1. Chapter 8 Toxicology: Poisons and Alcohol
“All substances are poisons. There is none which is not. The right dose differentiates a poison and remedy.”
—Paracelsus ( ). Swiss physician and chemist

2. Toxicology and Alcohol
Students will learn:
A quantitative approach to toxicology.
The danger of using alcohol.
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3. Toxicology and Alcohol
Students will be able to:
Discuss the connection of blood alcohol levels to the law, incapacity, and test results.
Understand the vocabulary of poisons.
Design and conduct scientific investigations.
Use technology and mathematics to improve investigations and communications.
Identify questions and concepts that guide scientific investigations.
Communicate and defend a scientific argument.
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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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7. Historical Perspective of Poisoners
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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8. 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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9. People of Historical Significance
Mathieu Orfila—known as the father of forensic toxicology, published in “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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Lethal Dose
LD50—refers to the dose of a substance that kills half the test population, usually within four hours
Expressed in milligrams of substance per kilogram of body weight
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Toxicity Classes
relatively harmless
more than 1 quart
Over 15g/kg
practically non-toxic
to a quart
5-15 g/kg
slightly
to a pint
mg/kg
moderately
to an ounce
mg/kg
highly
to a teaspoon
1-50 mg/kg
extremely
a taste to a drop
<1mg/kg
Toxicity
Correlation to Ingestion by 150 lb Adult Human
LD50 (rat,oral)
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13. Federal Regulatory Agencies
Food and Drug Administration (FDA)
Environmental Protection Agency (EPA)
Consumer Product Safety Commission
Department of Transportation (DOT)
Occupational Safety and Health Administration (OSHA)
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14. 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
Sulfuric acid Black vomit
Hydrochloric acid Greenish-brown vomit
Nitric acid Yellow vomit
Phosphorous Coffee brown vomit. Onion or garlic odor
Cyanide Burnt almond odor
Arsenic, Mercury Pronounced diarrhea
Methyl (wood) or Nausea and vomiting, unconsciousness,
Isopropyl (rubbing) alcohol possibly blindness
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15. Critical Information on Poisons
Common color
Characteristic odor
Solubility
Taste
Common sources
Lethal dose
Mechanism
Possible methods of administration
Time interval of onset of symptoms.
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
—John Trestrail from “Criminal Poisoning”
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To Prove a Case
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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18. Human Specimens for Analysis
Blood
Urine
Vitreous Humor of Eyes
Bile
Gastric contents
Liver tissue
Brain tissue
Kidney tissue
Hair/nails
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19. Alcohol—Ethyl Alcohol (C2H5OH)
Most abused drug in America
About 40% of all traffic deaths are alcohol-related
Toxic—affecting the central nervous system, especially the brain
Colorless liquid, generally diluted in water
Acts as a depressant
Alcohol appears in blood within minutes of consumption; minutes for full absorption
Detoxification—about 90% in the liver
About 5% is excreted unchanged in breath, perspiration and urine
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Rate of Absorption
Depends on:
amount of alcohol consumed
the alcohol content of the beverage
time taken to consume it
quantity and type of food present in the stomach
physiology of the consumer
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21. BAC Blood Alcohol Content
Expressed as percent weight per volume of blood
Legal limits in all states is 0.08%
Parameters influencing BAC:
Body weight
Alcoholic content
Number of beverages consumed
Time between consumption
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BAC
Burn off rate of 0.015% per hour but can vary:
Male
BAC male = x (oz) x (% alcohol)
body weight
Female
BAC female = x (oz) x (% alcohol)
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Henry’s Law
When a volatile chemical is dissolved in a liquid and is brought to equilibrium with air, there is a fixed ratio between the concentration of the volatile compound in the air and its concentration in the liquid; this ratio is constant for a given temperature. THEREFORE, the concentration of alcohol in breath is proportional to that in the blood.
This ratio of alcohol in the blood to alcohol in the alveolar air is approximately 2100 to 1. In other words 1 ml of blood will contain nearly the same amount of alcohol as ml of breath.
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Field Tests
Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another test is justified.
Psychophysical tests—3 Basic Tests
Horizontal gaze nystagmus (HGN): follow a pen or small flashlight, tracking left to right with one’s eyes. In general, wavering at 45 degrees indicates 0.10 BAC.
Nine Step walk and turn (WAT): comprehend and execute two or more simple instructions at one time.
One-leg stand (OLS): maintain balance, comprehend and execute two or more simple instructions at one time.
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The Breathalyzer
More practical in the field
Collects and measures alcohol content of alveolar breath
Breath sample mixes with 3 ml of % K2Cr2O7 in sulfuric acid and water
2K2Cr2O7 + 3C 2H5OH + 8H 2SO4  2Cr2(SO4) K2SO4 + 3CH3COOH + 11 H2O
Potassium dichromate is yellow, as concentration decreases its light absorption diminishes so the breathalyzer indirectly measures alcohol concentration by measuring light absorption of potassium dichromate before and after the reaction with alcohol
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Generalizations
During absorption, the concentration of alcohol in arterial blood will be higher than in venous blood.
Breath tests reflect alcohol concentration in the pulmonary artery.
The breathalyzer also can react with acetone (as found with diabetics), acetaldehyde, methanol, isopropyl alcohol, and paraldehyde, but these are toxic and their presence means the person is in serious medical condition.
Breathalyzers now use an infrared light absorption device with a digital read-out. Prints out a card for a permanent record.
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More Information
Read more about Forensic Toxicology from Court TV’s Crime Library at:
s/toxicology/2.html
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