Forensic Toxicology Basics

The scientific study and detection of drugs, alcohol, poisons, and other toxic substances in biological and related evidence for legal investigations.

To identify and evaluate potentially toxic substances and determine their possible contribution to the circumstances under investigation.

A substance capable of producing harmful biological effects under particular exposure conditions.

A poisonous substance produced by a living organism.

A toxin is biologically produced, while toxicant is a broader term encompassing harmful substances from various sources.

The magnitude or likelihood of a substance's effects generally depends on the dose and relevant exposure conditions.

Harmful effects resulting from a single exposure or exposures occurring over a relatively short period.

Harmful effects associated with repeated or prolonged exposure to a toxic substance.

The pathway through which a substance enters the body, such as ingestion, inhalation, injection, or skin absorption.

The movement of a substance from its exposure site into the bloodstream or systemic circulation.

The movement of a substance between blood and different tissues or compartments of the body.

The biochemical transformation of a substance into metabolites, often through enzymatic processes.

The elimination of a substance or its metabolites from the body.

Absorption, Distribution, Metabolism, and Excretion.

A compound formed when the body chemically transforms a drug or other substance.

It may provide evidence of exposure or metabolism, sometimes after the original substance is no longer readily detectable.

The time required for the amount or concentration of a substance in a defined biological system to decrease by approximately half under specified conditions.

No. Dose, metabolism, individual variation, distribution, and other factors limit precise timing estimates.

An initial examination used to identify possible substances or classes of substances requiring further analysis.

A more specific analytical procedure used to verify the identity of a substance detected or suspected during screening.

Gas chromatography-mass spectrometry.

To separate and identify suitable chemical compounds using chromatographic behavior and mass spectral information.

Liquid chromatography-tandem mass spectrometry.

It can provide sensitive and selective analysis of many drugs and metabolites in biological samples.

A test using antigen-antibody interactions to detect a substance or class of substances, subject to cross-reactivity and other limitations.

A reaction in which a test responds to a compound other than the primary target because of shared chemical or structural features.

Screening methods may produce false positives or lack sufficient specificity, requiring appropriate confirmation.

A result that fails to detect a substance that is actually present, potentially because of timing, concentration, method limitations, or other factors.

The period during which a substance or its metabolites may be detectable in a particular specimen using a specified method.

Substances and metabolites enter, persist in, and are eliminated from these specimens differently.

Blood concentrations may provide information more directly related to recent systemic exposure, subject to interpretation limitations.

Urine may reveal evidence of prior exposure through substances or metabolites excreted over a potentially longer period.

Urinary detection may continue after impairing effects have diminished or ended.

The gel-like fluid inside the eye that may be collected for certain postmortem chemical analyses.

It may be relatively protected from some postmortem changes and can assist selected biochemical or toxicological investigations.

The change in drug concentrations after death as substances move between tissues and body fluids.

A measured postmortem concentration may differ from the concentration present during life.

It may be less affected by some redistribution processes than central blood, although it is not immune to postmortem changes.

A substance of known identity and appropriate purity or concentration used to support analytical identification or measurement.

A relationship between known analyte concentrations and instrument responses used to estimate concentrations in unknown samples.

The lowest amount or concentration of an analyte that a method can reliably distinguish from the absence of the analyte under specified conditions.

The lowest concentration that can be measured with acceptable precision and accuracy under defined conditions.

The concentration of ethanol in blood, expressed using an appropriate unit or percentage.

It catalyzes the conversion of ethanol to acetaldehyde, primarily in the liver.

To help inhibit microbial activity and reduce certain changes that could affect alcohol analysis.

These details support identification, chain of custody, and interpretation of concentration and exposure timing.

The screening result alone does not establish confirmed detection; the analytical discrepancy must be evaluated.

Postmortem redistribution and other postmortem changes may affect the measured concentration.

No. Metabolite detection alone generally cannot determine the precise time of exposure.

The sample's identity and integrity may be challenged, undermining confidence in the analytical result.