Emil Srebočan

Malondialdehyde and heavy metal concentrations in tissues of wild boar (Sus scrofa L.) from central Croatia

The aim of this research was to assess the degree of heavy metal (cadmium, lead and mercury) contamination of wild boars from central Croatia and thereby conduct further tests to connect the contamination to oxidative stress occurrence. The highest cadmium concentration was noticed in the kidneys of older boars, the lead concentration was approximately the same in the liver and kidneys, but it was much higher than the concentration in the muscles, while the highest mercury concentration was measured in the kidneys of all wild boars. The correlation between the malondialdehyde (MDA) and the heavy metal concentrations was higher in tissue samples taken from younger animals (1 to 3 years of age) than in the tissue samples taken from older animals (5 to 6 years of age). In the kidneys of all wild boars there was a statistically significant connection between the MDA and cadmium concentration; in the kidneys of younger wild boars there was a statistically significant connection between the MDA and lead concentration. Further research on this topic should focus on MDA potential to find its use, not only as a contamination biomarker in the area of ecotoxicology, but also in the evaluation of the hygienic acceptability of animal products.

Mercury in hares organs (Lepus europaeus Pallas) in the vicinity of the mercury-contaminated natural gas treatment plant in Croatia.

In the last two decades (1990–2008), as part of a comprehensive monitoring of the eco-system, hares were collected in the vicinity of the mercury contaminated natural gas production and treatment plant Molve, Croatia. Their organs (muscle, liver, kidney and brain) were analyzed for total mercury concentration by cold vapor AAS. The range of the median mercury concentration values (wet weight) in hares organs were 0.001–0.005, 0.007–0.045, 0.022–0.126 and 0.0006–0.015 μg/g for muscle, liver, kidney and brain, respectively. The results of mercury measurements in hares organs during the period of last twenty years demonstrate a small but constant decline in concentration values. Comparing the results obtained in this study with results published in available data and literature on mercury concentration in hares tissue it can be concluded that area investigated in this research belongs to low mercury contaminated region. Nevertheless, further eco-monitoring and mercury measurements in various hares organs are valuable and necessary and will be continued.

Cadmium, lead and mercury concentrations in selected red deer (Cervus elaphus L.) tissues from north-eastern Croatia

Concentrations of cadmium, lead and mercury were determined in muscle, liver and kidney tissue from three different age groups of red deer (young animals aged 6 or 7 months, middle-aged animals aged 3 to 5 years, old animals aged over 8 years) from the Baranja region of Croatia. Median cadmium concentrations were low in the muscles of all investigated age groups (0.0002; 0.0009 and 0.0020 μg/g), higher in the liver (0.0279; 0.0656 and 0.1463 μg/g) and highest in the kidneys (0.4792; 2.8531 and 6.1657 μg/g). A positive correlation was established between cadmium concentration and age. In all analyzed tissues the median lead concentration was higher in young (muscle 0.0024; liver 0.0364 and kidney 0.0618 μg/g), compared to middle-aged animals (muscle 0.0001; liver 0.0184 and kidney 0.0160 μg/g). In contrast to cadmium, mercury had a negative correlation to age but median concentrations were very low (in muscle: 0.0011; 0.0001 and 0.0006 μg/g; in liver: 0.0051; 0.0037 and 0.0022 μg/g and in kidney: 0.0145; 0.0183 and 0.0106 μg/g) especially compared to cadmium. From the hygienic point of view all the examined tissues are edible since concentrations of the analyzed metals do not exceed values proposed by the official regulations, with the exception of a few kidney samples, which contained cadmium above the recommended value. Furthermore, mercury concentrations are no longer (since 2008) a matter of legislation.

A pathological condition possibly caused by spontaneous trichotecene poisoning in Brahma poultry: first report

Trichotecene poisoning in poultry can cause oral lesions, haemorrhages, depletion and necrosis in the lymphopoetic organs and death. Spontaneous poisonings with these toxins are rarely described. This paper describes the spontaneous poisoning of two Brahma chickens with T-2 toxin, diacetoxyscirpenol and deoxynivalenol. Two out of 10 chickens died under signs of depression and loss of appetite. Histopathological analysis revealed vacuolar dystrophy of the liver, necrosis and depletion of lymphocyte in the bursa of Fabricius as well as multiple necroses in the glandular stomach and gut. Even though quantities of 0.70 mg/kg T-2 in the food together with 0.50 mg/kg diacetoxyscirpenol significantly differ from the median lethal dose for chickens reported in literature (4.97 mg/kg), parasitological, virological and histopathological results indicate trichotecenes as the causative agents of this pathological condition.

Heat exposure and the toxicity of one number four lead shot in mallards, Anas platyrhynchos

Lead poisoning from ingested shot is a major cause of mortality in waterfowl throughout the world. In North America, most waterfowl that die from lead poisoning succumb following the hunting season. Cold and harsh winter weather is generally thought to exacerbate lead toxicity in birds. Although largely undocumented, there is considerable opportunity for birds to ingest lead shot in the summer during periods of extreme heat. Substantial lead exposure in over 50% of the American black ducks (Anas rubripes) captured in late summer has been observed in areas of the Chesapeake Bay. Moreover, investigations with rodents, rabbits, and man have demonstrated that the toxicity of lead is increased by high environmental temperature, possibly caused by elevated metabolic rate, dehydration, and impaired lead excretion. A recent study in which black ducks were dosed with a single number 4 lead shot suggested that toxicity may be enhanced during periods of extreme hot weather. To further investigate this finding, the authors examined lead toxicity in mallards maintained at thermoneutral temperature (21/sup 0/C) and at an elevated temperature (35/sup 0/C) approaching the upper critical limit.

