Forensic Epidemiology of Poisoning Deaths in Nigeria: Patterns, Agents, and Investigative Frameworks

Poisoning deaths constitute a significant but systematically undercharacterised component of Nigeria's mortality burden, with forensic investigation capacity limitations contributing to chronic under-detection and misclassification. This doctoral study conducts a comprehensive forensic epidemiological investigation of poisoning deaths in Nigeria, developing original investigative frameworks for improving detection, attribution, and prevention. A multi-phase mixed-methods design was employed across five years, integrating retrospective analysis of 650 medico-legal death records from twelve states across all geopolitical zones, primary prospective data collection from 240 suspected poisoning admissions at twenty-two teaching hospitals, postmortem toxicological analysis of 180 specimens using multi-analyte GC-MS and LC-MS-MS panels, and expert panel synthesis. The study develops an original Nigerian Poisoning Forensic Classification System that categorises cases by intentionality, agent class, route of exposure, and investigation pathway. Findings reveal that pesticide poisoning accounts for forty-one percent of confirmed poisoning deaths, with organophosphate compounds predominating in North West and North Central agricultural zones. Traditional herbal toxins represent an under-recognised category, identified in eighteen percent of confirmed cases following extended analytical panels. The study demonstrates that standard autopsy-based investigation without dedicated toxicological screening misses forty-seven percent of confirmed poisoning deaths, providing empirical evidence for mandatory comprehensive toxicological protocols. Original contributions include the Poisoning Forensic Classification System, epidemiological mapping of geographic agent distribution, and evidence-based national poisoning investigation guidelines. Keywords: forensic epidemiology, poisoning deaths, toxicology, Nigeria, classification system.