Ecotoxicological assessment of nanoparticle-containing acrylic copolymer dispersions in fairy shrimp and zebrafish embryos†
Nanoparticle-containing polymer dispersions are widely used, but little is known of their environmental effects. We studied the bioavailability, uptake, tissue localisation and effects of nanoparticle-containing acrylic copolymer (ACP) dispersions (mean nanoparticle sizes: 80 nm and 110 nm) in aquatic invertebrates (Thamnocephalus platyurus; fairy shrimp) and Danio rerio zebrafish embryos after aquatic exposures. Dietary exposure tests were enabled using Casper zebrafish that lack skin pigmentation allowing for bio-imaging of uptake and internal distribution. Aqueous exposures of 1000 and 2500 mg L−1 80 nm-ACP or 110 nm-ACP showed no acute toxicity in fairy shrimp or zebrafish, constituting a non-toxic classification according to the United Nations Globally Harmonised System of Classification and Labelling of Chemicals threshold (100 mg L−1). Similarly, dietary exposures resulted in no ecotoxicological effects. In Casper zebrafish fed with 80 nm-ACP-spiked food, hyperspectral signals derived using coherent Raman scattering (CRS) indicated that test material was present in the intestine, and possibly in the liver, but not in other organs. CRS imaging indicated that the chemical composition of the yolk sac of an 80 nm-ACP exposed zebrafish (aquatic exposure) was altered, attributed to a change in lipid metabolism, although we could not confirm with certainty that the test material was physically present in the yolk sac. These results illustrate how CRS microscopy can be used to investigate the bioaccumulation of organic nanomaterials, provided that they induce hyperspectral profiles distinct from the biological samples. In conclusion, both 80 nm- and 110 nm-ACP dispersions are internalised through dietary exposure, but are not associated with significant toxic effects.