Toxicology: Poisons and Alcohol

Kendall/Hunt Publishing Company2

Chapter 8


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Objectives

You will understand:

The danger of using alcohol.

A quantitative approach to

toxicology.


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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.

Objectives, continued


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Toxicology

Toxicology—the study of the adverse e ects 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

Olympias—a famous Greek poisoner

Locusta—personal poisoner of Emperor Nero

Lucretia Borgia—father was Pope Alexander VI

Madame Giulia To ana—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 Traité despoisons 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 Classification

relatively harmlessmore than 1 quartOver 15 g/kg

practically nontoxicto a quart5–15 g/kg

slightto a pint500–5,000 mg/kg

moderateto an ounce50–500 mg/kg

highto a teaspoon1–50 mg/kg

extremea taste to a drop<1 mg/kg

ToxicityCorrelation to Ingestion

by 150-lb Adult Human

LD50 (rat,oral)


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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

Symptom/EvidenceCharacteristic 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

Co ee-brown vomit, onion or garlic odor

Burnt almond odor

Extreme diarrhea

Nausea and vomiting, unconsciousness

possibly blindness

Type of PoisonCaustic poison (lye)

Carbon monoxide

Sulfuric acid

Hydrochloric acid

Nitric acid

Phosphorus

Cyanide

Arsenic, mercury

Methyl (wood) or isopropyl

(rubbing) alcohol


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Critical Information

Form

Common color

Characteristic odor

Solubility

Taste

Common sources

Lethal dose

Mechanism

Possible methods ofadministration

Time interval of onset ofsymptoms

Symptoms resulting from an acuteexposure

Symptoms resulting from chronicexposure

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 homicidal

Death was caused by poison


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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

Liver tissue

Brain tissue

Kidney tissue

Hair/nails


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Alcohol—Ethyl Alcohol (C2H5OH)

Most abused drug in America

About 40 percent of all tra c deaths are alcohol-related

Toxic—a ecting 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

Depends on:

Amount of alcohol consumed

The alcohol content ofthe beverage

Time taken to consume it

Quantity and type of foodpresent in the stomach

Physiology of the consumer


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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

Male

BAC =

Female

BAC =

Burn-o 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

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

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

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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Generalizations

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

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

Read more about forensic toxicology at truTV’s Crime

Library:

http://www.crimelibrary.com/criminal_mind/forensics/

toxicology/2.html

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