Transcript forensic science - McEachern High School

FORENSIC SCIENCE
Introduction to Toxicology
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What is involved in Forensic
Toxicology?
Forensic toxicology helps determine:
a. The cause/effect relationships between exposure to a
drug or other substance
b. The toxic or lethal effects from that exposure
Toxicologists look for the presence of drugs &/or poisons
They use bodily fluids & organs
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What is involved in Forensic
Toxicology?
 Toxicologists
must understand metabolism
(transforming chemical in the body to
another chemical for the purpose of
elimination from the body)
 Reason: few substances enter and leave the
body in the same chemical state (think
digestion)
 Toxicology example: heroin breaks down to
morphine
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What is involved in Forensic
Toxicology?
 After
the toxicologist has detected,
identified and quantified (how much) a drug
or poison, they must also determine the
toxicity of the substance.
 Toxicity-how strong it is
 This is difficult since what is toxic to one
person may not be to another person
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What are techniques used in
toxicology?
 First-
selectively remove & isolate questioned
substance
 A large # of substances are isolated by using acids
and bases
 An acid is a compound capable of donating a
hydrogen ion
 A base is a compound that is capable of accepting a
hydrogen ion
 pH scale 0-6.9= acid and 7.1-14 = base; 7 is neutral
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What are techniques used in
toxicology?
 Testing
is in two parts: screening or
presumptive testing and then conclusive or
confirmative testing
 Screening/presumptive: done first; doesn’t
identify the substance, just tells you what it
MIGHT be; usually a color change test
 Conclusive/confirmative: done in lab;
identifies specific componenets
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Hmm.. Things to think about
 Less
than ½ to 1% of homicides result from
poisonings
 Accidental drug overdoses are more
common
 More than 50% of the federal prison
population and about 20% of the population
in state prisons consists of drug offenders
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Fastest way to get toxins to the
brain
The fastest way to get a drug
to the brain is by smoking
it. When a drug like tobacco
smoke is taken into the
lungs, nicotine seeps into the
lung blood where it can
quickly travel to the brain.
This is one reason why
smoking cigarettes is so
addicting is due to the fast
delivery
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Getting toxins to the brain

Injecting a drug directly into a
blood vessel is the second fastest
way to get a drug to the brain
followed by sniffing it through
the nose. The slowest mode of
delivery is by ingestion, such as
drinking alcohol. The effects of
alcohol take several minutes
rather than a few seconds to
cause behavioral & biological
changes in the brain
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What about drug dependence?
 Psychological
dependence: conditioned use
of drug caused by emotional needs
 Physical dependence: results in withdrawal
symptoms and sickness (ex: headaches
when caffeine is removed from diet until
body becomes used to its absence)
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Drug Lingo you need to be
familiar with
Speed
Cocaine Heroin
Crack
LSD
Cannabis
Ecstasy
Billy whiz Charge
Brown
Base
Acid
Blow
Adams
Crystal
Charlie
Gear
Pebbles
Rips
Dope
Dennis the
menace
Glass
Chaz
H
Rocks
Tabs
Ganga
Disco biscuits
CE
Coke
Horse
Scud
trips
Grass
E
Sulphate
Draw
Junk
lash
Hash
Love
uppers
Snow
Skag
weed
eves
toot
smack
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