As the production of metal-based nanomaterials increases, it is inevitable
that nano-scale products and byproducts will enter the aquatic environment.
In terms of global production, the most abundant nano-oxides are TiO2, CeO2
and Fe3O4 nanoparticles. Chironomus riparius is commonly used for
ecotoxicological assessment and defining its histopathological biomarkers
that showcase the toxic effect of tested nanoparticles should lead to a
better understanding of the consequences of nanomaterial accumulation in
aquatic ecosystems. In this study, a histological description of the
digestive and excretory systems as well as the fat body structure of C.
riparius larvae is provided. In addition, potential histological biomarkers
of nano-oxide toxicity were determined based on the obtained
histopathological alterations in organs. Vacuolization was observed in
epithelial cells of midgut region I that were treated with nano-Fe3O4 as
well as in Malpighian tubules treated with nano-Fe3O4 and nano-CeO2. Larvae
exposed to nano-TiO2 showed alterations in the fat body and midgut region II
tissue architecture. Additionally, shortening of the intestinal brush border
was determined in groups exposed to nano-Fe3O4. These results reveal the
high sensitivity of these organs, which can be used as biomarkers in
histopathological assessment and therefore lead to further improvement of
existing methodology in ecotoxicological studies.
Histopathology of Chironomus riparius (Diptera, Chironomidae) exposed to metal oxide nanoparticles