Transcript Chapter 8

Chapter 8
Toxicology:
Poisons and Alcohol
“All substances are
poisons. There is
none which is not.
The right dose
differentiates a
poison and remedy.”
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—Paracelsus (1495-1541).
Swiss physician and
Toxicology
Definition—the study of the adverse effects
of chemicals or physical agents on living
organisms.
Types:
Environmental — air, water, soil
Consumer — foods, cosmetics, drugs
Medical, clinical, forensic
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Forensic Toxicology
 Postmortem—medical examiner or
coroner
 Criminal—motor vehicle accidents (MVA)
 Workplace—drug testing
 Sports—human and animal
 Environment—industrial, catastrophic,
terrorism
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Toxicology
Toxic substances may:
 Be a cause of death
 Contribute to death
 Cause impairment
 Explain behavior
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Historical Perspective
of Poisoners
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Olympias—a famous Greek poisoner
Locusta—personal poisoner of Emperor Nero
Lucretia Borgia—father was Pope Alexander VI
Madame Giulia Toffana—committed over 600
successful poisonings, including two Popes.
 Hieronyma Spara—formed a society to teach women
how to murder their husbands
 Madame de Brinvilliers and Catherine Deshayes—
French poisoners.
AND many others through modern times.
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The Severity of the Problem
“If all those buried in our cemeteries who
were poisoned could raise their hands,
we would probably be shocked by the
numbers.”
—John Harris Trestrail, “Criminal Poisoning”
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People of Historical Significance
Mathieu Orfila —
known as the father of
forensic toxicology,
published in 1814 “Traite
des Poisons” which
described the first
systematic approach to the
study of the chemistry and
physiological nature of
poisons.
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Aspects of Toxicity
 Dosage
 The chemical or physical form of the substance
 The mode of entry into the body
 Body weight and physiological conditions of the
victim, including age and sex
 The time period of exposure
 The presence of other chemicals in the body or
in the dose
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Aspects of Toxicity
The time period of exposure
 Chronic exposure
• Larger amounts spread out over a long
period of time
• Causes medical problems such as weakness,
sluggishness, hair & weight loss, mental instability,
and skin & liver cancer.
 Acute exposure
• Refers to a dose large enough to cause
immediate problems, including death.
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Aspects of Toxicity
The presence of other chemicals in the body or in
the dose or in the dose of the toxin:
 Synergism
• the combination of two chemicals increases their
individual effects
• ex: sedatives and alcohol
 Antagonism
• the combination of two chemicals decreases their
individual effects
• ex: some blood-pressure medicines and OTC cold
medicines with decongestants
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Lethal Dose
 LD50—refers to the dose of a substance
that kills half the test population (lab rats),
usually within four hours.
 Expressed in milligrams of substance per
kilogram of body weight
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Toxicity Classes
LD50 (rat,oral)
Correlation to Ingestion
by 150 lb Adult Human
Toxicity
<1mg/kg
a taste to a drop
extremely
1-50 mg/kg
to a teaspoon
highly
50-500 mg/kg
to an ounce
moderately
500-5000 mg/kg
to a pint
slightly
5-15 g/kg
to a quart
practically non-toxic
Over 15g/kg
more than 1 quart
relatively harmless
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Some Lethal Doses
Material
LD50, mg/kg, rats, oral
Sucrose (sugar)
29,700
Ethanol (ethyl alcohol)
7,060
Sodium chloride (table salt)
3,000
Caffeine
192
Sodium cyanide (spy novels –
poison capsules)
6.4
Ricin
0.020
Botulin toxin
0.000005 – 0.00005
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It’s All in the Dose?
 “All substances are
poisons. There is
none which is not.
The right dose
differentiates a poison
and remedy.”
 —Paracelsus (1495-1541).
Swiss physician and chemist
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Hormesis refers to
the concept that
substances that kill at
high dosages are
actually beneficial at
low dosages.
 Ex: botulin used to erase
wrinkles and ease
migraines.
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Federal Regulatory Agencies
 Food and Drug Administration (FDA) –
deals with pharmaceuticals, food additives,
and medical devices.
 Environmental Protection Agency (EPA)
– works with agricultural and industrial
chemicals released to the environment.
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Federal Regulatory Agencies
 Consumer Product Safety Commission
– concerned with toxins in consumer
products.
 Department of Transportation (DOT) –
watches over the shipment of toxic chemcials
 Occupational Safety and Health
Administration (OSHA) – is concerned with
exposure to chemicals in the workplace.
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Symptoms of Various Types
of Poisoning
Type of Poison
Symptom/Evidence
 Caustic Poison (lye)
Characteristic burns
around the lips and
mouth of the victim
 Carbon Monoxide
Red or pink patches
on the chest and
thighs, unusually
bright red lividity
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Symptoms of Various Types
of Poisoning
Type of Poison
Symptom/Evidence
 Sulfuric acid
 Hydrochloric acid
 Nitric acid
 Phosphorous
Black vomit
Greenish-brown vomit
Yellow vomit
Coffee-brown vomit;
onion or garlic odor
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Symptoms of Various Types
of Poisoning
Type of Poison
Symptom/Evidence
 Cyanide
 Arsenic, Mercury
 Methyl alcohol
Burnt almond odor
Pronounced diarrhea
Nausea & vomiting,
unconsciousness
aka wood alcohol
 Isopropyl alcohol
Possibly blindness
aka rubbing alcohol
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Critical Information on Poisons
—John Trestrail from “Criminal Poisoning”
 Form
 Common color
 Characteristic odor
 Solubility
 Taste
 Common sources
 Lethal dose
 Mechanism
 Possible methods of administration
 Time interval of onset of symptoms.
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Critical Information on Poisons
—John Trestrail from “Criminal Poisoning”
 Symptoms resulting from an acute exposure
 Symptoms resulting from chronic exposure
 Disease states mimicked by poisoning
 Notes relating to the victim
 Specimens from victim
 Analytical detection methods
 Known toxic levels
 Notes pertinent to analysis of poison
 List of cases in which poison was used
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To Prove a Case
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Prove a crime was committed
Motive
Intent
Access to poison
Access to victim
Death was caused by poison
Death was homicidal
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Forensic Autopsy
Look for:
 Irritated tissues
 Characteristic odors
 Mees lines—single transverse white bands on nails.
Order toxicological screens
 Postmortem concentrations should be done at the
scene for comparison
 No realistic calculation of dose can be made from a
single measurement
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Human Specimens for Analysis
 Blood
 Urine
 Vitreous Humor of
Eyes
 Bile
 Gastric contents
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 Liver tissue
 Brain tissue
 Kidney tissue
 Hair/nails
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