Recent research has revealed the need to investigate potential adverse effects, including temporal trends of persistent, bioaccumulative, and potentially toxic pollutants, particularly in top terrestrial mammals. This is essential in the One Health paradigm, which considers the interconnectedness of environmental, wildlife, and human health. Nevertheless, only a limited number of studies have been published in the past decade concerning metal(loid)-related effects on oxidative stress markers in wild terrestrial populations of predatory birds, reptiles, and small and large mammals. Due to their trophic ecology, brown bears are vital indicators of environmental health, shedding light on the risks of metal exposure for both wildlife and humans. This issue is especially relevant given climate change and shifts in wildlife dietary patterns, which may intensify the impact of pollution. Understanding these dynamics is crucial for more effective conservation efforts.
Given their role as primary excretory organs, the kidneys are particularly vulnerable to the accumulation of metals like cadmium (Cd) and lead (Pb). The study focused on understanding how these toxic elements impact oxidative balance and kidney health, while also exploring the influence of biological and environmental factors on metal accumulation. Our colleagues at the Institute for Medical Research and Occupational Safety and the Faculty of Veterinary Medicine in Zagreb, in collaboration with Dr. Agnieszka Sergiel and PhD student Joanna Macur, analyzed renal cortex samples (N =457) of free-ranging brown bears (Ursus arctos) from the Dinara-Pindos population. Toxic metal(loid)s concentrations were analysed and the underlying biological and environmental drivers of variation were addressed in this long-term study, spanning from 2009 to 2022. In 28 individuals sampled in 2021–2022, we investigated associations between metal(loid)s and oxidative stress and damage biomarkers in renal cortex cells. Non-specific toxicity thresholds for mammals were crossed in the case of Cd and Pb levels in 1–16% and 2% of individuals under study, respectively. These levels were higher than in sympatric carnivorous and herbivorous species but aligned with findings in ursids worldwide.
Moreover, both essential and non-essential metals were linked to changes in oxidative stress and damage markers in the kidneys of bears. Potential adverse health effects from environmental exposure may arise from disruption of oxidative balance, the severity of which is influenced by biological and environmental factors, such as season, age, sex, and body condition. More information on this study can be found here https://doi.org/10.1016/j.envpol.2024.125285
By Joanna Macur