Forensic Toxicology Overview

Forensic Toxicology and Pharmacology

• Forensic toxicologists analyze evidence to determine if toxins or drugs are present.
• Toxicology studies drugs, poisons, toxins, and metabolites (byproducts of drug breakdown).
• Poisons are natural or manufactured chemicals causing serious harm. (Examples: arsenic, rat poison)
• Toxins are poisonous substances produced by living things.
• Toxicologists develop specific tests and technologies to identify harmful substances in body fluids, stomach contents, or fluids from inside the eye.
• For deceased individuals, stomach contents, tissue samples from the liver and kidneys 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 reported poisoning victim.
• In 1600, arsenic was used as a poison.
• In the 1800s, Mathieu Orfila and Robert Christison developed methods to identify arsenic in tissues.
• In 1918, Charles Norris and Alexander Gettler developed standardizing techniques and testing to determine a cause of death.

Science of Toxicology (ADME)

• Absorption: Toxins enter the body via the digestive tract, lungs, skin, or bloodstream.
• Distribution: Chemicals travel through the circulatory system to various organs.
• Metabolism: Chemicals are broken down into metabolites and might be digested before absorption. The liver processes absorbed chemicals, and remaining toxins circulate throughout the body.
• Excretion: Kidneys excrete toxins via urine. Intestines eliminate via feces, sweat through skin, lungs via breath.

How Toxins and Drugs Affect the Body

• Acetaminophen destroys liver cells' ability to detoxify substances.
• Cyanide binds to hemoglobin, preventing oxygen uptake, leading to death.
• Fentanyl is more potent than heroin and affects respiratory control, resulting in fatal overdoses.
• Botulinum toxin (Botox) causes muscle paralysis.
• Cocaine increases blood pressure, leading to heart attacks or strokes.

Toxicity Factors

• Dosage (amount taken)
• Potency (drug's strength) - high potency drugs can be lethal in small amounts.

Duration and Nature of Exposure

• Duration: frequency and length of exposure.
• Nature of exposure: injected, inhaled, ingested, or absorbed through skin.
• Toxic metabolites: e.g., methanol's metabolite (formic acid) can cause blindness and death in small quantities.
• Indicators of poisoning: death with or without trauma, sudden unexpected death, unexplained recurring illness, similar unexplained symptoms at the same time as others, unexplained loss of consciousness.

Drug Addiction, Withdrawal, and Dependence

• Addiction involves feelings of pleasure from drug use that leads to physical dependence.
• Withdrawal occurs when drug use is reduced or discontinued, causing physical or mental symptoms.
• Drug dependence is characterized by craving without the withdrawal symptoms present in addiction.
• Drug tolerance occurs when a person needs increasingly larger amounts of a drug to feel the same effect.

Characteristics of Poisons, Toxins, and Drugs

• Heavy metals can enter via ingestion, inhalation, or skin absorption. They are stored in soft tissues and can damage organs. Arsenic contamination leads to gastrointestinal distress, difficulty speaking, muscle cramps, convulsions, kidney failure, and death.

Lesser Poisons

• Mercury exposure leads to skin lesions, headaches, and personality changes.
• Lead poisoning causes blue discoloration around the mouth, nausea, abdominal pain, and kidney problems.
• Potassium chloride affects the heart's ability to send electric signals.
• Sodium pentothal acts as a depressant, slowing down the CNS.
• Pesticides and herbicides (e.g., aldrin, dieldrin) can cause anxiety, rapid heartbeat, muscle weakness, and seizures.
• Glyphosate (a herbicide) can cause gastrointestinal problems, eye and skin irritation, kidney dysfunction, and death.

Drugs and Drug Schedules

• Schedule 1 drugs have no current medical use and a high potential for abuse. (Examples: heroin, LSD, MDMA, Marijuana)
• Schedule 2 drugs have a high potential for abuse and have medical use. (Examples: cocaine, fentanyl, methamphetamines, morphine, oxycodone)
• Schedule 3 drugs have a moderate potential for abuse and have medical use. (Examples: anabolic steroids, ketamine, Vicodin, Tylenol with codeine, testosterone)
• Other Schedules (Schedule 4, 5) have less potential for abuse.

Legal Drugs

• Hallucinogens (e.g., LSD, PCP) affect perception, thinking, self-awareness, emotions, and blood pressure and cause visual effects.

Methods of analysis

• Thin Layer Chromatography: separates compounds based on chemical affinity.
• Gas Chromatography: identifies and separates compounds, coupled by mass spectrometry for trace amounts in blood.
• Spectrometry analysis to find drugs and poisons.
• Color tests for drug presence

Evidence Processing and Packaging

• Collect evidence quickly (ASAP) as body processes break down drugs.
• Use PPE (personal protective equipment).
• Package samples with labels showing the date, time, and location of collection.
• Prevent mold and contamination.
• Dry wet items to avoid mold.
• Collect samples from the body and record and store them.

Forensic Analysis Techniques

• Preliminary testing (initial screening).
• Confirmatory testing for a definitive identification of drugs.
• Isolation, identification, and separation of individual drug/toxin ingredients.
• Quantitative testing for amount/concentration.