Effects of mercury on glutathione and glutathione-dependent enzymes in hares (Lepus europaeus Pallas).

The aim of this study was to analyze and evaluate risks of long-term exposure to mercury in hares (Lepus europaeus Pallas), with a chemical-analytical approach evaluating median mass fraction of toxic mercury in the hares organs (liver, kidney, muscle and brain). To obtain better insight into possible effects of mercury, the study included screening of the oxidative status after long term exposure to low concentrations of mercury. Hares organs were analyzed for total mercury concentration by AAS. Glutathione and glutathione-dependent enzymes status was also investigated. The median mercury concentrations (wet weight) in the liver, kidney, muscle and brain of the hares ranged from 0.058–0.189, 0.138–0.406, 0.013–0.046 and 0.022–0.102 μg/g respectively. Concentration of the glutathione (GSH), glutathione-peroxidase (GPx), and glutathione-reductase (GR) activity increased with the mercury concentration. However, glutathione S-transferase (GST) and superoxide-dismutase (SOD) activity decreased with the mercury concentration. The results of this study show the impact of environmentally absorbed mercury on the antioxidant status of the examined hares. Further research on long-term exposure to low concentrations of mercury is needed.

Influence of cadmium on metallothionein expression and products of lipid peroxidation in the organs of hares (Lepus europaeus Pallas)

Cadmium occurs naturally in the environment and as an anthropogenic pollutant. Exposure to low concentrations of cadmium is inevitable and may produce toxic effects. Another important aspect of cadmium toxicity is its interaction, often antagonistic, with essential elements such as selenium. The aim of this study was to highlight the risks of long‐term exposure to low cadmium concentrations, using a scientific and chemical approach and hares (Lepus europaeus Pallas) as model organisms in a field study. Two study areas were monitored. Levels of cadmium and selenium were quantified in the organs of hares, the expression of metallothioneins I + II and the products of lipid peroxidation were determined. The median cadmium concentrations (wet weight) in the muscle, liver, kidney and brain of hares from an exposed group ranged from 0.033 to 0.037, 0.763 to 1.054, 3.090 to 16.594 and 0.016 to 0.087µg g−1, respectively; whereas, the median selenium concentrations (wet weight) ranged from 0.100 to 0.108, 0.153 to 0.332, 0.677 to 0.701 and 0.078 to 0.116µg g−1, respectively. Expression of the metallothioneins I + II proteins was observed in tissues. Lipid peroxidation (LPO) levels, measured as malondialdehyde (MDA) equivalents, increased with the cadmium concentration. Further research on long‐term exposure to low concentrations of cadmium in the environment is needed. Copyright

A case of a brown bear poisoning with carbofuran in Croatia

Abstract We provide the first known documentation of a fatal brown bear (Ursus arctos) poisoning with carbofuran (an acetylcholinesterase inhibitor) in Croatia. Diagnosis using liquid chromatography–mass spectrometry confirmed the presence of high concentrations of carbofuran in liver and kidney tissue (12.650 and 2.695 ppm, respectively). These measurements, combined with the very small distance between poisonous baits and the brown bear carcass, provided the basis on which we concluded that the animal consumed a lethal dose of carbofuran and succumbed to acute poisoning soon thereafter. We believe this mortality was caused by the illegal placement of this poison probably to eliminate perceived pests, such as jackals (Canis aureus) or foxes (Vulpes vulpes). Our documentation may help identify similar cases and raise awareness of the risks posed by illegal poisons for non-target species, particularly scavengers such as bears.

Mercury in pheasant (Phasianus colchicus) organs in Podravina, Croatia

Since 1995 the concentrations of total mercury were analyzed in the pheasant organs (liver, kidney, brain and muscle) that live freely in an area that was exposed to elevated levels of mercury as a result of industrial activity (mercury contaminated natural gas production and processing which began in 1980). The range of the median mercury concentration values (wet weight) in pheasant organs in Podravina, Croatia were 0.0004–0.024, 0.0001–0.034, 0.0002–0.016 and 0.0001–0.025 μg/g for liver, kidney, brain, and muscle, respectively. Results of these studies confirms that in the study area in the observed period there was no significant mercury contamination which can be linked to anthropogenic activities (hydrocarbon production)‥ On the contrary, systematic measurements demonstrate a small but constant (barely noticeable) decline in mercury concentrations in pheasants organs. Primarily, this is the result of the significant improvement in the technological process which involves the removal of mercury from the natural gas that was designed and implemented in 1993. However, due to the need for reliable control of mercury contaminated natural gas production and the importance for better understanding of long-term exposure to low levels of mercury, and assessment of their possible harmful effects on the environment, human and animal health, research will be continued.

Accumulated Metals and Metallothionein Expression in Organs of Hares (Lepus europaeus Pallas) Within Natural Gas Fields of Podravina, Croatia

Environmental impact of natural gas facility near Molve (Podravina, Croatia) was assessed using hares (Lepus europaeus Pallas) as biomonitors. Elevated levels of heavy metals in the environment lead to their accumulation in different tissues of hares. The authors have tested accumulation and distribution of several metals in hare liver, kidney, and muscle tissues. The accumulation of copper in hare liver and kidneys with concomitant decrease of zinc was observed in animals from Podravina region as opposed to the control group of animals (Island Krk, Croatia). Secondly, the expression of metallothioneins was assessed because of their crucial role in metal homeostasis. Observed elevation of metallothionein expression in tested organs emphasizes the possible prolonged negative effects of heavy metals in the surroundings as well as a state of oxidative stress in animals. Further monitoring of the area is necessary for better control of hydrocarbon processing to diminish the possible negative environmental effects.