Toxicology

The expert can examine specimen type and collection, chain of custody, screening and confirmation methods, calibration and quality-control information, reporting thresholds, detected concentrations, and the interpretation attached to the result. A presumptive positive screening result indicates the possible presence of a substance and may require confirmation before analytical identification is established. Even after a substance is confirmed, separate analysis may be needed to determine what that finding supports about timing, impairment, exposure, or effect. Current forensic toxicology standards distinguish analytical identification and quantification from the later interpretation of results and emphasize method validation, specimen integrity, and appropriate reporting.

Toxic effects depend in part on the amount and conditions of exposure. Dose-response analysis examines how the likelihood or severity of an adverse effect changes with dose or concentration. The expert may consider route of exposure, duration, timing, susceptible populations, relevant study data, and uncertainty when determining whether published toxicological evidence applies to the circumstances being evaluated. EPA identifies dose-response assessment as a core component of human health risk assessment and distinguishes it from the separate questions of hazard identification and exposure assessment.