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Toxicology: Poisons and Alcohol. Objectives. You will understand: The danger of using alcohol. A quantitative approach to toxicology. Objectives, continued. You will be able to: Discuss the connection of blood alcohol levels to the law, incapacity, and test results.

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Presentation Transcript

You will understand:

The danger of using alcohol.

A quantitative approach to toxicology.

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objectives continued
Objectives, continued

You 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—the study of the adverse effects of chemicals or physical agents on living organisms


Environmental—air, water, soil

Consumer—foods, cosmetics, drugs

Medical, clinical, forensic

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forensic toxicology
Forensic Toxicology

Postmortem—medical examiner

or coroner

Criminal—motor vehicle

accidents (MVA)

Workplace—drug testing

Sports—human and animal


catastrophic, terrorism

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Toxic substances may:

Be a cause of death

Contribute to death

Cause impairment

Explain behavior

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historical perspective of poisoners
Historical Perspective of Poisoners

Olympias—a famous Greek poisoner

Locusta—personal poisoner of Emperor Nero

Lucretia Borgia—father was Pope Alexander VI

Madame GiuliaToffana—committed over 600 successful poisonings, including two popes

HieronymaSpara—formed a society to teach women how to murder their husbands

Madame de Brinvilliers and CatherineDeshayes—French poisoners

AND many others through modern times.

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the severity of the problem
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
People of Historical Significance

Mathieu Orfila—known as the father of forensic toxicology, published in 1814 Traité 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
Aspects of Toxicity


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
Lethal Dose

LD50refers 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 classification
Toxicity Classification

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federal regulatory agencies
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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symptoms of various types of poisoning
Symptoms of Various Types of Poisoning

Type of Poison

Caustic poison (lye)

Carbon monoxide

Sulfuric acid

Hydrochloric acid

Nitric acid



Arsenic, mercury

Methyl (wood) or isopropyl

(rubbing) alcohol


Characteristic burns around the lips and

mouth of victim

Red or pink patches on the chest and

thigh, unusually bright red lividity

Black vomit

Greenish-brown vomit

Yellow vomit

Coffee-brown vomit, onion or garlic odor

Burnt almond odor

Extreme diarrhea

Nausea and vomiting, unconsciousness

possibly blindness

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critical information

Common color

Characteristic odor



Common sources

Lethal dose


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

Critical Information

—John Trestrail from Criminal Poisoning

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to prove a case
To Prove a Case

Prove a crime was committed



Access to poison

Access to victim

Death was homicidal

Death was caused by poison

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forensic autopsy
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


Vitreous humor of eyes


Gastric contents

Liver tissue

Brain tissue

Kidney tissue


Human Specimens for Analysis

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alcohol ethyl alcohol c 2 h 5 oh
Alcohol—Ethyl Alcohol (C2H5OH)

Most abused drug in America

About 40 percent 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; 30–90 minutes for full absorption

Detoxification—about 90 percent in the liver

About 5 percent is excreted unchanged in breath, perspiration, and urine

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rate of absorption
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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bac blood alcohol content
BAC: Blood Alcohol Content

Expressed as percent weight per volume of blood

Legal limit in all states is 0.08 percent

Parameters influencing BAC:

  • Body weight
  • Alcohol content
  • Number of beverages consumed
  • Time since consumption

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bac calculation
BAC Calculation

Burn-off rate of 0.015 percent per hour, but can vary:





0.071  (oz)  (% alcohol)

body weight

0.085  (oz)  (% alcohol)

body weight

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henry s law
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 2,100 to 1. In other words, 1 ml of blood will contain nearly the same amount of alcohol as 2,100 ml of breath.

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field tests
Field Tests

Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another test is justified

Psychophysical tests—three 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
The Breathalyzer

More practical in the field

Collects and measures alcohol content

of alveolar breath

Breath sample mixes with 3 ml of 0.025 percent K2Cr2O7 in sulfuric acid and water:

2K2Cr2O7 +3C2H5OH + 8H2SO42Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O

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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During absorption, the concentration of alcohol in arterial blood is higher than in venous blood.

Breath tests reflect alcohol concentration in the pulmonary artery.

The breathalyzer also can react with acetone (as found in 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 readout. Prints out a card for a permanent record.

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people in the news
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 personnel, forensic scientists, and lawyers.

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more information
More Information

Read more about forensic toxicology at truTV’s Crime Library:

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