tox 1

Chapter 8

Toxicology:

Drugs and Poisons

“All substances are poisons. There is none which is not. The right dose differentiates a poison and remedy.”

—Paracelsus (1495-1541). Swiss physician and chemist

Toxicology

Definition—the study of the adverse effects

of chemicals or physical agents on living organisms.

Forensic Toxicology

 Postmortem—medical examiner or

coroner

 Criminal—motor vehicle accidents (MVA)

 Workplace—drug testing

 Sports—human and animal

 Environment—industrial, catastrophic,

Toxicology

Toxic substances may:

 Be a cause of death

 Contribute to death

 Cause impairment

Drugs

 A natural or synthetic substance designed to affect humans (or other animals)

 Drugs can be classified by their potential for

dependence:

Drugs

 Physiological Dependence:

-the body is exposed to a substance so frequently that it becomes reliant on the substance to function.

(Ex.Heroin)

- Experiences withdrawal symptoms such as

1. Sweating 2. Vomiting

3. Hallucinations 4. Seizures

Drugs

 Psychological Dependence:

- Frequent use of a substance leads the mind to rely on the substance to function (Ex. Cocaine, marijuana)

- Experiences withdrawal symptoms such as:

1. Depression 2. Irritability

Drug Classification

 Drugs are classified by their pharmacological effects (what they do to a person)

A. Hallucinogens B. Stimulants

C. Depressants

Drug Classification

A. Hallucinogens

Mostly naturally occurring substances that can change normal thought processes, perceptions, and moods

Hallucinogen Examples

 Marijuana- from the cannabis plant;

most widely used hallucinogen in the U.S

-decreases concentration, slows

reactions

 LSD (Acid)- chemically made from a

fungus on grain plants

Drug Classification

B. Stimulants

-Acts on the central nervous system -Increases energy, suppresses appetite -Causes anxiety and depression

Stimulant Examples

 Stimulants can range from coffee to

cocaine

 Cocaine- comes from the leaf of the coca plant; 500 pounds of leaves =

1 pound of cocaine

- Causes insomnia, weight loss

 Nicotine – found in tobacco

Drug Classifications

C. Depressants

-slows brain activity -Examples include:

 Anti-anxiety medications

 Sleeping Pills

 Alcohol

Drug Classifications

D. Narcotics (Analgesics)

- Substances that affect the central nervous system to relieve pain

- Narcotics are prescribed by doctors for pain but are often abused

Narcotic Examples

 Over the counter (OTC) - Aspirin, Tylenol,

Motrin

Narcotic Examples

 Opium- harvested from the poppy flower;

Contains morphine

 Heroine- made from morphine; injected

Poisons

 A substance that is capable of causing illness or death in humans and animals when

Poison Classification

 Poisons are classified as:

 1. Heavy metals  2. Corrosive  3. Pesticides  4. Toxins  5. Volatiles  6. Electrolytes

Heavy Metal Poisons

 Heavy Metal Poisons include:

 Arsenic

Poisoning--found in pesticides; causes brain and nerve damage

 Lead

Poisoning--found in old paint

-typical in occupational exposure (automotive repair, road construction)

Heavy Metal Poisons

 Heavy Metal Poisoning Symptoms:

 Vomiting, abdominal pain, diarrhea

Corrosive Poisons

 Corrosive Poisons include:

 Household Cleaners

Bleach

Drain cleaner

Ammonia

Corrosive Poisons

 Effects of corrosive poisons include:

-Burns to the skin, mouth, and throat

Pesticides

 Chemicals to control pest populations

 Pesticide poisoning symptoms include: Convulsions

Skin irritation

Toxins

 A harmful substance produced by a living

organism (plant or animal)

 Examples:

 Poison Arrow Dart Frog

 Blue Ring Octopus

Volatiles

 Gaseous substances that are harmful when

inhaled

 Examples include:

Electrolyte Poisoning

 An overabundance of minerals in the body causes adverse effects

 Can cause dizziness, vomiting, and kidney failure

 Electrolytes include: 1. Potassium

STOP HERE!

Detecting Poisons

 Detecting poisons in a corpse is an important step in determining if the death was a

Lethal Dose





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

50-500 mg/kg to an ounce moderately 500-5000 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

Detecting Poisons

 External Detection

 Poisons can be detected by looking at

physical changes in the corpse. (changes to

Detecting Poisons

 Examples:

 Arsenic-blue lines form under fingernails

 Carbon monoxide- turns skin bright pink

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

Detecting Poisons

 Internal Detection

 Poisons can be detected by testing various body

fluids and tissues.

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

Human Specimens for Analysis

Vitreous humor

Liquid in the eye that can be tested for

Fluid and Tissue Testing

 In order to determine what fluid or tissue is

tested for specific poisons the following must

be considered:

1. The site of administration (orally, inhaled, intravenously, dermal)

2. Which tissues have an attraction for the

substances (some poisons can affect ONLY

To Prove a Case

 Prove a crime was committed

 Motive

 Intent

 Access to poison

 Access to victim

 Death was caused by poison