Postmortem Toxicology Study Notes

Postmortem Toxicology: Death Investigation & Toxicology

Introduction to Toxicology

• Toxicology: The study of the adverse effects of chemicals on biological systems.

Branches of Toxicology

• Analytical Toxicology: Techniques and methods for detecting toxic substances.

• Applied Toxicology: Application of toxicology principles in practical situations.

• Clinical Toxicology: Focused on diagnosing and treating poisoning in patients.

• Forensic Toxicology: Analyzing substances related to legal investigations, especially in postmortem cases.

• Environmental Toxicology: Effects of chemicals on the environment and wildlife.

• Reproductive and Developmental Toxicology: Assessment of the effects of substances on reproduction and development.

• Immunotoxicology: Study of toxic substances that affect the immune system.

Postmortem Toxicology and Forensics

• Two General Branches in Forensics:

  1. Postmortem Toxicology: Analysis of biological samples (e.g., blood, tissue) for drugs, poisons, and metabolites.

  2. Seized Drugs Analysis: Collection and characterization of physical evidence (e.g., pills and powders).

Goals of Postmortem Toxicology

• Key questions addressed include:

  1. What was taken?

  2. When was it taken?

  3. How much was taken?

  4. Did this substance contribute to the cause of death?

• The results help to determine:

  1. Manner of death: Circumstances surrounding the death.

  2. Mechanism of death: The physiological process that leads to death.

Contents of Post-Mortem Report

• Identification: Name of the deceased.

• Post-mortem Details: Place, date, and time of the postmortem examination.

• Examinations:

  • External Examination: Physical examination of the body.

  • Internal Examination: Detailed assessment of internal organs.

• Viscera and Samples: Collection of tissue samples for toxicological analysis.

• Opinions: As to cause and manner of death.

Important Definitions

• Xenobiotic: Substances that are foreign to the body, including all types of chemicals, not just poisons.

• Drug: Any compound that produces a physiological effect on the body.

• Poison: A substance that produces harmful effects when ingested, referred to as toxins in this context.

Historical Context of Poisoning

• Lex Cornelia (82 AD): The first known legal response to poisoning enacted by Roman dictator Lucius Cornelius Sulla.

• Historical figures associated with poison:

  • Guilia Tofana: Known for creating a poison for women to use against abusive husbands.

  • Lucrezia Borgia: Often linked with infamous tales of poison use in political maneuvering.

  • Arsenic Trioxide: Known historically as a potent poison frequently associated with murder.

Arsenic Poisoning in History

• Mary Anne Cotton: Dubbed the "Angel of Death" due to her use of arsenic to murder family members for insurance claims.

• Napoleon Bonaparte: Hypothesized to have died from arsenic poisoning; linked to green wallpaper in his prison cell.

  • Post-mortem investigations suggested arsenic exposure.

Contributions of Early Forensic Chemistry

• Dr. Mathieu Orfila (1787-1853): Considered the father of forensic toxicology, known for studying arsenic and contributing to the establishment of toxicology as a science.

• Marsh Test:

  • A method developed to detect arsenic in biological samples.

  • Involves chemical reactions producing arsine gas and detecting arsenic through deposits in a glass apparatus.

Mechanism of the Marsh Test

1. A sample is placed in a flask with arsenic-free zinc and sulfuric gas.

2. Arsine gas is produced, alongside hydrogen.

3. This gas travels through a drying tube into a heated glass container.

4. Arsenic is deposited as a black “mirror” in the container.

Understanding Arsenic

• Arsenic can bond with various elements (Hydrogen, Oxygen, Carbon) creating different compounds.

• Covalent Bond: A strong bond formed when atoms share electrons.

• The Dose Makes the Poison: Arsenic, while toxic, is also used in industry and medicine (e.g., cancer treatment).

Degrees of Toxicity

• Factors influencing toxicity include:

  • Mode of ingestion

  • Identification, measurement, & location of metabolites

  • Body weight and fat percentage

  • Individual metabolism

• Toxic versus Therapeutic Dose:

  • Recommended adult dose: $4 ext{ grams/day} = 4000 ext{ mg}$.

  • Children: $90 ext{ mg/kg/day}$; for an average 2-year-old weighing $12 ext{ kg}$, the maximum is $1,080 ext{ mg}$.

Discussions of Drug Toxicity

• Common poisonous substances:

  • Plutonium, Botulism, Nerve Gas, Mercury, and Arsenic.

• Carfentanil: A highly potent synthetic opioid; a mere few micrograms can be lethal.

Opiates and Their Effects

• Opiates: Derived from the opium poppy; include substances such as Heroin.

  • Overdose rates have increased due to the rise in synthetic opiates.

• Naloxone (NARCAN): A medication used to reverse opioid overdose effects.

Pharmacokinetics – ADME

• ADME stands for:

  • Administration

  • Distribution

  • Metabolism

  • Excretion

• Understanding how drugs are processed in the body is crucial for toxicology.

First Pass Effect

• Definition: The process where drugs absorbed from the gastrointestinal tract first pass through the liver via the portal vein, leading to potential metabolism before reaching systemic circulation.

• Consequences: Drugs with high first-pass metabolism have lower bioavailability.

Distribution and Excretion

• Volume of Distribution (V): Drugs can distribute into various bodily compartments:

  • Plasma (4 liters)

  • Interstitial Fluid (10 liters)

  • Intracellular Fluid (28 liters)

• Excretion Pathways: Include kidneys, lungs, and bilary excretion through urine or feces.

Toxicity and Impact on the Body

• Understanding how a substance behaves chemically and physiologically in the body helps forensic scientists determine its impact on cause of death.

Effects of Drugs on Dopamine Release

• Various drugs affect dopamine levels significantly, enhancing the brain's pleasure centers, influencing natural reward pathways.

• Examples include Amphetamine and Cocaine, which show dramatically increased dopamine release compared to baseline levels.

Common Specimens for Postmortem Toxicology Analysis

Sample Collection: Vitreous Humor

• The vitreous humor from the eye is often reliable for toxicology due to its anatomical isolation, allowing it to be useful in decomposition scenarios.

Biological evidence, such as blood and tissue samples, helps forensic scientists, specifically forensic toxicologists, by allowing them to analyze for drugs, poisons, and their metabolites. This analysis helps answer critical questions like: What substances were taken, when were they taken, how much was consumed, and if they contributed to the cause of death. Ultimately, these findings are essential in determining both the manner and mechanism of death.