Assessment of intracellular accumulation of cadmium and thallium.

The aim of the study was to develop fast and accurate method for assessment of intracellular level of cadmium (Cd) and thallium (Tl), and to establish accumulation of the metals in the cells. HepG2 cells were treated with Cd or Tl (1.0 or 10.0 mg/L; 24 h) and level of Cd or Tl was assessed. ICP-MS was applied and the method was optimized and validated. Correlation coefficient (R2) for Cd was 0.9999 with intercept 0.0732 while for Tl was 1.00009 with intercept -0.1497, and limit of detection (LOD) for Cd was 0.020 µg/L and for Tl 0.097 µg/L. Both metals, Cd and Tl, accumulate in the cells in concentration-dependent manner. However, higher uptake of Cd in comparison to Tl was observed. Cells treated with the same concentration of the metal (1.0 mg/L) accumulated 10.0% of Cd and 1.0% of Tl. Higher uptake of Cd than Tl can explain higher toxicity of Cd toward HepG2 cells. Obtained results imply to the importance of monitoring the level of metals in the cells in order to connect changes at the molecular level with exposure to specific metal.

Assessment of acrylamide toxicity using a battery of standardised bioassays.

Acrylamide is a monomer widely used as an intermediate in the production of organic chemicals, e.g. polyacrylamides (PAMs). Since PAMs are low cost chemicals with applications in various industries and waste- and drinking water treatment, a certain amount of non-polymerised acrylamide is expected to end up in waterways. PAMs are non-toxic but acrylamide induces neurotoxic effects in humans and genotoxic, reproductive, and carcinogenic effects in laboratory animals. In order to evaluate the effect of acrylamide on freshwater organisms, bioassays were conducted on four species: algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata, duckweed Lemna minor and water flea Daphnia magna according to ISO (International Organization for Standardisation) standardised methods. This approach ensures the evaluation of acrylamide toxicity on organisms with different levels of organisation and the comparability of results, and it examines the value of using a battery of low-cost standardised bioassays in the monitoring of pollution and contamination of aquatic ecosystems. These results showed that EC50 values were lower for Desmodesmus subspicatus and Pseudokirchneriella subcapitata than for Daphnia magna and Lemna minor, which suggests an increased sensitivity of algae to acrylamide. According to the toxic unit approach, the values estimated by the Lemna minor and Daphnia magna bioassays, classify acrylamide as slightly toxic (TU=0-1; Class 1). The results obtained from algal bioassays (Desmodesmus subspicatus and Pseudokirchneriella subcapitata) revealed the toxic effect of acrylamide (TU=1-10; Class 2) on these organisms.