Forensic Toxicology
and Alcohol
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Paracelsus
(1493-1541)
“What is there that is not a poison?
All things are poison and nothing
without poison. Solely the dose
determines that a thing is not a
poison.”
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What is Forensic Toxicology?
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Toxicology: Study of drugs and
poisons and their adverse affects
on the human system. Subfields
include:
pharmacokinetics (how the
drug works on people) and
pharmacodynamics (how
people work on the drugs)
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Drugs and Toxic Substances
•
•
•
•
Dose - amount of substance that enters the body
LD50 - Dose necessary to kill 1/2 of the population
Acute Toxicity - effects are immediate
Chronic Toxicity - effects occur over an extended
time
• Species Specific:
• Dioxin - polychlorinated organic compounds
(many)
– From burning chlorinated compounds
– Agent orange
– Paper industry
– Toxicity varies with species
Cl
O
Cl
Cl
O
Cl
Species LD50
Guinea Pig
Rabbit
Hamster
Monkey
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0.0006
0.115
3.5
0.07
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Toxic Substances
LD50 Calculations:
Cyanide (for 150 lb human - ~ 70 Kg)
(70Kg)(10mg/Kg) = 700 mg (0.70g)
Nicotine (e.g.; from Cigarettes)
(70Kg)(2 mg/Kg) = 140 mg (0.14g)
(note 1 cig. = ~ 2 mg Nicotine)
Ethanol
(70Kg)(1000mg/Kg) = 70,000mg (70g)
Substance
LD50
Aspirin
Ethanol
Morphine
Caffeine
Heroin
Lead
Cocaine
Cyanide
Nicotine
Strychnine
Batrachotoxin
1750
1000
500
200
150
20
17.5
10
2
0.8
0.002
Effect of Body Weight: Ethanol
150 lb Human = lethal dose = ~ 70 g
40 lb Dog = lethal dose = ~ 20 g
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MSDS Sheets
• Materials Safety Data Sheets - provide specific
toxicological, chemical and physical data about a
compound.
–
–
–
–
–
–
Physical Properties and Names
Chemical Reactivities
Incompatibilities
Safe Handling
Toxicology (symptoms and means of exposure)
Safety and First Aid
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MSDS Sheets - Example
NICOTINE
(S)-3-(1-Methylpyrrolidin-2-yl)pyridine
3-(1-Methyl-2-pyrrolidinyl)pyridine
b-Pyridyl-a-N-methylpyrrolidine
1-Methyl-2-(3-pyridyl)pyrrolidine
C10H14N2
CAS # 54-11-5
RTECS # QS5250000
ICSC # 0519
EC # 614-001-00-4
Molecular mass: 162.2
TYPES OF
HAZARD
ACUTE HAZARDS/
SYMPTOMS
PREVENTION
FIRE
Combustible. Gives off irritating
or toxic fumes (or gases) in a fire.
NO open flames.
EXPLOSION
EXPOSURE
INHALATION
SKIN
FIRST AID/
FIRE FIGHTING
Powder, alcohol-resistant
foam, water spray, carbon
dioxide.
Above 95°C explosive vapor/air
Above 95°C use a closed
mixtures may be formed.
system, ventilation.
PREVENT GENERATION OF MISTS! AVOID EXPOSURE OF (PREGNANT) WOMEN!
IN ALL CASES CONSULT A DOCTOR!
Burning sensation. Nausea. Vomiting.
Convulsions. Abdominal pain. Diarrhoea. Headache.
Sweating. Weakness. Dizziness. Confusion.
Ventilation, local exhaust, or breathing protection.
Fresh air, rest. Refer for medical attention.
MAY BE ABSORBED! Redness. Burning sensation
Protective gloves. Protective clothing. Remove contaminated clothes.
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Rinse and then wash skin with water and soap. Refer for medical attention.
Forensic Toxicological Questions
• Intentional or Accidental Poisoning?
• What type of Poison?
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– Corrosive Poisons - Substances that actually destroy
tissue outright
– Metabolic Poisons - Affect biochemical mechanisms.
• Drug Use - what drug, how much and when?
• Activity while under the influence of drugs?
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Common Terms
• Analyte - the compound that
you’re analyzing for.
