Toxicology: Drugs and Poisons Forensic Science

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Toxicology: Drugs and Poisons
Forensic Science
Toxicology
Toxicology - Mix of Chemistry and Physiology
that deals with drugs, poisons, and other toxic
substances.
– Began in 1775 when Swedish chemist Karl Scheele
discovered a way to prove arsenic was the culprit in
a suspicious death.
Poisons
• ANY substance that when taken in sufficient
quantities causes a harmful or deadly reaction.
(Sufficient quantities – how much enters the body, over what
period of time)
1. Intoxicant requires an ingestion of large quantities
before it is lethal
- Ex: Carbon Monoxide, Alcohol, heavy metals (mercury,
lead, selenium)
2. True Poison – requires only a tiny amount
- Ex: Cyanide
The Forensic Toxicologist
• Finds toxins and determines the
likely effect on the individual who
ingested or came in contact with it.
• Examples:
– Inebriation in an automobile accident or
industrial accident
– Whether a person died from poison or from
natural cause?
– Whether drugs played a role in a perpetrator’s
actions or in seizures or coma?
Effects of Toxins
• Effects of toxins do not cause VISIBLE changes in
the body in living people or during an autopsy.
• Medical Examiner will collect fluids and tissues for
testing
– Toxins are sneaky! Biotransformation can change
one chemical into another within the body due to
metabolism.
– The toxicologist may have to look for a
different sign of the toxin.
– Ex: Heroin will change into morphine
in the bloodstream so looking for heroin is
fruitless
Best Places for Sample Testing
Blood – most useful… tells what is going on at the time of
death.
2. Urine – Easily obtained… Urine can’t determine whether a
drug was exerting any effect at time it was collected.
3. Stomach Contents – survivors are sampled by way of a
gastric tube. Still no correlation between effects at time it was
collected but will determine if in the body
4. Liver – important in metabolism (destruction) of undesirables
in the body. Many drugs concentrate in the liver, so no signs
may be in the blood but the liver will reveal if
a toxin is present.
- Amounts in liver determine hours before
death
- Amount in bile determines past 3-4 days of exposure
1.
Sampling Continued…
5. Vitreous Humor – EYE BALL WATER… resists
decay…may be the only fluid left in a decaying body…
levels in this fluid lag behind the blood levels by 1 to 2
hours.
6. Hair – absorbs heavy metals and provides
timeline of ingestion… can determine if a
poisoning was quick (acute) or drawn out
(chromic)
- Arsenic will kill whether given all at once or slowly
administered
7. Insects – that feed on the corpse will have elevated
levels of certain drugs and may provide
information if the drug was present at death.
Common Testing Procedures
1. Color Tests – a reagent is added to the substance
to be tested and a color change will represent the
presence of the suspected chemical.
-
CHEAP, EASY, and QUICK
2. Immunoassays – Antigen-antibody
reaction… substance being sought
is the antigen-testing reagent is the
antibody.
-
An antibody will react only with antigens
and ignores all other chemicals
Testing Procedures
Continued…
3. Gas Chromatography – Separates compounds according to
size, shapes, and chemical properties… will determine class
of compounds but not exact makeup
- can be used to separate a large mixed sample for further
analysis
4. Ultra-Violet Spectroscopy – different compounds absorb and
reflect light differently… indicates the concentration of a drug
in a sample
5. Mass Spectrometry (MS) – high energy bombards the
sample and breaks it into tiny fragments. They are passed
through a magnetic field and separated by molecular
weight…Produces the same pattern… can be used to ID.
Points of Administration
• Toxins will be most concentrated at the point of entry:
a. Ingested Toxins – show up more in the stomach, intestines,
and liver
b. Inhaled Toxins – show up in the lungs
c. Injected Toxins – linger in tissues around point
of injection… muscle slows down the transfer
to the bloodstream.
d. Intravenously (IV) – will bypass the stomach
and liver going directly into the bloodstream
therefore quickly distributed… very little remains in the IV
site.
• May find high concentrations in tissues but none in
stomach or intestines.
Testing Continued…
• Once testing is done, the toxicologist
evaluates what toxins are present, identifying
routes of administration, and determining
whether the concentration is sufficient to play
a role in the subject’s death or behavior.
• Route of entry is EXTREMELY important
in cases of injection where the person had no
means to inject or no physical capabilities…
homicide is a stronger consideration.
Be Aware…
• Finding a large quantity of toxin in the
stomach does not meant it is the cause of
death!
• The toxin may not have entered the
bloodstream yet. Blood concentration is
the MOST important!
Concentration Categories by the
Toxicologist
Normal – expected in the general population under normal
circumstances
2. Therapeutic – The level your doctor wants in
your bloodstream for medical reasons
3. Toxic – a level that may cause harm- nausea,
vomiting, change in heart rhythm
4. Lethal – Level at which the toxin consistently cause death
– LD50 – means the toxin at that level will cause 50% of
people to die.
