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Table 1 Toxicity studies on inhalation of graphene derivatives involving various models Nanomaterial Evaluated Model Results Inference Article Reference Number Graphene oxide nanomaterials Single 6-hour, nose-only inhala- tion at low con- centration (0.46 ± 0.06 mg/m 3 ) and high concentra- tion (3.76 ± 0.24 mg/m 3 ) Sprague- Dawley rats No significant changes in the body or organ weights and food con- sumption Microalbumin and LDH levels in the BAL fluid were not significantly changed TCC, macrophages, polymorphonuclear leukocytes and lymphocytes were not significantly altered in the BAL fluid 5 Graphene oxide nanosheets Pulmonary surfactant film GO nanosheets induce pores in the PS film and thus show adverse effects on the ultrastructure and biophysical properties of the PS film Pores induced by GO nanosheets result in increased compressibility of the PS film 10 Graphene and graphite nano- platelets (0.5, 2.5, or 10 mg/m 3 for 6 hours per day on 5 con- secutive days) Male Wistar rats Microgranulomas were observed and inflammatory processes started at exposure concentration of 10 mg/m 3 for graphene No adverse effects were observed after inhalation exposure to 0.5, 2.5 mg/m 3 concentrations 6 Un-oxidized multilayered graphene platelets Mice Pristine GP showed minimal inflammation in mouse lungs after 6 weeks, even though large depos- its of GP were evident in the lungs GP in tissue sections showed minimal oxidation 7 Graphene Nose-only inhalation system; 6 hours per day for 5 days at low concentration (0.68 ± 0.14 mg/m 3 and high concen- tration (3.86 ± 0.94 mg/m 3 ) Male Sprague- Dawley rats No change in body weights or organ weights of the rats; no statisti- cally significant difference in the levels of LDH, protein and albumin No adverse effects were observed 8 Graphene aerosols Human airway replicas (nasal and oral-to- lung airways) Fractional deposition in airway sections were all less than 4%; the deposition efficiency in each air- way section was generally lower than 0.03 GA transit down to the lower lung airways which may result in undesired biological responses 9 Carbonaceous nanomaterials In vitro methodology (CDS) Graphene nanoplatelets induced a concentration-dependent PS inhi- bition under physiologically rele- vant conditions CDS can advance understanding of the ways submicron airborne nanomaterials affect the PS lining 4 GO = Graphene oxide; TCC = Total cell count; LDH = Lactate dehydrogenase; CDS = Constrained drop surfactometer; PS = Pulmonary surfactant; GPs = Graphene platelets; GA = Graphene aerosols; BAL = bronchoalveolar lavage Inhalation August 2017 21