• Metabolite - Compound
formed from the metabolism
of a drug. Heroin quickly
metabolizes to Morphine so
Morphine is a metabolite of
Heroin.
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Heroin
Morphine
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Journals
•
•
•
•
Journal of Analytical Toxicology
Journal of Forensic Science
Forensic Science International
Journal of Chromatography (B)
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• British Medical Journal
• Drug and Alcohol Dependence
• International Journal of Legal Medicine
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Specimen Collection
Each has it’s own set of problems and advantages
Fluids:
Organs:
Blood
Skin
Urine
Lungs
Vitreous Humor
Hair and Fingernails
Oral Fluid
Liver
Semen
Kidney
Stomach Contents
Bone
Bile
Other (heart, brain, etc.)
Vitreous Humor - clear, gel-like mass that fills the space between the lens and the retina.
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Sampling
• Blood - It matters where you sample in the body
– Blood taken near the liver or other solid organ may
contain drug that has diffused from the organ into the
blood post-mortem to give very high drug levels. Take
blood from femoral artery because it’s far from organs.
• Urine - tends to concentrate compounds.
– Can’t be sure of body concentration since it is unknown
how long it has been accumulating in the body.
• Liver - concentrates and stores drugs for long
times.
– good for detection but problematic for concentrations.
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Sampling
• Bile - Useful for detection but not concentration.
• Kidney - Similar to Bile.
• Vitreous Humor - Correlates well with femoral
blood for most compounds.
• Hair and Fingernails - Good for some compounds
with timelines possible.
• Oral Fluids - Can be easily disguised.
• Others - May be good for certain analyses but not
generally good sources for many compounds.
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Additional Matrices
Vomit
Earwax
Semen
Feces
Sweat
Meconium
Amniotic Fluid
Umbilical Cord Blood
Milk
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Specimen Collection:
Case Examples
• Deceased
– Suspected drug related death
– Road Traffic Death
– Murder
• Antecedent
–
–
–
–
Drink/drug driving
Drug Facilitated Sexual Assault (DFSA)
Professional/amateur athlete
Workplace drug testing
Dependent on the type of case and what samples are available
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Roles of Forensic Toxicology
• Postmortem Forensic Toxicology
• Human Performance Toxicology
• Forensic Drug Testing
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Postmortem Forensic
Toxicology
• Death Investigation
– Medical Examiners Office.
– NYS - elected corners or appointed Medical
Examiners depending upon county.
– Forensic Pathologist responsible for performing
autopsy.
– Forensic Toxicologist responsible for analyzing
biological samples for poisons.
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Specimen Collection
• Essential to collect the appropriate
specimens and that they are collected,
packaged, transported, and stored correctly.
• Pathologist is responsible for the collection
of the human-derived specimens and may
consult the toxicologist on unusual cases.
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Specimen Collection
• MOST IMPORTANT STEP!!!!
• Obtain a Representative Sample:
‘A small portion of a material taken from a bulk
specimen and selected in such a way that it
possesses the essential characteristics of the bulk’.
[E.g., easily possible to pick out a few crystals from
a sample that do not reflect the majority of the
sample - maybe that’s why they crystallized]
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Sample Handling
Storage
Avoid
- loss (due to volatility).
- contamination (e.g., insufficient seal).
Prevent
- chemical interactions (e.g., Na and oil).
- Degradation (refrigerate biological
samples).
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Sample Preparation
Homogenising - making the sample
uniform:
– grind (mortar and pestle)
– blender
– dissolution (water, solvents, acids)
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Postmortem
Forensic Toxicology
• Blood Samples
– Usually the most important
specimen
– Ideally 2 samples (25 mL
each)
– Femoral/jugular (peripheral
site) - far as possible from
solid organs
– Heart blood
– Trunk blood
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Postmortem Toxicology
• Vitreous humor samples - The clear, gel-like mass that
fills the space between the lens and the retina.
– Should be collected at all PM’s
– Relatively stable matrix
– Anatomically isolated area
– Good correlation with blood
– Easily obtained
Retina - The delicate lining at the back of the eye that functions much like the film in a
camera. It receives light through the lens in your eye, forms that light into images, and sends
those images to the brain, enabling you to see.
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Postmortem Toxicology
• Urine samples:
– All available sample should be
collected.
– Higher concentrations present
than in other matrices, but not
always.
