Current status and considerations of ecotoxicity testing methods for cellulose nanofibers

Abstract

To develop ecotoxicity test methods for the ecological impact assessment of cellulose nanofibers (CNFs) in aquatic environments, we summarized the methods and results of ecotoxicity tests used in published articles. We also discussed the points to be considered while conducting ecotoxicity tests for CNFs using aquatic organisms based on the Organisation for Economic Co-operation and Development (OECD) guidance document No. 317 for ecotoxicity testing of nanomaterials. In some published articles, no ecological effects of CNFs on aquatic organisms were observed, even when they were exposed to high concentrations of CNFs. In these studies, test organisms may not have been exposed to nominal concentrations of CNFs because of CNF agglomeration and settling caused due to the low dispersion stability of CNFs resulting from the water quality of the test medium. According to the OECD guidance document, attention must be paid toward dispersibility and dispersion stability, effects of feeding, and factors related to adverse effects, analysis, and measurement of CNFs. No literature was found that reported on all these aspects of testing. Future examination of ecological effects of CNFs needs to consider measuring actual exposure concentrations by evaluating dispersibility and dispersion stability of CNFs.