Long-term Effects of CuO Nanoparticles on Hyalella azteca - Implications for Environmental Risk Assessment

Julie Zwicky Burkal, Nina Falk Gregersen & Julie Thalia Reventlow

Studenteropgave: Speciale

Abstrakt

Due to the specific properties nanoparticles (NPs) are increasingly used in a wide range of products. The rapid development within the field has resulted in a demand for recon- siderations of the current risk assessment methods, as NPs differ greatly from their bulk counterparts and many factors including the toxic mechanisms are not yet fully understood. In this study, the effects of copper oxide nanoparticles (CuO NPs) on the freshwater amphi- pod, Hyalella azteca, were investigated in order to evaluate the ecotoxicological differences between the nano and the ionic form of Cu. The CuO NPs were characterised by DLS, zeta potential, TEM and dissolution. Juvenile organisms were exposed to 25, 50 and 100 μg Cu/L added as either CuO NPs or CuCl2 in water for 50 days. Effects on growth, mortality, pre- copulation as well as bioaccumulation were measured. Potential delayed effects and ability to recover from Cu exposure were further assessed by transferring half the organisms to clean environment after 25 days of exposure. Growth inhibition as well as lack of precopulation was observed for organisms exposed to CuCl2 at all concentrations. The organisms transferred to clean environment after CuCl2 exposure showed similar effects, indicating no recovery from Cu exposure. Length and precopulation pattern of organisms exposed to either of the CuO NPs treatments were similar to that of control organisms. The risk assessment of NPs under REACH is subject to a number of challenges, due to the high diversity among NPs of the same chemical composition and knowledge gaps within fate and effects in the environment. Further, methods for particle characterisation and standard- ised test guidelines needs to be re-evaluated, as these are important for the risk assessment process. The current risk assessment methods have been evaluated for applicability to NPs and a range of additional physical-chemical properties and ecotoxicological endpoints have been recommended. However, current registration of NPs does not consistently take these into account, resulting in inconsistent registrations of NPs. The effects observed in the experiment are likely to result from the release of Cu ions, as the ion release in the dissolution study was five times higher for CuCl2 than for the CuO NPs. This was supported by calculations based on ionic effect concentrations of CuCl2 and CuO NPs. However, other studies have shown effects of the particles themselves or a combination of particles and ions further supporting the demand for nano-specific test guidelines.

UddannelserMiljørisiko, (Bachelor/kandidatuddannelse) Kandidat
SprogEngelsk
Udgivelsesdato15 aug. 2015
VejledereKristian Syberg

Emneord

  • hyalella azteca
  • nanoparticles
  • ecotoxicology
  • copper
  • environmental risk assessment
  • long-term