– Rapid tests available (both
qualitative [what] and
quantitative [how much] tests).
– Not always available.
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Postmorten Toxicology
• Digestive System
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Postmortem Forensic
Toxicology
• Bile samples
– Alternative if urine unavailable
– Accumulation of drugs
– All available bile should
be collected
– Not an easy sample to analyze
Bile is a thick digestive fluid secreted by the liver and stored in the gallbladder. It
facilitates digestion by breaking down fats into fatty acids, which can be absorbed
by the digestive tract.
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Postmortem Forensic
Toxicology
• Liver samples:
Drug metabolism occurs in the liver.
Drugs may be present in higher concentrations.
Metabolite Analysis.
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Postmortem Forensic
Toxicology
• Other specimens:
– Lung (volatiles)
– Spleen (carbon monoxide) – blood unavailable
– Stomach Contents (drug overdose)
– Hair ( drug use history)
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Human Performance
Toxicology
• The effects of drugs on skills, acquisition,
learning, and performance.
• Drugs may alter normal behavior by either
enhancing or impairing performance.
• Stimulant drugs can enhance performance –
short term but used regularly can impair
performance.
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Human Performance
Toxicology
• Not only illicit drugs (e.g. heroin, cocaine,
cannabis, etc…
• Prescription medication can impair
performance especially at the start of the
treatment
– E.g. antidepressants, muscle relaxants, etc.
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Types of Abused Drugs
• Narcotics - relief from pain and bring sleep. (now
generally means a socially unacceptable drug).
– Narcotics are analgesic - relieve pain by depressing nervous
system (opium, morphine, heroin, codeine, opiates oxycontin, methadone).
• Hallucinogens - alter normal thoughts, perceptions and
moods (PCP, LSD, mescaline, MDMA, ecstasy).
• Depressants - depress functions of central nervous
system, cause calm and bring about sleep (alcohol,
barbituates). Tranquilizers are depressants.
• Stimulants - increase alertness and activity (cocaine,
amphetamines).
• Steroids - promote muscle growth (androgen,
testosterone, anabolic steroids).
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Types of Abused Drugs
• Narcotics - relief from pain and bring sleep. (now
generally means a socially unacceptable drug).
– Narcotics are analgesic - relieve pain by depressing nervous
system (opium, morphine, heroin, codeine, opiates - oxycontin,
methadone).
– Cocaine (stimulant), Marijuana
(hallucinogen), etc are Not classified
as narcotics even though they are
frequently called that.
– Most narcotics are opium derived.
– Opium from Poppy plants (sap is 4
21% opium).
Opium Poppy
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Hallucinogens
• Hallucinogens - alter normal thoughts, perceptions
and moods (PCP, LSD, mescaline, MDMA,
ecstasy).
• Marijuana most common (derived from Cannabis
or “hemp” plant).
– Derive resin from plant secretions that is extracted with
organic solvents.
– In use for 1000’s of years.
– Brought to the US ca. 1920.
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Stimulants and Depressants
1. Caffeine
2. Amphetamine
3. Cocaine
1.
2.
3.
4.
Labrium
Valium
Methaqualone
Ethyl Alcohol
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Steroids
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Steroids
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Human Performance
Toxicology
• Blood is the best specimen for determining
impairment through drugs.
– In contact with the central nervous system.
– Hair/urine/sweat – becoming popular but
unlikely that a quantitative relationship will
exist.
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Human Performance
Toxicology
• Alcohol and/or Drugs Involving Driving:
– In addition to collecting the correct samples,
additional information is essential:
•
•
•
•
Witness statements to the incident
Assessment of impairment at the scene
Field Sobriety tests
Drug Recognition Evaluation
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Forensic Drug Testing Where?
• Workplace Drug Testing
–
–
–
–
Armed forces
Prisons
Private and public companies
Schools
• International Olympic Committee
– Athletes
• Police Investigations
– Arrestee
– Drug Facilitated Sexual Assault (DFSA)
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Forensic Toxicology
• Sample Collection (uncontaminated)
• Specimen Identification (locate at crime scene)
• Storage
• Chain of Custody
• Analysis
• Reporting
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Forensic Toxicology
HOOCH2C
• Storage
–
–
–
–
–
Fridge/freezer
Preservative (EDTA in blood)
Leak proof
Suitable size
Prevent contamination
CH2COOH
N
N
CH2COOH
CH2COOH
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Forensic Toxicology
• Chain of Custody:
– Keeping tract of the control of the sample and
its handling from the time of collection until
analysis done.
