Almost every person in all spheres of activity is in contact with nanoparticles (NPs) in the developed countries of the world. The use of NPs in medicine, in everyday life, in the food industry, and in many other areas is expanding. Therefore, in the 2010s, a new scientific direction - nanosafety - developed very actively. The consequences of contact with NPs for cells and tissues - inflammation, development of oxidative stress, disruption of the DNA structure, apoptosis, disruption of the functioning of tissues and organs - have already been studied quite well within the framework of the study of molecular and cellular toxicity. NPs with waste and emissions enter the air, water, soil and from them into living organisms. The impact of NPs on ecosystems is assessed in studies of the toxicity of NPs to the environment. NPs pose a significant danger to workers in production, where contact with NPs can be very long and chronic. In occupational pathology, data is already accumulating on NP-induced health problems and associated risk factors in workers in the nanotechnology industry. Due to the abundance of NPs in human life, expectant mothers and young children inevitably come into contact with them, therefore, the study of the influence of NPs on the intrauterine and early development of offspring is an important area of ​​research. The brain is a particularly vulnerable place for exposure to NPs due to their ability to cross the blood-brain barrier. Evidence of disturbances in the structure and functions of the brain in both adults and young animals is found in all areas of research into the toxicity of NPs. Methods for assessing various aspects of behavior, based on various brain functions, including cognitive ones, made it possible to obtain a clear idea of ​​the often negative consequences of contact with NPs for higher nervous activity. All these results are described in detail and systematically in the presented review. However, there is still considerable room for further research. In a number of studies, the toxic effect of NPs is not detected, and what affects its absence is not clear. Can these situations be used to protect against the toxic effects of NPs? These and other unresolved issues are also discussed in the review.