Wild terrestrial mammals as bioindicators of environmental pollution: biomonitoring of metals, rare earth elements and PFAS

Introduction: Environmental pollution is an increasingly relevant issue for wildlife health, ecosystem stability, and human health, particularly within a One Health framework. This research aimed to assess exposure to environmental contaminants in wild terrestrial mammals by using sentinel species and combining both invasive and non-invasive biological matrices. Materials and Methods: The first study examined liver and kidney samples from 30 crested porcupines collected in Central Italy between January 2020 and July 2025, with the aim of assessing the accumulation of potentially toxic metals and rare earth elements (REEs). Elemental concentrations were determined using quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Data distribution was evaluated using the Shapiro-Wilk test, while differences between tissues and sexes were analysed using the Mann-Whitney U test and the Kruskal-Wallis non-parametric test. The second study investigated PFAS contamination in hair samples from 58 wild terrestrial mammals exhibiting different feeding strategies. The animals were grouped into herbivores (roe deer and red deer; n = 23), omnivores (wild boar; n = 10), and predators (red fox, European badger, and wolf; n = 25). A total of 12 PFAS compounds were quantified using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Statistical analyses included the Shapiro-Wilk test to assess data normality and the Kruskal-Wallis test to evaluate differences among dietary groups. Results and Discussion: The first study showed that crested porcupines accumulated higher concentrations of cadmium and selenium in kidney tissue, whereas iron, zinc, and several rare earth elements were mainly concentrated in the liver. Sex-related differences were also detected for manganese and some hepatic REEs, suggesting potential biological variability in metal accumulation. In the PFAS study, contamination levels varied significantly depending on both the compound and the species analysed. Considering all hair samples, the highest mean concentrations were observed for PFNA and PFOA. Significant differences among trophic groups were also identified for several compounds. Predators showed significantly higher concentrations of L-PFOS and PFDoDA compared to herbivores, while omnivores also exhibited higher L-PFOS levels than herbivores. Additionally, PFUnDA concentrations were significantly higher in predators than in herbivores, supporting the occurrence of trophic transfer and biomagnification along the food chain. Overall, the findings confirm the value of wild terrestrial mammals as sentinel species for environmental biomonitoring. Moreover, the combined use of invasive (liver and kidney) and non-invasive (hair) matrices represents an effective approach to strengthen surveillance strategies and improve the assessment of environmental contamination within a One Health perspective.