– Very important to be admissible in court.
– Ensure procedures have been followed, seals
intact, signatures checked etc..
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Analytical Methods
• Qualitative Methods - What’s present?
– GC-MS - Mass Spectrometry
– Chemical Spot Tests - A test for a substance using reagents
that together generate an easily observed color or some other
physical change in the presence of the target substance. Spot tests
for blood, semen or certain drugs can be done at a crime scene,
but often the positive results are indicative only, and need more
sophisticated testing for court evidence.
• Quantitative Methods - How Much?
– Spectrophotometric Methods - Infrared, UV-Vis.,
Nuclear Magnetic Resonance (NMR), others.
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Forensic Analysis - GC
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Immunoassay
Immunoassay: A technique utilizing antibodies to bind
specifically to targeted substances in a specimen in
order to identify their presence.
Antibody - Protein produced by the immune system of
humans and higher animals in response to the presence of a
specific antigen.
Antigen - Substance that can trigger an immune response,
resulting in production of an antibody as part of the body's
defense against infection and disease. Many antigens are
foreign proteins (those not found naturally in the body). An
allergen is a special type of antigen which causes an
antibody response.
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Immunoassay
TWO METHODS
Immunoassay: A technique utilizing antibodies to bind
specifically to targeted substances in a specimen in
order to identify their presence.
EMIT - Enzyme Multiplied
Immunoassay Technique
A competitive binding
immunoassay that avoids
the separation step. As Test
antigen is increased it occupies more of
the antibody molecules, so fewer of the
enzyme labels are blocked. Substrate --->
product response increases.
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Immunoassay
TWO METHODS
Immunoassay: A technique utilizing antibodies to bind
specifically to targeted substances in a specimen in
order to identify their presence.
ELISA - Enzyme Linked
Immunosorbent Assay Wide application - diagnosis
& research.
Non-competitive "sandwich"
form requires two antibodyrecognition sites on test
antigen.
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Monoclonal Antibodies
• Polyclonal vs
Monoclonal
• Immortal
supply of antiprotein sera
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Confirmation/Quantitation
Validated Method with Detailed SOP
(Accepted Standard Operating Procedures)
Extraction Procedure
Chromatography
Gas and Liquid
Mass Spectrometry
Other Methods
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GC-MS
REF100
2020626
Scan EI+
TIC
1.67e7
31.73
100
33.71
42.18
19.17
%
46.23
53.91
41.44
42.98
47.20
0
Time
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
55.00
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Reporting:
•
•
•
•
Relationship of blood/urine alcohol
Levels of blood/tissue drugs
What do the metabolites indicate
Involvement of alcohol/drugs
Opiates
What do free/ total opiate levels indicate
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DRUGS
APPROXIMATE DETECTION TIMES OF SOME COMMON
DRUGS OF ABUSE IN URINE*
DURATION OF DETECTION IN URINE:
Alcohol
Amphetamines (including MDMA, MDA)
Barbiturates
Benzodiazepines
Cannabis
Cocaine
Codeine
Cyclizine
Dihydrocodeine
Heroin (morphine)
Methadone
6-MAM
up to 1 day
1-3 days
1-3 days
1-3 days
up to 14 days
1-3 days
1-2 days
1-2 days
1-2 days
up to 1 day
1-3 days
up to 1 day
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Alcohol
• No. 1 Abused drug with more related deaths per year
than any other.
• 5,000 to 10,000 year ago first prepared (guess).
• 700 BC the Greeks had a thriving wine industry, and
by 200 BC the Romans had developed the art of wine
making.
• Wine-making was concentrated around the warmer
Mediterranean lands, while beer was mostly
perfected in the cooler northern lands of Europe
where it was too cold to grow grapes.
