Co-exposure of ZnO nanoparticles and UV radiation to Daphnia magna and Danio rerio: Combined effects rather than protection.
The application of nanoparticles (NPs) in consumer products has been increasing over the past few years. Their release into the environment is likely to happen at any stage of production or during the use of products containing NPs. Zinc oxide NPs (ZnO-NP) are among the most-used NPs on the market due to its intrinsic properties, such as ultraviolet (UV) absorption. The aim of the present study was to assess the combined effects of ZnO-NP and UV radiation on 2 freshwater species: Daphnia magna and Danio rerio. The initial hypothesis was that the presence of ZnO-NP in the aquatic media would decrease the damaging effects of UV radiation for both species. The endpoints assessed for D. magna were immobilization, feeding inhibition, and reproduction output. For D. rerio, egg development was studied during 96 h and mortality, hatching delay, and abnormal development were the endpoints recorded. Combined exposures were designed based on the single toxicity of both stressors and analyzed based on the independent action concept and exploring possible deviations for synergism/antagonism, dose level, and dose ratio. Combined exposures with D. magna induced synergism on reproduction, decreasing the number of neonates produced more than expected based on both stressors' individual toxicity. Single exposures of D. rerio embryos to both stressors induced negative effects. The combined exposures caused a dose-ratio deviation pattern on mortality and hatching, with a synergism observed when ZnO-NP was the dominant stressor, changing to antagonism when UV radiation dominated the combined exposure. Regarding the results attained, studying ZnO toxicity under laboratory conditions may underestimate the risks when considering the potential interaction on effects when combined with UV radiation.
Department of Biology and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.
Sofia L
SL
Azevedo
Department of Biology and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.
Fabianne
F
Ribeiro
Department of Materials, Begbroke Science Park, Oxford University, United Kingdom.
Kerstin
K
Jurkschat
Department of Biology and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.
Amadeu M V M
AM
Soares
Department of Biology and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.
Susana
S
Loureiro
D000818:Animals; D000831:Animals, Newborn; D003621:Daphnia / Q000187:drug effects* / Q000528:radiation effects*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000528:radiation effects; D047108:Embryonic Development / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D053768:Metal Nanoparticles / Q000633:toxicity*; D009043:Motor Activity / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects; D014466:Ultraviolet Rays; D015027:Zebrafish; D015034:Zinc Oxide / Q000633:toxicity*
D015034:Zinc Oxide
Danio rerio; Daphnia magna; UV radiation; ZnO nanoparticle