Browsing by Author "Vitorica, Joana"
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Item Acute toxicity of nanosized TiO2 to Daphnia magna under UVA irradiation(2012-11) Amiano, Irene; Olabarrieta, Josune; Vitorica, Joana; Zorita, Saioa; DF_Bioeficacia; ADAPTACIÓN AL CAMBIO CLIMÁTICOThe production and use of nanoparticles (NPs), especially those of titanium dioxide (TiO2) have increased steadily within the last decade. Common knowledge of photoactive nanosized TiO2 (nTiO2) effects on freshwater organisms is largely limited to acute toxicity tests without taking into consideration solar ultraviolet-A (UVA) irradiation. The authors' approach in the present study, based on a combination of a standardized ecotoxicology method (Organization for Economic Cooperation and Development [OECD] test 202) and the expected solar UVA contribution, will allow a more realistic understanding of the toxicity of TiO2 to Daphnia magna. The results show that the contribution of UVA to TiO2 toxicity cannot be ignored. The half-maximal effective concentration values (median effective concentration [EC50], immobilization as the endpoint) using Organization for Standardization (ISO) test water as well as river water decreased from 29.7 to 33.6mg/L under dark conditions to 1.2 to 3.4mg/L TiO2 after exposure to 0.56mW/cm2 UVA radiation. The authors also discuss possible mechanisms of NPs toxicity and the accuracy of results in terms of problems observed, such as solubilization and sedimentation of NPs, in ecotoxicological testing of nTiO2.Item UVA irradiation influence on the acute toxicity of nanosized TiO2 to Daphnia magna(TANGER Ltd., 2010) Amiano, Irene; Olabarrieta, Josune; Vitorica, Joana; Benguria, Pablo; Zorita, Saioa; DF_Bioeficacia; MATERIALES PARA CONDICIONES EXTREMAS; ADAPTACIÓN AL CAMBIO CLIMÁTICOThe incorporation of engineered nanoparticles in commercial products is progressively increasing and so is the potential for release of these novel materials into the environment. In fact, some recent studies demonstrate the release of nanomaterials, in particular nano-TiO2, from different ENP containing products such as sun-screens, paints, coatings etc. This implies that nanomaterials will reach the aquatic environment and that they could constitute a risk to aquatic organisms and humans. Common knowledge concerning photoactive nano-TiO2 effects on freshwater organisms is largely limited to acute toxicity tests without taking into consideration the solar UVA irradiation. Our approach based on the combination of a standardized ecotoxicology method (OECD test 202) with expected solar UVA contribution will allow more realistic understanding of the toxicity of nTiO2 to Daphnia magna. To reproduce the natural conditions of solar radiation, UVA-365 was monitored for 20 days during summer. The mean UVA intensity (0.56 mW/cm2) was chosen to reproduce the approximate radiation that the daphnids would be exposed to in a summer day. The results clearly demonstrate the higher toxicity of TiO2 nanoparticles to Daphnia magna when they are exposed to UV-light, therefore this factor should not be neglected when studying the ecotoxicity of photocatalytic nanomaterials. While TiO2 NPs can be classified as "harmful" to daphnids under darkness conditions (EC50 in the range 10-100 mg/L), when exposed to UVA they can be classified as "toxic" (EC50 in the range 1-10 mg/L). Water matrix was also taken into account, and thus, ecotoxicology tests were carried out in two different water matrices: river natural water and ISO test water.Item UVA irradiation influence on the acute toxicity of nanosized TIO2 to daphnia magna(TANGER Ltd., 2012) Amiano, Irene; Olabarrieta, Josune; Vitorica, Joana; Benguria, Pablo; Zorita, Saioa; DF_Bioeficacia; MATERIALES PARA CONDICIONES EXTREMAS; ADAPTACIÓN AL CAMBIO CLIMÁTICOThe incorporation of engineered nanoparticles in commercial products is progressively increasing and so is the potential for release of these novel materials into the environment. In fact, some recent studies demonstrate the release of nanomaterials, in particular nano-TiO2, from different ENP containing products such as sun-screens, paints, coatings etc. This implies that nanomaterials will reach the aquatic environment and that they could constitute a risk to aquatic organisms and humans. Common knowledge concerning photoactive nano-TiO2 effects on freshwater organisms is largely limited to acute toxicity tests without taking into consideration the solar UVA irradiation. Our approach based on the combination of a standardized ecotoxicology method (OECD test 202) with expected solar UVA contribution will allow more realistic understanding of the toxicity of nTiO2 to Daphnia magna. To reproduce the natural conditions of solar radiation, UVA-365 was monitored for 20 days during summer. The mean UVA intensity (0.56 mW/cm2) was chosen to reproduce the approximate radiation that the daphnids would be exposed to in a summer day. The results clearly demonstrate the higher toxicity of TiO2 nanoparticles to Daphnia magna when they are exposed to UV-light, therefore this factor should not be neglected when studying the ecotoxicity of photocatalytic nanomaterials. While TiO2 NPs can be classified as "harmful" to daphnids under darkness conditions (EC50 in the range 10-100 mg/L), when exposed to UVA they can be classified as "toxic" (EC50 in the range 1-10 mg/L). Water matrix was also taken into account, and thus, ecotoxicology tests were carried out in two different water matrices: river natural water and ISO test water.