Combination of in vitro bioassays for the determination of cytotoxic and genotoxic potential of wastewater, surface water and drinking water samples

In this study we evaluated genotoxicity and cytotoxicity of native samples of wastewaters (15 samples), surface waters (28 samples) and potable waters (8 samples) with the SOS/umuC assay with Salmonella typhimurium TA1535/pSK1002 and MTT assay with human hepatoma HepG2 cells. The genotoxicity of selected samples was confirmed with the comet assay with HepG2 cells. In the SOS/umuC assay 13 out of the 51 samples were genotoxic: two effluent samples from chemical industry; one sample of wastewater treatment plant effluent; two hospital wastewater samples; three river water samples and four lake water samples. Six samples were cytotoxic for HepG2 cells: both effluent samples of chemical industry, two wastewater treatment plant effluent samples, and two river water samples, however, only the chemical industry effluent samples were genotoxic and cytotoxic, indicating that different contaminants are responsible for genotoxic and toxic effects. Comparing genotoxicity of river and lake water samples with the chemical analytical data of the presence of the residues of pharmaceutical and personal care products (non-steroidal anti-inflammatory drugs, UV filters and disinfectants) in these samples, indicated that the presence of UV filters might be linked to the genotoxicity of these samples. The results showed that the application of the bacterial SOS/umuC assay and mammalian cell assays (MTT and comet assay) with HepG2 cells was suitably sensitive combination of assays to monitor genotoxicity and cytotoxicity of native samples of wastewaters and surface waters. With this study we also confirmed that the toxicity/genotoxicity bioassays should be an integral tool in the evaluation of toxicity of complex wastewaters before the release into environment, as well as for the monitoring of surface water quality, providing data useful in risk assessment.     

The effect of earthworms on the fractionation, mobility and bioavailability of Pb, Zn and Cd before and after soil leaching with EDTA

The effect of two ecologically contrasting earthworm species Eisenia fetida (epigeic) and Octolasion tyrtaeum (endogeic) on the fractionation (accessed using sequential extractions), mobility (toxicity characteristic leaching procedure, TCLP) and oral bioavailability (Ruby's physiologically based extraction test, PBET) of Pb, Zn and Cd was studied before and after soil remediation with soil leaching. Twenty-step leaching, with 2.5 mmol kg(-1) EDTA used in each step, removed 58.4%, 25.0% and 68.0% of initial soil Pb, Zn and Cd, respectively, shifted the fractionation of residual heavy metals toward less labile forms, and decreased their mobility by 83.7%, 80.3%, and 90.9%. Pb oral bioavailability was reduced by 3.1-times (in each stomach and intestinal phase). After soil leaching, both earthworm species enriched the carbonate soil fraction in their casts with residual Pb, and increased the Pb bioavailability in the simulated intestinal phase by a factor of 2.4 (E. fetida) and 2.8 (O. tyrtaeum). The concentration of Pb in TCLP leachate from E. fetida casts was 6.2-times higher than in the bulk of the remediated soil. These results indicate that the effect of biotic factors on the availability of heavy metals residual in soil after soil leaching requires consideration.     

Analyses of combined effects of cytostatic drugs on micronucleus formation in the <Emphasis Type="Italic">Tradescantia</Emphasis>

Recent experiments showed that 5-fluorouracil (5FU), cisplatin (CDDP), etoposide (ET), and imatinib mesylate (IM), which are currently among the most widely used anticancer drugs, cause damage of the genetic material in higher plants. The aim of the present study was to determine whether mixtures of these drugs cause synergistic or antagonistic effects which may have an impact on their environmental safety. Therefore, the effects of binary mixtures of these anticancer drugs on the induction of micronuclei (MN) which reflect structural and numerical chromosomal aberrations were assessed in Tradescantia tetrads. Synergistic/antagonistic effects were determined by comparison with single exposures that would be equally effective in a reference model of independent action. This comparison was performed at two distinct effect sizes. We found clear evidence for synergisms in combination experiments with IM and antagonism in a high-dose experiment with ET and 5FU. Our findings indicate that IM increases the genotoxic effects of other anticancer drugs. The maximal effects which we found were in the range between 19 and 38 % in the excess of effect sizes predicted under independent action. These effects may have an impact on the overall genotoxic activities of untreated hospital waste waters but not on the environment in general as the predicted environmental concentrations of the studied drugs are several orders of magnitude lower as the levels which are required to cause induction of MN in higher plants.     

Eisenia fetida avoidance behavior as a tool for assessing the efficiency of remediation of Pb, Zn and Cd polluted soil

Remediation by means of soil leaching with ethylenediaminetetraacetic acid (EDTA) is capable of extracting the most labile soil fractions, leaving the residual metals in biologically non-available forms. We evaluated the feasibility of the standardized earthworm (Eisenia fetida) avoidance test for assessing the efficiency of soil remediation of Pb, Zn and Cd polluted soil. Chemical extraction tests (six-step sequential extraction, toxicity characteristic leaching procedure, physiologically based extraction test, diethylenediaminepentaacetic acid extraction) indicated that the mobility, oral bioaccessibility and phytoavailability of Pb, Zn and Cd were consistently reduced. However, the avoidance test showed no significant avoidance of polluted soil in favor of that which had been remediated. Pb, Zn and Cd accumulation in E. fetida mirrored the decreasing pattern of metal potential bioavailability gained by leaching the soil with increasing EDTA concentrations. The calculated bioaccumulation factors indicated the possibility of underestimating the metal bioavailability in soil using chemical extraction tests.     

Fractionation and bioavailability of Cu in soil remediated by EDTA leaching and processed by earthworms (<Emphasis Type="Italic">Lumbricus terrestris</Emphasis> L.)

Background, aim, and scope  

Soil remediation with ethylenediamine tetraacetic acid (EDTA) leaching is capable of removing only part of the total metal concentration in the soil, mostly the labile, bioavailable metal species (metal bioavailability stripping). However, reintroduction of remediated soil in the environment exposes the soil to various environmental factors, which could potentially shift nonlabile residual metals back to labile bioavailable forms. We studied the effect of autochthonous earthworm species as model biotic environmental factor on the fractionation and bioavailability of Cu residual in soil after remediation.