Forensic Implications of the Gut Microbiome Shaped by Environmental Toxicants

Environmental toxicants pervade air, water, soil, and food, complicating causal attribution in pollution-related deaths and intoxications. This review outlines two complementary evidentiary domains: The relatively stable ante-mortem gut microbiome, which encodes exposure history, and the highly dynamic postmortem thanatomicrobiome, whose rapid succession and translocation may obscure premortem signals. We summarize current evidence that microbial metabolism reshapes toxicokinetics through hydrolysis, reduction, and deconjugation, thereby reactivating conjugates within the enterohepatic cycle and altering exposure windows, dose–response relationships, and target-organ delivery. Conversely, heavy metals, persistent organic pollutants, pesticides, antibiotics, and therapeutic drugs can remodel microbial communities, impair epithelial integrity, and disrupt the bile acid–short-chain fatty acid axis, generating functional biomarkers of forensic value. Analytical recommendations include parallel untargeted/targeted mass spectrometry, quantitative profiling of conjugated – free – reactivated pairs, molecularly imprinted polymer enrichment, and time-sensitive sampling with enzymatic inhibition to preserve postmortem metabolic spectra. Finally, the Daubert/Frye admissibility frameworks are evaluated with respect to validation, known error rates, and protocol standardization, emphasizing a shift from correlative to functionally anchored interpretations. Collectively, this framework integrates microbiota–toxin–host interactions with forensic practice, enhancing causal inference in environmental and drug-related investigations.