Forensic Toxicology and Pharmacology Overview

Forensic Toxicology and Pharmacology

• Forensic Toxicologists analyze evidence to determine if toxins/drugs are present.
• Toxicology is the study of drugs, poisons, toxins, and metabolites (byproducts of the body breaking down drugs/poisons).
• Poisons are natural or manufactured chemicals that can cause serious harm (e.g., arsenic, rat poison).
• Toxins are naturally occurring poisonous substances produced by living things.
• Toxicologists use specific tests and technologies to identify harmful substances from body fluids, stomach contents, or fluids from inside the eye.
• If a person is deceased, stomach contents, tissues, liver, and kidney samples are examined.

History of Forensic Toxicology

• Paracelsus stated, "All substances are poisons; the right dose differentiates a poison from a remedy."
• Socrates was an early poisoning victim.
• In 1600, arsenic was used as a poison, highly toxic in small amounts, mimicking natural diseases.
• In the 1800s, Mathieu Orfila and Robert Christison developed chemical analysis methods to identify arsenic in tissues.
• In 1918, Charles Norris and Alexander Gettler established the first toxicology lab, standardizing techniques for determining cause of death.

Science of Toxicology - ADME

• Absorption: Chemicals enter the body through the digestive tract, lungs, bloodstream, or skin.
• Distribution: Chemicals travel through the circulatory system to the brain, liver, kidneys, and other parts of the body.
• Metabolism: The chemical is broken down into metabolites. If ingested, the chemical might be absorbed by the liver first. The liver only processes a limited amount before remaining toxin circulates throughout the body.
• Excretion: Chemicals leave the body through the kidneys (urine), intestines (feces), skin (sweat), and lungs (breath).

How Toxins and Drugs Affect the Body

• Examples of toxins/drugs and their effects on the body include acetaminophen (destroys liver cells), cyanide (inhibits oxygen to the body), fentanyl (affects respiratory control), botulinum toxin (causes muscle paralysis), cocaine (causes high blood pressure, heart attack, stroke), and various classes of stimulants, narcotics, depressants, and hallucinogens.
• Toxicity factors include dosage (amount taken), and potency (strength). High potency drugs can be lethal in small amounts.

Indicators of Poisoning

• Indicators of poisoning include unexpected death, unexplained illness that recurs in similar patterns, and sudden loss of consciousness.

Drug Addiction, Withdrawal, and Dependency

• Addiction involves feelings of pleasure produced by drugs, leading to a physical need for the drug.
• Withdrawal refers to physical/mental symptoms from reduced/discontinued drug use.
• Drug dependency is an intense craving for a drug without the withdrawal symptoms typically associated with addiction.
• Drug tolerance arises when a person needs to take more of a drug to feel the same effect.

Characteristics of Poisons, Toxins, Drugs

• Heavy metals (e.g., arsenic) enter the body through ingestion, inhalation, or skin absorption, are stored in soft tissues, and damage organs.
• Overexposure to Arsenic can lead to gastrointestinal symptoms, difficulty speaking, muscle cramps, convulsions, kidney failure, and death.
• Other substances, such as mercury, lead, potassium chloride, and sodium pentothal, have specific effects on the body.

Processing Evidence

• Drug-related evidence should be collected quickly (e.g., as soon as possible) as the body decomposes and breaks down drugs.
• Evidence detection methods include using dogs, chemicals, wadding for bags and hands, and examining containers.
• Ways to collect evidence include recovering Pills, Powders, Crystals found in food, paper, candy, seeds, leaves, mushrooms, Hair, Urine, samples, and stomach contents if deceased.

Evidence Packaging

• Evidence must be packaged and labeled (date and time) to prevent contamination/mold. Plant matter and wet items must be dried.

Forensic Analysis of Poisons, Toxins, Drugs

• Preliminary testing involves the use of field drug tests (color change).
• Confirmatory testing uses advanced techniques like chromatography and mass spectrometry for positive identification and quantification of substances.

Methods for Separating and Identifying Drugs/Toxins

• Thin layer chromatography (TLC) and Gas Chromatography (GC) separate components based on chemical affinities.
• Mass spectrometry is used with chromatography to identify molecules and their quantities.

Chemical Tests for Analysis

• Duquenois-Levine is a chemical test for cannabinoids (e.g., marijuana).

• Other tests are available to detect other toxins and drugs in samples.

Toxin/Pharmacokinetics vs. Toxic/Pharmacogenetics

• Pharmacokinetics studies how the body impacts drugs. Pharmacogenetics studies how genetics impact a person's response to drugs.
• Cutting agents are added to drugs to dilute them.
• Alkaloids are substances produced by plants and animals.

LD50 (Lethal Dose 50)

• LD50 is the amount of a substance required to kill 50% of a tested population.
• Different substances have different LD50 values.
• Some drugs are toxic when consumed at low doses.

Designer Drugs

• Designer drugs are synthesized and intended for abuse. They bypass drug law.