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Influence of application techniques on the ecotoxicological effects of nanomaterials in soilKeywords: TiO2 nanoparticles, Ag nanoparticles, Terrestrial ecotoxicity, Soil application method Abstract: 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.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.The increasing use of nanotechnology means that nanomaterials will inevitably enter the environment. Ecotoxicological data are required for risk assessments, and a preliminary review concerning the application of OECD guidelines to manufactured nanomaterials [1] stated that the basic practices recommended by these guidelines are suitable for the testing of nanomaterials. However, guidelines for the delivery of substances to test systems, the quantitation of exposure, and the dose metrics, need to be adapted for the testing of nanomaterials. The guidance for sample preparation and dosimetry for the safety testing of manufactured nanomaterials does not provide detailed instructions for the application of nanomaterials in aqueous or non-aqueous media
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