1,721,028 research outputs found
Beurteilung der Gesamtumweltexposition von Silberionen aus Biozid-Produkten
Full text linkBEURTEILUNG DER GESAMTUMWELTEXPOSITION VON SILBERIONEN AUS BIOZID-PRODUKTEN
Beurteilung der Gesamtumweltexposition von Silberionen aus Biozid-Produkten / Hund-Rinke, Kerstin (Rights reserved) (-
Single versus repeated applications of CuO and Ag nanomaterials and their effect on soil microflora
No full textAbstractNanomaterials enter the terrestrial environment via the repeated application of sludge to soils over many years. The goal of this investigation was to compare the effects of CuO and Ag nanomaterials on soil microorganisms after a single application and after repeated applications ultimately resulting in the same test concentrations. The effect on soil microorganisms was determined using the ammonium oxidation (ISO 15685), enzymatic activity patterns (ISO 22939) and MicroResp™ tests on days 28, 56 and 84. The comparability of single and repeated applications of ion-releasing nanomaterials depended on the test endpoint and duration. No significant differences between single and repeated applications were observed when testing nitrifying microorganisms and exoenzymes, but differences were observed in the substrate-induced respiration test. The three test systems used together provide more comprehensive information about the impact of different nanomaterials on the soil microflora and its diversity
Regenwurmtests in der Ökotoxikologie
Full text linkZur Beurteilung der Lebensraumfunktion von Böden haben sich unter anderem Regenwurmtests etabliert. Dabei stehen drei Testsysteme mit den Endpunkten Mortalität, Reproduktion und Fluchtverhalten zur Verfügung. Alle Verfahren sind mittlerweile als genormte Methodenvorschrift verfügbar. Darüber hinaus werden zahlreiche Biomarker berichtet, die jedoch für die Bodenbeurteilung bislang noch nicht ausreichend validiert sind
Influence of soil properties on the effect of silver nanomaterials on microbial activity in five soils
No full textAbstractWe investigated the effects of silver nanomaterials (AgNMs) on five well-characterized soils with distinct physicochemical properties using two standardized test systems. The carbon transformation test (OECD 217) showed minimal sensitivity whereas the ammonia oxidizing bacteria test (ISO 15685) showed extreme sensitivity over 28 days of exposure. AgNM toxicity was compared with the physicochemical properties of the soils, revealing that toxicity declined with increasing clay content and increasing pH. AgNM toxicity did not appear to be affected by the organic carbon content of the soil. Our results showed that AgNM toxicity cannot be attributed to any single soil property but depends on the same parameters that determine the toxicity of conventional chemicals. Recommendations in the test guidelines for soil ecotoxicity studies are therefore applicable to AgNMs as well as conventional chemicals
The potential benefits and limitations of different test procedures to determine the effects of Ag nanomaterials and AgNO3 on microbial nitrogen transformation in soil
No full textArt.28, 12 S.Background: The procedure described in The Organisation for Economic Co-operation and Development (OECD) test guideline (TG) 216 is used to assess the effects of chemicals on microbial nitrogen transformation in soil, and the results are considered in regulatory risk assessments. We investigated the suitability of this method to characterize the effects of two silver nanomaterials and a soluble silver salt. We applied three different test procedures: (i) nitrogen transformation using the complex organic nitrogen source lucerne meal (OECD TG 216), (ii) nitrogen transformation using the inorganic nitrogen source (NH4)2SO4 (following OECD TG 216), and (iii) ammonium oxidation (ISO 15685). The results were compared with substrate-induced respiration (OECD TG 217). Results: The standard nitrogen transformation test using lucerne meal suggested that the test materials had no effect, whereas significant effects were identified with the other two test procedures. The absence of effects with lucerne meal probably reflected the sorption of silver ions to the additional organic nitrogen source, thus reducing its bioavailability, or blocking the silver nanomaterial oxidation sites by sorption of organic matter. Conclusions: This common test used in the context of chemical registration is therefore unsuitable for the detection of potential effects caused by silver nanomaterials and soluble silver salts because it can yield false negative results. We instead recommend the use of an inorganic nitrogen source. The observed effects were not specific to nanomaterials. The time course of the effect in the nitrogen transformation test based on (NH4)2SO4 and the potential ammonium oxidation test varied according to the test substance, indicating different kinetic behaviors of ion release.26Nr.
Testing particles using the algal growth inhibition test (OECD 201): the suitability of in vivo chlorophyll fluorescence measurements
No full textBackground:
The freshwater algae and cyanobacteria growth inhibition test (OECD test guideline 201) is frequently used to assess the ecotoxicity of chemicals or particles. A central issue is the measurement of algal growth by quantifying algal biomass over time. Chlorophyll fluorescence measurements are recommended for the testing of particles. The analysis of in vivo fluorescence is the simplest and fastest approach, but is only suitable if there is no interference with the materials. Therefore, in vitro fluorescence analysis is often preferred. We carried out a comprehensive comparison of chlorophyll fluorescence measurements in vitro and in vivo to evaluate the suitability of rapid in vivo testing for the determination of Raphidocelis subcapitata biomass in the presence of diverse particles.