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Alcohols
• Organic Alcohols (R-OH)
– Methanol CH3OH (wood alcohol)
• More toxic than ethanol LD50 = 428 mg/Kg
– Ethanol C2H5OH (grain alcohol, EtOH)
• Lethal Dose LD50 (LD to 50% of the people) =
7060 mg/kg of body weight
• Brain- CNS depressant
– Propanol C3H7OH (isopropyl alcohol, rubbing alcohol)
• More toxic than Ethanol (3600 mg/Kg)
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Ethanol
• Colorless liquid with a
burning taste and a
characteristic odour. Its RT
density is 0.785 g/ml, and its
boiling point is 78.4 C (F).
• Ethanol may be produced by
oxidation of ethylene gas or
fermentation of sugars.
• Ethyl alcohol can form
hydrogen-bonds and exhibits
intermolecular associations
the same manner as water.
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Ethanol
• Distilled alcohol always contains traces of water from the
distillation mixture (4 to 6%). To obtain 99%+ alcohol, the
water must be removed (unsuitable for consumption denatured).
• Ethanol dissolves both in water and in organic solvents.
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Ethanol Drinks
• Beverage alcohol is formed through fermentation of products
such as corn, potato mashes, fruit juices, and beet and cane
sugar molasses.
• Fermentation is an enzymatically controlled anaerobic
transformation of an organic compound - conversion of sugars
to ethanol by microscopic yeasts in the absence of oxygen (or
limited O2). The equation for the fermentation of glucose is:
C6H12O6 -----> 2CH3CH2OH + 2CO2
• Absorption of ethyl alcohol into the blood occurs mainly by
ingestion but also can occur through the skin and via the lungs.
• Alcohol quickly equilibrated through all body water.
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Beer
• Beer - produced from Barley steeped in water to
make it germinate (called Malt) - boiled with hops to
produce flavor and aroma. The resultant liquid (called
Wort) is then fermented. Various methods of
production after the fermentation stage, produce the
range of different beers we have today.
• Stronger beer is often referred to as Ale. Stout is
sweeter and is flavored with roasted grain. Lager is a
lighter beer that has been matured over a longer
period. “Lite” beer has less alcohol (But how Light it
Lite?).
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Beer
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Cider
• Cider comes from apples that are reduced to a pulp
which is then pressed to release the juice. This juice
is then placed into vats, often with yeast added, to
allow fermentation to take place. Sweet Cider is
filtered to stop fermentation before all the sugar has
been turned into alcohol. Traditional Sparkling Cider
is allowed to continue fermenting in the bottle,
although today, modern production methods mean
that Ciders often have the 'fizz' injected by
carbonation.
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Wine
• Made from Fermented Grapes:
– For red wines the skins are generally left in the
mix after the fruit has been crushed so that during
fermentation color from the skins seeps into the
juice.
– For white wines the skins are discarded after
crushing, and the grape solids are also removed
before fermentation.
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Other Alcoholic Drinks
• Brandy. Brandy is distilled wine made from grapes. Other fruit
based liquors can be used (must be clearly identified. E.g.: Cherry
Brandy). Brandy is aged in wooden casks until it is mature. Once it
has been bottled however, it ceases to mature.
• Gin. Made from malted barley and rye and usually flavored using
juniper and other botanicals. (Occasionally it is made from corn or
molasses).
• Rum. Distilled from fermented sugar cane. Traditionally, Rum has a
distinctive brown color, but Light Rum is also produced by rapid
fermentation.
• Whiskey or Whisky. Made from fermented grain. Fermentation is
started by adding yeast or the residue from previous fermentation
before distillation.
• Sherry. Sherry is a fortified wine in which Brandy has been added to
increase the alcohol content to 15.5% to 18%. [Sherry can only be
produced in the Jerez Region in the southern Spain, and any similar
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products made elsewhere must be called 'Fortified Wine’].
Ethanol Metabolism
• Ingested alcohol - down the esophagus - into the
stomach - into the small intestine.
• Most alcohol absorbed in the stomach (approx.
20%) and the small intestine (approx. 80%).
• More alcohol will result in increased blood
alcohol concentrations (BAC). A number of
factors can influence ethyl alcohol absorption
from the gastrointestinal tract.
– Gastric emptying - the faster gastric
emptying, the more rapid absorption. Food
delays gastric emptying and therefore delays
absorption of ethyl alcohol. The type of food
does not seem to be a factor. Physical exercise
also delays gastric emptying. Drugs (e.g.
nicotine, marijuana, and ginseng), may
modify physiological factors regulating
gastric emptying.
