A Framework to Evaluate the Impact of Armourstones on the Chemical Quality of Surface Water.

Today, basic requirements for construction works include the protection of human health and of the environment. In the tension area between economic demands, circular flow economy and environmental safety, a link between the results from standardized leaching tests and the respective environmental quality standards must be created. To derive maximum release limits of metals and metalloids for armourstones in hydraulic engineering, this link is accomplished via a simple model approach. By treating natural materials and industrial by-products the same way, the article delivers an overview on the recent regulative situation in Europe as well as describes and discusses an innovative approach to derive maximum release limits for monolithic construction products in hydraulic engineering on a conceptual level. On a practical level, a list of test parameters is derived by connecting an extensive dataset (seven armourstone materials with five repetitions and 31 elements tested with the worldwide applied dynamic surface leaching test) with surface water quality standards and predicted no effect concentrations. Finally, the leaching tests results are compared with the envisaged maximum release limits, offering a direct comparison between natural materials and industrial by-products.

Completely automated short-term genotoxicity testing for the assessment of chemicals and characterisation of contaminated soils and waste waters.

GOAL, SCOPE AND BACKGROUND: The umu-test was developed for the detection of effects of chemical mutagens and carcinogens in environmental samples. It is performed according to ISO 13829 with Salmonella choleraesius subsp. chol. (strain TA1535/pSK1002). By automating the entire test, large numbers of toxicants and environmental samples as well as more treatments and parallels can be tested and, additionally, only low sample volumes are needed. In this work, an automated umu-test has been set up by installing a robotic XYZ-platform and a microplate reader inside a cabin. The use of established technical equipment for the automation in combination with a performance according to ISO standards was the essential aim of the approach. After initial preparation, the test is conducted software-controlled, follows the standard and fulfils the validity criteria of the standard procedure. For the optimization of the automated test umu-tests with one concentration of methyl methanesulfonate (MMS) of 166.7 mg/L were carried out. After optimization of incubation and pipetting conditions in the automated test, dose-response curves of various chemicals and environmental samples were assessed. The results of the automated umu-test have been compared with those of the standard manual test. The aim of the study was to show the applicability of an automated test system for the assessment of the genotoxic effects of various chemicals and environmental samples. METHODS: During optimization, tests with 166.7 mg/L of MMS in every well of the microplate are carried out. Chemicals with different physical, chemical and toxicological properties are applied in both test systems. Water samples from different waste water treatment plants, and water extracts of contaminated and uncontaminated soils are assessed in the umu-test. The test is performed in parallel manually according to the standard and automatically using the robotic platform. Dose-response relationships and DLI-values are recorded and compared. RESULTS: The umu-test is applied on a RoboSeq 4204 SE pipetting station (MWG AG, Ebersberg, Germany). The robot is equipped with four holders for disposable tips to avoid undesired mixing of liquids while testing. With this system, it is possible to pipette all liquids. Photometric measurements are performed using a microplate reader. The pipetting station and the photometer are placed in an incubation cabin. According to the standards, exposure and growth of the bacteria are performed at 37 degrees C and the enzyme activity is assessed at 28 degrees C. Since both temperatures can't be adjusted simultaneously in the cabin, the test is performed in deviation from the standard at 33 degrees C. The results show that both the testing of non-volatile substances with strong or moderate genotoxic effects and the testing of water and soil samples in the automatic system work very well. Nevertheless, it is still difficult to characterize volatile chemicals automatically. This is illustrated, e.g. by testing 2- +/- -hydroxyquinoline. In this case, the chemical would not be assessed genotoxically after automatic performance of the umu-test. Sealing of the microplates, for example, avoids the loss of volatile substances, but this step of the procedure can not be performed automatically. Discussion. Only very few studies deal with the automation of bioassays. Eisentraeger et al. (2004) showed the suitability of a miniaturized and automated algae test for the testing of large numbers of environmental samples. Genotoxicity with an automated liquid handling are introduced by White et al. (1996) and Janz et al. (1989). A complete automation including liquid handling, incubation and photometric measurement is a new approach and leads to satisfying results. CONCLUSIONS: Optimization and suitability of the automated test are demonstrated in this study. Induction rates and growth factors do not differ significantly if the incubation temperature and the pipetting mode are optimized. Due to flexible scripting, the newly developed automated test system can also be used to perform other genotoxicity tests. Most results clearly show that genotoxicity tests can be automated completely allowing rapid testing that can be performed over night, for instance. Nevertheless, the test performance has to be optimized step by step depending on the technical characteristics of the automat. In order to overcome these technical problems, detailed knowledge of the hardware and the software of the automat and of the respective genotoxicity test system are needed. During this process of automation, it is very useful to test one genotoxic substance with an identical concentration in every well. RECOMMENDATIONS AND PERSPECTIVES: The automated test system based on the RoboSeq 4204 SE pipetting station (MWG AG, Ebersberg, Germany) still has to be optimized with respect to the testing of volatile compounds. There is a need for removable, gas-tight microplate covers. For non-volatile chemicals and environmental samples, it can be used routinely. Nevertheless, the experiences made during this study can only partly be transferred to other robotic platforms and other bioassays, and automation of bioassays still can be a time-consuming matter.

Heterocyclic compounds: toxic effects using algae, daphnids, and the Salmonella/microsome test taking methodical quantitative aspects into account.

Heterocyclic aromatic hydrocarbons containing nitrogen, sulfur, or oxygen (NSO-HET), have been detected in air, soil, sewage sludge, marine environments, and freshwater sediments. Since toxicity data on this class of substances are scarce, the present study focuses on possible implications NSO-HET have for ecotoxicity (algae and daphnids) and mutagenicity (Salmonella/microsome test). A combination of bioassays and chemical-analytical quantification of the test compounds during toxicity assays should aid in determination of the hazard potential. Samples of the test concentrations of 14 NSO-HET were taken at the beginning and end of the bioassays; these samples were then quantified by high-performance liquid chromatography. The toxicity potential of the substances was evaluated and compared with the toxicity calculated with the nominal concentrations. Significantly different results were obtained primarily for volatile or highly hydrophobic NSO-HET. The concentration of heterocyclic hydrocarbons can change significantly during the algae and Daphnia test. The EC50 values (effective concentration value: the concentration of a chemical that is required to produce a 50% effect) calculated with the nominal concentrations underestimate the toxicity by a factor of up to 50. Prioritizing the tested compounds according to toxicity, the mutagenic and toxic compounds quinoline, 6-methylquinoline, and xanthene have to be listed first. The greatest ecotoxic potential on algae and daphnids was determined for dibenzothiophene followed by acridine. In the Daphnia magna immobilization test, benzofuran, dibenzofuran, 2-methylbenzofuran, and 2,3-dimethylbenzofuran and also carbazole are ecotoxicologically relevant with EC50 values below 10 mg/L. These substances are followed by indole with a high ecotoxic effect to daphnids and less effect to algae. Only minor toxic effects were observed for 2-methylpyridine and 2,4,6-trimethylpyridine.