Exposure to Copper Nanoparticles Causes Gill Injury and Acute Lethality in Zebrafish (Danio rerio)

Abstract

Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50–60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 µg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.

Comparative environmental fate and toxicity of copper nanomaterials

“…The lower toxicity of nCuO in freshwater may reflect its slower dissolution at low ionic strengths and Cu + 2 complexation in the presence of organic matter Garner and Keller, 2014;Griffitt et al, 2007;Blinova et al, 2010;Mortimer et al, 2010;Garner et al, 2015;Wang et al, 2011). Other studies indicate that the toxic effect observed from nCuO strongly correlates with the fraction of NP dissolved in aquatic media (Garner and Keller, 2014;Blinova et al, 2010;Aruoja et al, 2009).…”

“…Given their high density (8.96 g/cm 3 for nCu, 6.31 g/cm 3 for nCuO), Cu NPs settle out rapidly once they reach micron scale. nCu, with an isoelectric point (IEP) of pH 2.1, rapidly forms highly polydisperse micron-scale aggregates in simple salt solutions and natural waters (Conway et al, 2015a), both in the absence and presence of organisms (Griffitt et al, 2007). Rapid aggregation of nCu leads to fast sedimentation; for instance, only 20% of initial nCu mass was detected after 6 h in 10 mM NaCl at pH 7 .…”

“…Rapid aggregation of nCu leads to fast sedimentation; for instance, only 20% of initial nCu mass was detected after 6 h in 10 mM NaCl at pH 7 . However, in the presence of zebrafish and moderately hard freshwater,~40% of the initial mass of nCu remained suspended after 48 h, indicating a fraction of the nanoparticles may have been stabilized by NOM released by the fish (Griffitt et al, 2007).…”

“…For Cu + 2 , 24-h LC 50 ranges from 0.086 μg/L to 282 mg/L for a wide range of organisms, with a median of 5.8 mg/L. (ECOTOX Database, 2014) Although there are only a few studies on the toxicity of nCu, 48-h LC 50 ranges from 47 μg/L to 419 μg/L for Ceriodaphnia dubia (Gao et al, 2009;Griffitt et al, 2008) and from 700 μg/L to 1500 μg/L for Danio rerio juveniles and adults (Griffitt et al, 2007;Griffitt et al, 2008). For nCuO, 24-h LC 50 ranges from 470 μg/L to 217 mg/L (Manusadžianas et al, 2012;Heinlaan et al, 2008;Blinova et al, 2010;Gallego et al, 2007), while 24-h EC 50 ranges from 30 μg/L to 126 mg/L across several organisms (Blinova et al, 2010;Mortimer et al, 2011;Kasemets et al, 2009;Mortimer et al, 2010;Jo et al, 2012).…”

Toxicity assessment on haemotology, biochemical and histopathological alterations of silver nanoparticles-exposed freshwater fish Labeo rohita

“…The toxicological evidence of AgNPs is still lacking and the safety measurements for these nanoparticles have to be framed. The engineered nanomaterials comprise of numerous different physical forms and some of these materials including carbon nanotubes, carbon spheres called fullerenes (Zhu et al 2006) and nanoparticles made from metals (Griffitt et al 2007), metal oxides (Federici et al 2007) or composites made of several metals (King-Heiden et al 2009) have adverse effects on fish (Smith et al 2007). To study the aquatic toxicity, fish species has been widely used as an indicator of pollutant and they strongly respond to stress conditions.…”