Oxamyl is a carbamate insecticide used to control a broad spectrum of insects. It can also affect non-targeted organisms when applied incorrectly. The world food production depends partially on honeybee pollination abilities and therefore it is directly linked to the health of bees. The success of the colony development depends, among other factors, on the health of the larvae. The first 6 days are crucial for their development. In this stage, the worker larvae grow exponentially and may be exposed to xenobiotics via their diet. In this study, we investigated the effect of oxamyl on honeybee larvae (Apis mellifera) by monitoring the changes in their antioxidant enzyme system. The activities of superoxide dismutase, catalase and glutathione-S-transferase were determined in the homogenates of in vitro reared honeybee larvae after their single dietary exposure to oxamyl at doses of 1.25, 2.5, 5, 10 and 20 µg a.i./larva (a. i.—active ingredient). The doses of oxamyl did not cause statistically significant changes in the activities of the enzymes. Even a slight activation of these enzymes protected the larvae from the adverse effects of the reactive oxygen species (ROS). Marked changes in both the enzyme activity and the content of lipid peroxidation products were observed at the oxamyl dose of 10 µg a. i./larva. This fact may indicate a potential oxidative damage to the larvae. These results allowed us to assume that the toxic effects of oxamyl involves not only the inhibition of acetylcholine esterase but is also associated with ROS production.
The quality of water in a well that serves as an individual drinking water source, located in the Slovakian region previously burdened with mining activities, was investigated in relation to the quality of surface water in the same region. Selected microbiological and physicochemical parameters were determined in samples of ground water (well) and surface water (brook and river). Plate counts of coliform bacteria, E. coli, enterococci and bacteria cultivated at 22 °C and 37 °C were determined. Microbiological quality of samples collected from the well was generally satisfactory. Examination of the samples of surface water (river) showed a significant organic pollution indicated by fluorescence spectra. In all water samples the values of: pH, electrical conductivity, dissolved oxygen, ammonium ions, nitrites, nitrates, chlorides and chemical oxygen demand (CODMn) were below the limits set by the state legislation. In the surface water, high levels of arsenic were found. The sum of calcium and magnesium in the well water was close to or below the recommended minimum level. In this well water, the level of antimony exceeded 10-fold the maximum limit for drinking water and was of the largest concern as this well water has been used for drinking, cooking, and watering of animals and vegetables for a long period of time. This poses a risk of accumulation of this metalloid in the food chain.