1. Toxicity of selected copper oxide nanomaterials to the freshwater crustacean Daphnia magna
Z. Gajda-Meissner, M. Hartl, T. F. Fernandes
Heriot-Watt University , School of Life Sciences, Edinburgh, Scotland , EH14 4AS, UK
ABSTRACT
Engineered nanomaterials (ENMs) have been used in a growing number of commercial and industrial products and health-related applications due to their unusual physicochemical properties. The increasing use of ENMs and the uncertainties associated with their often poorly understood, biological effects, raises concern regarding their potential for causing unanticipated adverse effects. In this study the potential effects of copper oxide nanomaterials on Daphnia magna were investigated.
Initial studies were focused on D. magna and assessed the effects of copper oxide nanoparticles (nanomaterials with 3 dimensions between nm). Results from these tests have been compared with tests on copper chloride. D. magna (water flea) assays were performed according to OECD standard test 202 and 48-h acute toxicity data were obtained. All the tested compounds were suspended in synthetic freshwater (OECD M7 medium also used as a control). Test vessels with D. magna neonates were incubated for 48 h at 20 °C with a 16 hour light - 8 hour dark cycle in an incubation unit. Immobilization of the organisms was used as the toxicity endpoint.
Effective concentrations affecting x percent of the population ( EC50 values after 24 and 48 hours) for the parameter immobilization were calculated using SigmaPlot®.
The toxicity of nano CuO with different surface modification to Daphnia magna were very toxic: L(E)C50 (ug/l ) for copper oxide NMs EC (50, after 24 and 48 hours respectively) 240ug/l and ug/l; copper oxide with –COOH group ug/l and ug/l; copper oxide with NH3 group ug/l and ug/l; copper oxide with –PEG group 26.3 ug/l and ug/l and copper chloride as a positive control ug/l and 7.85 ug/l.
Future studies will be focused on chronic assays (eg reproduction) as well as genotoxicity and oxidative stress responses of Daphnia magna exposed to different nanomaterials. The activities of the antioxidant enzymes will be evaluated.
The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/ ) under grant agreement n°
OBJECTIVES
The effect of selected copper oxide NPs of the same size but different surface coatings was assessed on immobilization in Daphnia magna using acute toxicity standard OECD test 202.
METHODS
Acute toxicity test with Daphnia magna
Daphnia acute toxicity tests were performed according to the OECD test guideline 202 (n=5).
Data analyses
Effective concentrations (EC50 values after 24 and 48 hours) for the parameter immobilization were calculated using SigmaPlot®.
MATERIALS
The following nanomaterials were obtained from PlasmaChem (Germany):
• Copper oxide with -NH3 group 15 nm;
• Copper oxide with -COOH group 15 nm;
• Copper oxide with -PEG group 15nm;
• Copper oxide core 15nm.
Physico-chemical data
PROPERTIES
AVERAGE VALUE
Average primary particle size, nm
BET, m2/g
Purity
Stabilizer
Form
Colour
Phase
ca. ,15 nm
55+/- 5
99 %
None
Dry powder
Black
n.A.
CONCLUSIONS
The toxicity ranking of copper (both nano and salt forms) to Daphnia magna was as follows: CuO core < CuO + NH3 group < CuO +PEG group < CuO +COOH group < CuCl2
Copper oxide nanoparticles are highly toxic.
Surface modification is a significant driver in the toxicity of CuO NPs to Daphnia magna.
INTRODUCTION
The production of nanoparticles of CuO is increasing as they are used in a wide range of applications, for example in wood preservation and antimicrobial textiles (Cox, 1991 and Gabbay et al., 2006). The effects of different types of CuONPs were tested on the crustacean Daphnia magna.
The toxicity of NPs is closely related with many physicochemical characteristics such as: size, surface area, surface modification and radical formation. Currently, there are approximately ten major mechanistic pathways of toxicity that have been linked to ENMs.
The main mechanism of toxicity of NPs is thought to be via oxidative stress (OS) (Kohen and Nyska, 2002) that damages lipids, carbohydrates, proteins and DNA.
REFERENCES
C. Cox; Cromated copper arsenate. J. Pestic. Reform., 11 (1991), pp. 2–6
J. Gabbay, G. Borkow, J. Mishal, E. Magen, R. Zatcoff, Y. Shemer-Avni
Copper oxide impregnated textiles with potential biocidal activities.
J. Ind. Text., 35 (2006), pp. 323–335
R. Kohen, A. Nyska; Oxidation of biological systems: oxidative stress phenomena, antioxidants, redox reactions, and methods for their quantification. Toxicol. Pathol., 6 (2002), pp. 620–650
Error bars represent standard deviation values