Engineered nanomaterials in soil: Problems in assessing their effect on living organisms

Studies on the occurrence and potential effects of nanomaterials (NMs) in the environment are analyzed. Mechanisms of action of some of the well-known nanotechnological products on test cultures are discussed. Attention is focused on the problems of determination of the ecotoxicity of NMs in soils in relation to their instability and variability in the environmental conditions. Our data indicate that the effect of the interactions between the nanoparticles should be taken into consideration in econanotoxicological studies. The formation of aggregates at high concentrations of nanoparticles and an increase in the content of free nanoparticles upon dilution largely explain the inverted dose-response ratio, or the U-shaped curve describing this relationship in the analysis of dispersed systems. Problems in the development of an assessment system for the effect of NMs on environments, including soils, are also discussed. Presently, there are no standards for assessing NMs, and approved Russian and international procedures for checking the sensitivity of standardized test organisms are used. However, the imperfection of the approaches to the analysis of NMs toxicity gives no ground for hampering the development of nanotechnologies for nature conservation purposes.