•
Wiggle room between categories – everyone reacts
differently based on age, sex, body size, genetics, and
health.
1.
Responsibilities of the Toxicologist
1. Know the chemical make-up,
physiological actions, and byproducts of the drug
2. Understand how the drug is
metabolized by the body and
the potential of the metabolites
3. Know how the chemicals will
effect healthy people and people
with various illnesses and
addictions.
4. Recognize the symptoms and signs
produced by the chemicals.
Familiar Poisons
• Cyanide – very lethal
–
–
–
–
Can enter by inhalation, ingestion, or direct skin contact
Used for executions
Damages internal workings of the cell
ME will notice a BRIGHT cherry red color to the victim’s blood.
• Strychnine – plant based rat poison
–
–
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Extremely bitter taste: hard to disguise
Causes a LOT of pain: Not typical in suicides
Causes convulsions
Death is caused by asphyxia
Rigor mortis is quick because of the depletion of ATP during
convulsions
• Mushrooms – easily confused with the edible type
– Implicated in accidental suicides and homicides
– Causes severe damage to liver and extremely low
blood sugar level
Poisons Continued…
• Ethylene Glycol – antifreeze
– Alcoholics sometimes will consume it to satisfy the urge to
drink
– Causes deadly breakdown of oxalic acid reacting with
calcium in the blood and crystallizes in the brain and kidneys
– ME will find crystals in tubules of kidney
• Oxalic Acid – raw rhubarb
– Powerful irritant to gastrointestinal track
– May cause bleeding
– ME will find irritation of mouth, esophagus, stomach, and low levels of
calcium in the blood
• Heavy Metals – Arsenic, Mercury, Lead, Antimony, Bismusth, Thallium
– All behave slightly different but cause gastrointestinal injury
– Leads to nausea, vomiting, diarrhea (bloody)
– Damages kidneys, liver, brain, and nerves
More Poisons…
• Insulin – drops blood sugar level
– Robs brain of nutrients: death is quick
– If the ME finds high levels of insulin he will look for
a tumor in the pancreas to rule out natural death
– If there is NO tumor… suspects homicide
• Succinyl Choline – injectable drug
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–
–
–
paralyzes all the muscles of the body
Lethal injections
Leaves behind little evidence of presence
ME looks for metabolites
• Corrosive Chemicals – Strong alkalis bases (lye) and acids
– When ingested…corrode and burn tissues of digestive track
– Causes bleeding, shock, and death
– Rarely used in homicides…mostly accidental children ingestion.
Case Study – Carl Coppolino
Physician Anesthesiologist
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August 1965
Carl called his friend Dr. Karow to report that his wife had died.
She signed the death certificate and no autopsy was preformed.
Carl had been having an affair with a neighbor. When the affair ended, she
went to Dr. Karow with her story.
She had been given a syringe and Coppolino had instructed her on how to kill
her husband, so they could continue the affair. She did not go through with it,
but Coppolino came and strangled her husband and signed the death
certificate.
Investigations and autopsies were preformed – Coppolino was acquitted in
the death of the husband.
However, the ME knew that Coppolino had access to succinyl choline and
that this drug would not be present in the corpse but the metabolite succinic
acid would be.
Large quantities were found and Coppolino was convicted of 2nd degree
murder of his wife.
Common Drugs
• Categorized by physiological and
psychological effects.
• Can effect structure and/or function
of tissues via chemical reactions
• Legal or illegal
• Addictive (Narcotics) or non-addictive
• Drugs covered by law are “controlled substances” and
taken in excess may cause death or illness.
• 75% of evidence analyzed is drug-related
• Pharmaceutical companies send samples of new drugs
to the FBI to be categorized for future comparisons
Depressants
• Make you sleepy and lethargic
• Considered downers
– Ex: Alcohol
• most commonly abused drug
• Suppresses respiration - potentially lethal + addictive
• Blood levels correlate to degree of intoxication
– Ex: Opiates
• Derived from poppies
• Sleep producing and produces euphoria
and lethargy
– Barbiturates - sleeping pills
Stimulants
• Increases alertness
• Lessens fatigue – suppresses appetite
• Irritability, anxiousness, aggressive behavior,
paranoia, fatigue, depression
• The body will get use to the drug and require
more for an effect, so the person is taking ever
increasing doses
• HIGHLY
ADDICTIVE!
• Ex: Amphetamines,
Cocaine
Other Drugs
• Hallucinogens
– Alter perception and mood
– Leads to delusional thinking and hallucinations.
– Ex: Marijuana, cacti, mushrooms, LSD, PCP,
Ecstasy, Rohyphonol (Date rate drug)
• Narcotics
– Pain reducers
– Ex: morphine, methadone, codeine,
heroin
• Anabolic Steroids
– Increase testosterone
– Aggressive behavior and diminished sex drive
– Liver cancer

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