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Ethanol Metabolism
• Following ingestion, about 20% of the ethanol is
rapidly absorbed through the stomach wall. At first,
absorption is rapid but then the rate decreases even
if gastric concentrations remain high.
• Absorption of alcohol through the small intestine is
extremely rapid.
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Ethanol Metabolism
• After absorption, alcohol diffuses throughout the body
and is fairly uniformly distributed in all tissues and
fluids.
– Ethanol crosses the placenta and gains free
access to fetal circulation.
– It also crosses the blood brain barrier, thus the
CNS becomes an important target during alcohol
intoxication.
– Alcohol can affect many functions: the literature
shows pathological conditions on most body
organs from chronic consumption.
– Alcohol first affects front of brain then moves to
back (neurodepressant).
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Alcohol affects the brain front to back.
Alcohol and the Brain
Frontal LobeCognition and memory,
ability to concentrate,
judgment, inhibition,
personality and
emotional traits,
language, and motor
speech
Parietal Lobe - Ability
to discriminate between
sensory stimuli, ability
to locate and recognize
parts of the body,
disorientation of
environment space,
ability to write.
Occipital Lobe Primary visual
association area:
Allows for visual
interpretation.
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Alcohol affects the brain front to back.
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Alcohol “Flow”
Esophagus
Lungs, Urine
and Skin
Stomach
Body
Organs
Blood
Small Intestines
Liver for
Oxidation
•Concentration of alcohol in tissues depends
upon amount absorbed in blood.
•Direct relationship between amount of alcohol
excreted and blood alcohol levels.
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Ethanol Metabolism
• 90 to 98% of the ingested drug is completely oxidized (CO2 and H2O).
The small amounts that remain are excreted unchanged in the breath,
urine and sweat. This process occurs mainly in the liver:
• CH3--CH2--OH + NAD+ ---> CH3--CHO + NADH + H+
•
ethanol
acetaldehyde
• Blood levels fall some 0.015 % w/v
per hour (about 7.5 - 8.5
grams/hour) regardless of
initial alcohol concentration.
• Nothing you can do will speed this process
up...not exercising, vomiting, or drinking 30
glasses of espresso.
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% w/v is g per 100 mL
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Alcohol Effects
• Mild Intoxication (BAC = 0.050 %w/v) - Feeling of warmth,
skin flushed, impaired judgment, decreased inhibitions.
• Obvious Intoxication in most people (BAC = 0.100 %w/v) Increased impaired judgment, inhibition, attention, slowed
reflexes.
• Obvious Intoxication in all "normal" people (BAC = 0.150
%w/v) - General lack of muscle coordination, slurred speech,
double vision, memory and comprehension loss.
• Extreme intoxication (BAC = 0.250 %w/v) - Reduced
responsiveness, inability to stand, vomiting, incontinence,
sleepiness.
• Coma occurs around 0.350 %w/v and death is likely at 0.500
%w/v.
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% w/v is g per 100 mL
Alcohol Effects
• Alcohol’s action on the brain produces of a number of
behavioral effects. These effects are dependent upon the;
– 1. amount of alcohol taken in.
– 2. the time period over which the alcohol is drunk.
– 3. whether other drugs are being taken at the same time.
– 4. the previous drinking history of the individual.
– 5. the physical state of the person doing the drinking.
– 6. the genetic background of the individual( i.e. ethnicity,
gender).
– 7. the mood and psychological makeup of the individual.
– 8. the environment when alcohol is taken.
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Alcohol Effects
• “Hangover” Causes - 4 effects of ethanol:
– alcohol upsets your body's water balance. Causes “dry mouth” and
thirst.
– When alcohol is metabolized, it causes your blood to become more
acidic than normal (this is called acidosis). Causes nausea and
sweating.
– Alcohol alters the normal daily rhythm of certain body functions
(loose about 6 hours).
– Alcoholic drinks contain certain impurities called congeners which
can be toxic. [vodka and gin have few congenes and are supposed to
produce less of a hangover, whereas whisky and red wine, with lots of
cogeners, are supposed to insure a big headache. Also a toxic byproduct of
alcohol metabolism (acetaldehyde) builds in the bloodstream].
• Typical symptoms of hangover include nausea, ringing of the ears,
headache, increased heart rate, excessive thirst, anxiety, insomnia,
unsteadiness, dizziness (bed spins), diaphoresis (sweating), shakiness.
