A One Health framework integrating teratogenic risk and ecological assessment in freshwaters

Freshwater ecosystems face mixture-dominated pressures that often elude conventional monitoring. We assessed eight rivers in Latium (Central Italy) to jointly evaluate ecological status and teratogenic risk within a One Health perspective. We combined in-situ physico-chemical measurements and elemental profiling by inductively coupled plasma mass spectrometry (ICP-MS; including the rare-earth tracer gadolinium) with two biological lines of evidence: benthic diatom assemblages to derive the Intercalibration Common Metric Index (ICMi) and screen teratological valves, and the Hydra vulgaris regeneration assay summarized as the Teratogenic Risk Index (TRI), with behavioural endpoints. Environmental conditions were heterogeneous, with eutrophication and high organic load at some sites. ICMi classified Almone and Arrone as Poor, Marta and Sacco as Good, and Mignone, Aniene, Tevere and Ninfa as High. TRI indicated Very High teratogenic risk at Almone; High at Marta, Sacco and Tevere; Low at Arrone, Mignone and Aniene; and No risk at Ninfa. Diatom teratologies were detected at all sites and peaked at Tevere. ICMi showed a negative association with gadolinium (r = -0.76, p < 0.05), whereas TRI and ICMi were not correlated. These results demonstrate that ecological status and teratogenic hazard need not converge. TRI captured organism-level developmental and neuro-functional impairment at low doses and in complex mixtures, even where ICMi was Good/High. Integrating organism- and community-level indicators with targeted chemistry offers a sensitive, cost-effective framework to flag hotspots, prioritize monitoring of emerging contaminants, and support risk management under the Water Framework Directive.