Animals as Sentinels of Environmental Toxicity in Italy: A Systematic Review of Epidemiological and Ecotoxicological Linkages under a One Health Framework

: The "Sentinel Hypothesis" posits that animals often manifest the effects of environmental pollution earlier than humans. This systematic review quantitatively validates this hypothesis within the One Health framework, focusing on three Italian National Interest Sites for Remediation (SINs): Taranto, Campania's "Terra dei Fuochi," and Sardinia. Adhering to PRISMA guidelines, we synthesized data from 76 studies (43 human epidemiological/biomonitoring outcomes, 33 animal sentinel outcomes). In Taranto, excess human cancer incidence (e.g., +40% liver cancer in men) correlates with severe dioxin contamination in the mussel Mytilus galloprovincialis (up to 14.88 pg WHO-TEQ/g). In Campania, polychlorinated biphenyls (PCBs) and dioxins detected in livestock products mirrored contamination found in human breast milk and elevated cancer mortality. In Sardinia, while human cancer epidemiology remains debated, lead accumulation in wild boar (Sus scrofa) liver (mean 6.70 mg/kg) aligns with elevated lead levels in children's hair, highlighting risks from both mining legacies and hunting ammunition. The findings confirm that veterinary surveillance data frequently precede human health alerts, documenting a "systematic delay" in public health response. We recommend integrating veterinary and human surveillance systems to operationalize animal sentinels as early warning tools for environmental health.