Toxicology: Poisons and Alcohol

Toxicology: Poisons and Alcohol

Objectives You will understand:

The danger of using alcohol.

A quantitative approach to toxicology.

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Toxicology: Poisons and Alcohol

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: Poisons and Alcohol

Toxicology

Toxicology

—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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Toxicology: Poisons and Alcohol

Forensic Toxicology

Postmortem

—medical examiner or coroner

Criminal

—motor vehicle accidents (MVA)

Workplace

—drug testing

Sports

—human and animal

Environment

—industrial, catastrophic, terrorism Chapter 8 Kendall/Hunt Publishing Company 5

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Toxicology: Poisons and Alcohol

Toxicology

Toxic substances may:

Be a cause of death Contribute to death Cause impairment Explain behavior Chapter 8 Kendall/Hunt Publishing Company 6

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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

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 Chapter 8 Kendall/Hunt Publishing Company 9

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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

Lethal Dose

LD 50 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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Toxicology: Poisons and Alcohol

Toxicity Classification

LD 50 (rat,oral)

<1 mg/kg 1 –50 mg/kg 50 –500 mg/kg 500 –5,000 mg/kg 5 –15 g/kg Over 15 g/kg

Correlation to Ingestion by 150-lb Adult Human

a taste to a drop to a teaspoon to an ounce to a pint to a quart more than 1 quart

Toxicity

extreme high moderate slight practically nontoxic relatively harmless Chapter 8 Kendall/Hunt Publishing Company 12

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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

Symptoms of Various Types of Poisoning

Type of Poison

Caustic poison (lye) Carbon monoxide Sulfuric acid Hydrochloric acid Nitric acid Phosphorus Cyanide Arsenic, mercury Methyl (wood) or isopropyl (rubbing) alcohol

Chapter 8

Symptom/Evidence

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 Kendall/Hunt Publishing Company 14

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Toxicology: Poisons and Alcohol

Critical Information

Form 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 Chapter 8 —John Trestrail from

Criminal Poisoning

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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

Alcohol —Ethyl Alcohol (C

2

H

5

OH)

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 Chapter 8 Kendall/Hunt Publishing Company 19

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Toxicology: Poisons and Alcohol

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 Chapter 8 Kendall/Hunt Publishing Company 20

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Toxicology: Poisons and Alcohol

BAC: Blood Alcohol Content

Expressed as percent weight per volume of blood Legal limit in all states is 0.08 percent Parameters influencing BAC:

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Toxicology: Poisons and Alcohol

BAC Calculation

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

BAC = 0.071  (oz)  (% alcohol) body weight

Female

BAC = 0.085  (oz)  (% alcohol) body weight Chapter 8 Kendall/Hunt Publishing Company 22

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Toxicology: Poisons and Alcohol

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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Toxicology: Poisons and Alcohol

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):

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Toxicology: Poisons and Alcohol

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 K 2 Cr 2 O 7 in sulfuric acid and water: 2K 2 Cr 2 O 7 +3C 2 H 5 OH + 8H 2 SO 4  2Cr 2 (SO 4 ) 3 + 2K 2 SO 4 + 3CH 3 COOH + 11H 2 O 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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Toxicology: Poisons and Alcohol

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/toxicol ogy/2.html

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