydrogenase
and NAD+
 Oxidation causes the NAD+ to be oxidized into NADH. This
conversion is measured spectrophotemetrically. The extent to
which this conversion happens is directly related to the amount
of alcohol present in the blood stream.
Collection and Preservation of Blood
for Alcohol Screening
Blood must be drawn under medically
accepted conditions by a qualified individual.
Non-alcoholic disinfectant must be used in
preparing the skin before the needle stick.
Blood is stored in an air tight container.
Anticoagulant and preservative are added to
prevent clotting and growth of bacteria that
could break down the alcohol.
Alcohol and the Law
 Most states have established a BAC of .08% to be the
cut off to be deemed as intoxicated.
 Implied Consent – When a person operates a motor
vehicle on a public highway, they automatically
consent to be subjected to taking a test for alcohol
intoxication or automatically lose their license for 6 a
designated time period (usually 1 year).
Schmerber vs. California
 Schmerber was arrested and charged with DUI while being
treated at a L.A. hospital for injuries sustained in an
automobile accident.
 Blood sample was taken by a physician as ordered by police.
Schmerber protested.
 Schmerber appealed to the US Supreme Court.
 Court ruled against him.
 Court noted the blood was taken in an emergency situation.
Had it been taken at a later time, the BAC would have been
declined thus destroying the evidence.