Results:
For the in vitro measurement, we applied a method that separates particles from chlorophyll using locust bean gum. We tested inorganic and organic particles (including alloys and polymers), ion-releasing and non-releasing materials, and particle sizes in the nanometer to micrometer range with a variety of shapes (spherical, flaky and fibrous). Some of the materials were nontoxic, whereas others showed varying degrees of toxicity (ErC50 = 0.2-100 mg/L in both methods). There were only minor differences between the methods in ErC50 values and the percent inhibition at various test concentrations, but the confidence intervals for the ErC50 values in vivo were narrower and were covered by the range observed in vitro. The in vivo approach showed no limitations, whereas the validity criteria listed in OECD test guideline 201 were not always fulfilled by the in vitro measurements.
Conclusion:
The in vivo approach was a suitable and time-saving method for a wide range of particles, although we cannot completely exclude the possibility that some particles may interfere with fluorescence measurement. To avoid false assessments, pre-tests with simple measurements are therefore recommended.3
Influence of application techniques on the ecotoxicological effects of nanomaterials in soil
No full textArt. 30, 12 S.Background: In terrestrial ecotoxicological tests, the availability and ecotoxicity of solid nanomaterials may depend on the application technique. We compared five spiking procedures using solid uncoated TiO2 and Ag nanoparticles in standardized OECD tests with earthworms, plants and soil microflora: dry spiking of soil by applying soil or silica sand as a carrier; dry spiking of food without a carrier; and wet spiking of soil and food with an aqueous nanoparticle dispersion. Results: The effects of the nanomaterials were influenced by the application technique. The differences were independent of the test organism (which represented different habitats and exposure pathways) and the specificity of the effect (stimulation or inhibition). Wet spiking resulted in stronger effects than dry spiking, but the bioavailability of the particles appeared to be limited when highly-concentrated nanoparticle suspensions were used for wet spiking. The availability of the nanoparticles was slightly lower when silica sand rather than soil was used as the carrier for dry spiking, but the matrix itself (soil or food) had no effect. Conclusion: There are indications that the concentrations of the stock suspensions influence the test results, so dry spiking is preferred for solid TiO2 and Ag nanoparticles. We achieved satisfactory spiking homogeneity with Ag nanoparticles using soil as a solid carrier. Further experiments with other carriers and soil types are required to confirm that the observed differences are universal in character. There was no difference in effect when TiO2 nanoparticles were applied via food or soil. The spiking of soil instead of food is preferred for TiO2 nanoparticles, as is the case for conventional chemicals.2
Effect of TiO2 nanoparticles in the earthworm reproduction test
No full textBackground: The increasing use of nanotechnology means that nanomaterials will enter the environment. Ecotoxicological data are therefore required so that adequate risk assessments can be carried out. In this study, we used a standardized earthworm reproduction test with Eisenia andrei to evaluate three types of TiO2 nanoparticles (NM-101, NM-102, NM-103). The test was performed in natural sandy soil (RefeSol 01A) following Organisation for Economic Co-operation and Development Test Guideline No. 222. The nanoparticles differed in several aspects, such as crystalline structure, size, and the presence or absence of a coating. Results: Uncoated nanoparticles stimulated earthworm reproduction in a concentration-dependent manner during winter testing, increasing the number of offspring by up to 50% compared to the control. However, there was no stimulation when the same test was performed in the summer. This reflected an underlying circannual rhythm observed in the control soil, characterized by the production of a significantly larger number of juveniles in summer compared with that in winter. The effect of the uncoated TiO2 nanoparticles was to reduce or eliminate the circannual differences by increasing the reproductive rate in winter. Coated TiO2 nanoparticles did not influence earthworm reproduction. Conclusion: TiO2 appears to affect earthworm reproductive activity by abolishing the circannual rhythm that depresses reproduction in the winter. Further experiments will be necessary to determine (1) the mode of action of the nanoparticles, (2) the important parameters causing the effect (e.g., relevant soil parameters), and (3) the environmental relevance of continuous earthworm reproduction we observed under laboratory conditions.24
Single versus repeated applications of CuO and Ag nanomaterials and their effect on soil microflora
No full text322330Nanomaterials enter the terrestrial environment via the repeated application of sludge to soils over many years. The goal of this investigation was to compare the effects of CuO and Ag nanomaterials on soil microorganisms after a single application and after repeated applications ultimately resulting in the same test concentrations. The effect on soil microorganisms was determined using the ammonium oxidation (ISO 15685), enzymatic activity patterns (ISO 22939) and MicroResp tests on days 28, 56 and 84. The comparability of single and repeated applications of ion-releasing nanomaterials depended on the test endpoint and duration. No significant differences between single and repeated applications were observed when testing nitrifying microorganisms and exoenzymes, but differences were observed in the substrate-induced respiration test. The three test systems used together provide more comprehensive information about the impact of different nanomaterials on the soil microflora and its diversity.21
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