The Relative Citation Ratio of the investigated group of publications in 2011, which was 2.57, decreased until 2015 (to 1.73), but after that, it constantly increased, reaching 2.23 by 2018. The Relative Citation Ratio (RCR) is a new metric recently endorsed by the National Institutes of Health. It is based on weighting the number of citations a paper receives to a comparison group within the same field . The research area is defined by the corpus of publications co-cited with the article of interest (the "co-citation network")it is therefore dynamically defined. In other words, the RCR indicates how a publication has been cited relative to other publications in its co-citation network, and this is assumed to be reflective of the article's area of research. The key aspect of the derivation of the RCR is that it is benchmarked to NIH R01-funded articles. If the article's RCR value is 1.0the article is in the median for NIH R01-funded articles for that year. This definition leads to a clear interpretation of RCR values: RCR value of 1.0 is the boundary between articles with a citation rate lower than the median NIH R01-funded publication and those with a higher citation rate . Thus, the annual increase in the number of publications and citations indicates the great importance of nanotoxicological research in the general field of research on nanobiotechnology.