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Ethanol Testing
• Specimen Acquisition
– Breath Test (alcohol)
– Blood sample (alcohol and drugs)
– Urine sample (alcohol and drugs)
• Collection
– Breath – police officer at the scene
– Blood – must be obtained by a medic (forensic medical
examiner)
– Urine – collection must be observed
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Ethanol Testing
• FIELD SOBRIETY TESTING
– Portable, roadside breath tester.
– Walk and turn and/or one leg stand (divided attention
test).
– Horizontal gaze nystagmus- involuntary jerking of
eye as it moves to the side - more intoxicated the less
the eye moves before jerking.
• Breath Testing
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Ethanol Testing
• Breath Testing - direct relationship between BAC
and amount of alcohol vapor in breath.
– Henry’s Law - When a volatile compound is dissolved
in a liquid in equilibrium with the air, there is a fixed
ratio between the concentration of the volatile
compound in the air and its concentration in the liquid
(remains constant for a fixed temperature).
• When alcohol in blood is brought into equil. with
air (lungs), there is a fixed ratio between the
concentration of alcohol in air and the BAC.
• Measure the concentration of alcohol in air tells
the BAC quite reliably.
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Ethanol Testing
Breath Alcohol Testing: collects and measures alcohol content of
alveolar breath.
– Ratio of alcohol in the blood to alcohol in alveoli air is 2100
to 1 (1 mL of blood to 2100 mL of alveolar breath).
– Use Henry’s Law to determine BAC.
– Determines BAC in pulmonary artery. May not be the same
as venous blood but is most reflective of alcohol getting to
the brain.
– Sectrophotometer measures absorption of light through
potassium dichromate K2Cr2O7 .
– Alcohol reacts with dichromate so less dichromate means
more alcohol. Indirect Method.
– Some use infrared light to measure alcohol in chamber
78
directly. Direct Method.
CHE 113
Breathalyzer
•
Sample
Chamber
(52.5 mL)
•
•
Piston
Exhaled
Breath
3 mL of 0.025%
K2CrO4
•
•
Alcohol reacts with K2CrO4
to form acetic acid.
Amount of K2CrO4
consumed is related to
amount of alcohol present.
Spec. determination of
amount of K2CrO4
consumed.
Determine alcohol content in
sample.
Calculate BAC.
–Ratio of alcohol in the blood to alcohol in alveoli air is 2100 to 1 (1 mL of
blood to 2100 ml of alveolar breath). Alcohol in 52.5 mL of exhaled air is
equivalent amt. In 1/40 mL of blood.
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Breathalyzer
•
•
•
•
•
Alcohol reacts with K2CrO4
to form acetic acid.
Amount of K2CrO4
consumed is related to
amount of alcohol presnt.
Spec. determination of
amount of K2CrO4
consumed.
Determine alcohol content in
sample.
Calculate BAC.
–Silver nitrate is a catalyst
–Sulfuric acid removes alcohol from the air
–Reddish-orange dichromate ion changes color to the green chromium ion
when it reacts with the alcohol.
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CHE 113
Legal Aspects
• Motor Vehicle Operation is not a Federal issue (each state
determines).
– Although, federal law now has 0.08 %w/v as legal limit (states
must use or lose federal transportation funding).
• Blood Alcohol Content (BAC):
– 0.10% w/v = 0.10g EtOH/100 mL blood (most states for
limit under the influence).
– 0.08% is the NYS legal limit.
– 0.04 %w/v for commercial drivers.
• Canada, UK 0.05 %w/v.
• Sweden 0.02 5w/v.
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Legal Aspects
• Federal Law - driving on road gives “implied consent” for
testing (either take test or lose license).
• Schmerber v. California
– Pled 5th Amendment (not to self-incriminate).
– Supreme court ruled against him, stating the 5th
Amendment protects testimonial evidence not physical
evidence - therefore, he had to give his blood for testing.
– Ruled against Schmerber on Search and seizure stating that
blood sampling is an “emergency” procedure since by the
time a search warrant was obtained the BAC would have
dropped (destruction of evidence)
– Sample must be taken in a medically acceptable way without
unreasonable force and related to an accident or arrest.
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End of Toxicology
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