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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Was Paracelsus Right?
Hormesis —refers to the concept promoted by Paracelsus: that substances that kill at high doses are actually beneficial at low doses— the poison is in the dosage.
This appears to be true for many substances: oxygen, water, aspirin, alcohol, etc.
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5. Historical Perspective of Poisoners
Olympias—a famous Greek poisoner
Locusta—personal poisoner of Emperor Nero
Lucrezia Borgia—father was Pope Alexander VI
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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6. 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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Toxicology
Toxicology —the study of the adverse effects of chemicals or physical agents on living organisms.
Types:
Environmental Toxicology—air, water, soil
Consumer Toxicology—foods, cosmetics, drugs
Medical (Clinical) Toxicology—prescription medication
Forensic Toxicology —use of toxicology to aid in the investigation of death, poisoning and drug use.
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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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Toxins
Toxin—a substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with enzymes and receptors. (Usually a naturally produced substance that kills rapidly in small quantities)
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Toxic Substances
Toxic substances may:
Be a cause of death
Contribute to death
Cause impairment
Explain behavior
Poison hemlock is a plant
related to the carrot. It contains
alkaloids that negatively affect
the nervous system
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11. 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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Elements of Toxicity
Dosage
many substances are only lethal in high dosages
The chemical or physical form of the substance
Arsenic is not very poisonous in its natural form (metal); but arsenic trioxide or arsenic gas is very poisonous.
The mode of entry into the body
some substances are most poisonous if swallowed; others must be injected, inhaled or absorbed
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Elements of Toxicity
Body weight and physiological conditions of the victim, including age and sex
Blood alcohol content is directly related to body weight
Infants and elderly are more susceptible to most toxins
The time period of exposure
Sometimes small amounts ingested over time create a tolerance for the toxin
Chronic exposure (larger amounts over time) can create serious medical problems
Acute toxicity—very large dose causing immediate problems, including death
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Elements of Toxicity
The presence of other chemicals in the body or in the dose
Synergism: combination of two chemicals increases the effects of both in the system
Ex: antihistamine and alcohol
Antagonism: combination of two chemicals decreases the effects of both in the system
Ex: Chelating agent and arsenic
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Lethal Dose
LD50 —refers to the dose of a substance that kills half the test population, usually within four hours
(Note: test population is usually mice or rats)
Expressed in milligrams of substance per kilogram of body weight. A correlation is then made to humans based on the body weight data.
However, estimating lethal doses for humans is often complicated by the fact that resistance to certain chemicals can differ greatly between species
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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
mg/kg
to an ounce
moderately
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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LD50 Update
Because a single test may kill as many as 100 animals, the U.S. and other members of the Organization for Economic Cooperation and Development agreed in December 2000 to phase out the LD50 test in favor of alternatives that greatly reduce (or even eliminate) deaths of the test animals.
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18. Federal Regulatory Agencies
To ensure public safety, the federal government has created several regulatory agencies related to toxic substances:
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
Consumer Product Safety Commission—concerned with toxins in consumer products
Department of Transportation (DOT)—watches shipment of toxic chemicals
Occupational Safety and Health Administration (OSHA)—concerned with exposure to chemicals in the workplace
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19. 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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20. 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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23. 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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24. 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% is done in the liver at a rate of about 0.015% per hour.
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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26. BAC Blood Alcohol Content
Expressed as percent weight per volume of blood
Legal limits in all states is 0.08% (0.08 grams of pure alcohol for every 100ml of blood)
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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Sample Problem
What would be the approximate BAC of a 185 pound man who has consumed three shots (1.5 oz.each) of Jack Daniels (80 proof = 40% alcohol) in an hour?
BACmale = x 4.5 x 40 =
185
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Henry’s Law
Henry’s Law provides the scientific basis for the breath test check for sobriety.
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 2100 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
Invented in 1954
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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People in the News
John Trestrail is a practicing toxicologist who has consulted on many criminal poisoning cases. He is the founder of the Center for the Study of Criminal Poisoning in Grand Rapids, Michigan which has established an international database to receive and analyze reports of homicidal poisonings from around the world. He is also the director of DeVos Children’s Hospital Regional Poison Center. In addition, he wrote the book, Criminal Poisoning, used as a reference by law enforcement, forensic scientists and lawyers.
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More Information
Read more about Forensic Toxicology from Court TV’s Crime Library at:
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