engleski

Five-year toxicological study on Croatian brown bears

Environmental pollutants, both organic and inorganic, can have adverse effects on living organisms, as they persist in air, water, and soil and can accumulate in an individual and the food chain. The longevity, abundant food intake, and trophic position of brown bears (Ursus arctos) make this species a good bioindicator for pollution. Information gained through monitoring studies are relevant for humans residing in the monitored areas, those consuming bear's meat, as well as for the bear population, since the pollutants measured in bear tissue reflect the environmental load. Until now, the Dinara-Pindos bear population has not been studied with regard to toxic metals, organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs). Tissue sampling (muscle, liver, kidney cortex, fat) was undertaken from hunted and accidentally killed animals (roads, railways) between 2009 and 2013 according to the Brown Bear Management Plan for Croatia. Distribution of cadmium, lead, and mercury across the tissues of 371 bears was examined, as well as the impact of sex, age, and season on the respective metal levels. Seventeen PCB congeners and OCPs including hexachlorobenzene (HCB), hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites 1, 1-dichloro-2, 2-bis(p-dichlorodiphenyl)ethylene (DDE) and 1, 1-dichloro-2, 2-bis(p-chlorophenyl)ethane (DDD) were analysed in fat tissue of 32 bears. Female bears had higher cadmium and mercury tissue concentrations than male. The age-dependency of cadmium and lead in all of the bear tissues pointed to their accumulative property. Animals sampled in fall had higher muscle and hepatic mercury concentrations than the ones sampled in spring (Hg fall/spring: muscle 0.0033/0.0016 µg/g ; liver 0.053/0.028 µg/g wet mass). Among OCPs, the dominant compounds were gama-HCH and HCB followed by beta-HCH and DDE. PCB-153 and PCB-180 were the dominant congeners followed by PCB-138. In general, the measured concentrations of organic pollutants were low and differed between sexes. Regarding the maximum levels of cadmium and lead allowed in meat, liver and kidney for consumption, bear meat (median: Cd 0.0068, Pb 0.0040 µg/g wet mass) can be considered safe for human consumption but liver (median: Cd 0.954, Pb 0.424 µg/g wet mass) and kidney (median: Cd 14.1, Pb 0.972 µg/g wet mass) should be avoided.

brown bear ; toxic metals ; organochlorine pesticide ; polychlorinated biphenyl

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