Figure 2

Overall summary of the reviewed nanorelease studies. Several key details about all fifty-four nanorelease studies we identified and discuss in this review are presented in the table. While the experimental studies are highlighted, all provide information about which nanomaterials have been added to different base matrices and examined under the various release scenarios. The debris released is most often a mixture of multiple types, particle of matrix alone, particles of matrix with the nanomaterial embedded and the nanomaterial fully dissociated from the matrix. In addition, a few studies did not identify any release, or clearly identified the release of ionic forms of the added nanomaterial, but not the nanomaterial itself. Across study summaries are present in charts: (A) the added nanomaterial, (B) the matrix, (C) the release scenario examined, (D) the released debris identified and (E) the number of experiments versus observational studies. (#) Authors used GFAAS, which incinerates the matrix in the process of identifying chemical composition. Thus we are unable to determine if the nanomaterial was bound to, or dissociated from the matrix; (*) Authors report release only after a combination of weathering and machining; (-) authors report insignificant but detectable levels of dissociated nanomaterial; (?) data supporting this result are indirect or not presented, but described by the authors; (exp) rigorous experiments with replicate testing and negative controls (samples of matrix without added nanomaterial) examined; (obs) observational studies with no control samples and/or not replicate testing; (C) refers to any one of multiple forms of Carbonaceous nanomaterials, including: single and multi-walled carbon nanotubes, graphene oxide, carbon black and uncharacterized carbon nanotubes; (CSH) are calcium silicate hydrates; (%) a complex copper II with chlorinated phthalocyanine; (@) alumina based Cobalt Blue.