Lead and Other Trace Element Levels in Brains of Croatian Large Terrestrial Carnivores: Influence of Biological and Ecological Factors

• Published in: Toxics (Basel) Vol. 11; no. 1; p. 4
• Main Authors: Lazarus, Maja, Sekovanić, Ankica, Reljić, Slaven, Kusak, Josip, Ferenčaković, Maja, Sindičić, Magda, Gomerčić, Tomislav, Huber, Đuro
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.12.2022; MDPI
• Subjects: Acids; Adults; Age; Animals; Arsenic; Bears; Brain; Brain stem; brown bear (Ursus arctos); Cadmium; Canis aureus; Canis lupus; Carnivores; Confounding (Statistics); Copper; Ecological effects; Enzymes; Eurasian lynx (Lynx lynx); Gene expression; golden jackal (Canis aureus); grey wolf (Canis lupus); Homeostasis; inorganic pollutants; Laboratory animals; Lead; Lead content; Liver; Lynx lynx; Mercury; Mercury (metal); metal(loid)s; Neurotoxicity; Oxidative stress; Pollutants; Predators; Proteins; Selenium; Trace elements; Ursus arctos; Wolves; Zinc; Croatia; apex predator; liver; Eurasian lynx (Lynx lynx); brown bear (Ursus arctos); golden jackal (Canis aureus); inorganic pollutants; metal(loid)s; grey wolf (Canis lupus)
• ISSN: 2305-6304; 2305-6304
• DOI: 10.3390/toxics11010004

Trace element pollution can adversely affect the brains of individuals and thus impact the entire population of apex predators, such as large European carnivores. We assessed exposure to prominent neurotoxicants As, Cd, Hg and Pb by measuring their brain stem levels in brown bears ( = 114), grey wolves ( = 8), Eurasian lynx ( = 3), and golden jackals ( = 2) sampled in 2015-2022 in Croatia. The highest of the non-essential elements was the Pb level in the bears' brains (median, Q1-Q3; 11.1, 7.13-24.1 μg/kg wet mass), with 4% of animals, all subadults, exceeding the established normal bovine levels (100 μg/kg wet mass). Species-specific differences were noted for Ca, Cd, Cu, Fe, Pb and Se brain levels. Female brown bears had higher As brain levels than males. Cubs and yearlings had lower brain Cd, but higher Zn, while subadults had higher Cu than adult bears. Hepatic As, Cd, Cu and Hg levels were shown to be a moderate proxy for estimating brain levels in bears (r = 0.30-0.69). Multiple associations of As, Cd, Hg and Pb with essential elements pointed to a possible interaction and disturbance of brain Ca, Cu, Fe, Se and Zn homeostasis. Non-essential element levels in the brains of four studied species were lower than reported earlier for terrestrial meso-carnivores and humans. The age and sex of animals were highlighted as essential factors in interpreting brain element levels in ecotoxicological studies of large carnivores.