A number of studies have been published concerning the potential ecotoxicological risks of titanium dioxide nanoparticles (nano-TiO2), but the results still remain inconclusive. The characteristics of the diverse types of nano-TiO2 must be considered in order to establish experimental models to study their toxicity. TiO2 has important photocatalytic properties, and its photoactivation occurs in the ultraviolet (UV) range. The aim of this study was to investigate the toxicity of nano-TiO2 to indicators organisms of freshwater and saline aquatic systems, under different illumination conditions (visible light, with or without UV light). Daphnia similis and Artemia salina were co-exposed to a sublethal dose of UV light and different concentrations of nano-TiO2 in the form of anatase (TA) or an anatase/rutile mixture (TM). Both products were considered practically non-toxic under visible light to D. similis and A. salina (EC5048h > 100 mg/L). Exposure to nano-TiO2 under visible and UV light enhanced the toxicity of both products. In the case of D. similis, TM was more toxic than TA, showing values of EC5048h = 60.16 and 750.55 mg/L, respectively. A. salina was more sensitive than D. similis, with EC5048h = 4 mg/L for both products. Measurements were made of the growth rates of exposed organisms, together with biomarkers of oxidative stress and metabolism. The results showed that the effects of nano-TiO 2 depended on the organism, exposure time, crystal phase, and illumination conditions, and emphasized the need for a full characterization of nanoparticles and their behavior when studying nanotoxicity. © 2014 Springer Science+Business Media.168 Acra, A., Jurdi, M., Mu'Allem, H., Karahagopian, Y., Raffoul, Z., (1990) Water Disinfection by Solar Radiation: Assessment and Application, , http://almashriq.hiof.no/lebanon/600/610/614/solar-water/idrc/, International Development Research Centre. Cited 10 June 2012. Available from: (Internet)Aebi, H., Catalase in vitro (1984) Methods Enzymol, 105, pp. 121-126Allouni, Z.E., Hol, P.J., Cauqui, M.A., Gjerdet, N.R., Cimpan, M.R., Role of physicochemical characteristics in the uptake of TiO2 nanoparticles by fibroblasts (2012) Toxicol in Vitro, 26 (3), pp. 469-479Azevedo, E.B., Aquino Neto, F.R., Dezotti, M., TiO2-photocatalyzed degradation of phenol in saline media: Lumped kinetics, intermediates, and acute toxicity (2004) Appl Catal B Environ, 54, pp. 165-173Bagnyukova, T.V., Vasylkiv, O.Yu., Storey, K.B., Lushchak, V.I., Catalase inhibition by amino triazole induces oxidative stress in goldfish brain (2005) Brain Research, 1052 (2), pp. 180-186. , DOI 10.1016/j.brainres.2005.06.002, PII S0006899305008498Banerjee, S., Gopal, J., Muraleedharan, P., Tyagi, A.K., Raj, B., Physics and chemistry of photocatalytic titanium dioxide: Visualization of bactericidal activity using atomic force microscopy (2006) Current Science, 90 (10), pp. 1378-1383. , http://www.ias.ac.in/currsci/may252006/1378.pdfBarelds, H.P., (2010) The Uptake and Effects on Survival of Nano Silver and Nano Titanium Dioxide in Brine Shrimp (Artemia Nauplii), , http://dspace.library.uu.nl/handle/1874/44547, PhD thesis. Faculty of Veterinary Medicine Theses, Netherlands. Available fromBoyle, D., Al-Bairuty, G.A., Ramsden, C.S., Sloman, K.A., Henry, T.B., Handy, R.D., Subtle alterations in swimming speed distributions of rainbow trout exposed to titanium dioxide nanoparticles are associated with gill rather than brain injury (2013) Aquat Toxicol, 126, pp. 116-127Bradford, M., A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding (1976) Anal Biochem, 72, pp. 248-254Braydich-Stolle, L., Schaeublin, N., Murdock, R., Jiang, J., Biswas, P., Schlager, J., Hussain, S., Crystal structure mediates mode of cell death in TiO2 nanotoxicity (2009) J Nanopart Res, 11, pp. 1361-1374Calleja, M.C., Persoone, G., Geladi, P., Comparative acute toxicity of the first 50 Multicentre Evaluation of In Vitro Cytotoxicity chemicals to aquatic non-vertebrates (1994) Archives of Environmental Contamination and Toxicology, 26 (1), pp. 69-78Campos, B., Rivetti, C., Rosenkranz, P., Navas, J.M., Barata, C., Effects of nanoparticles of TiO2 on food depletion and life-history responses of Daphnia magna (2013) Aquat Toxicol, 130-131, pp. 174-183Chatterjee, D., Dasgupta, S., Visible light induced photocatalytic degradation of organic pollutants (2005) Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 6 (2-3), pp. 186-205. , DOI 10.1016/j.jphotochemrev.2005.09.001, PII S1389556705000316(1999) CIE Collection in Photobiology and Photochemistry [Internet], , http://www.cie.co.at/index.php/Publications/index.php?i_ca_id=410, Cited 7 Dec 2011. Available fromClément, L., Hurel, C., Marmier, N., Toxicity of TiO2 nanoparticles to cladocerans, algae, rotifers and plants - Effects of size and crystalline structure (2013) Chemosphere, 90, pp. 1083-1090Clemente, Z., Castro, V.L.S.S., Jonsson, C.M., Fraceto, L.F., Ecotoxicology of nano-TiO2 - An evaluation of its toxicity to organism of aquatic ecosystems (2012) IJER, 6 (1), pp. 33-50Clemente, Z., Castro, V.L., Feitosa, L.O., Lima, R., Jonsson, C.M., Maia, A.H., Fraceto, L.F., Fish exposure to nano-TiO2 under different experimental conditions: Methodological aspects for nanoecotoxicology investigations (2013) Sci Total Environ, 463-464, pp. 647-656(2009) How Do Anatase An Rutile Differ in Their Photocatalytic Activity. [Internet], , http://www.coatingsys.com/yahoo_site_admin/assets/docs/ How_do_anatase_and_rutile_differ_in_their_photocatalytic_activity.120225304.pdf, Cited 26 Feb 2013. Available fromCong, S., Xu, Y., Explaining the high photocatalytic activity of a mixed phase TiO 2: A combined effect of O2 and crystallinity (2012) J Phys Chem C, 115 (43), pp. 21161-21168Cui, Y., Gong, X., Duan, Y., Li, N., Hu, R., Liu, H., Hong, M., Hong, F., Hepatocyte apoptosis and its molecular mechanisms in mice caused by titanium dioxide nanoparticles (2010) J Hazard Mater, 183 (1-3), pp. 874-880Dattilo, A.M., Bracchini, L., Carlini, L., Loiselle, S., Rossi, C., Estimate of the effects of ultraviolet radiation on the mortality of Artemia franciscana in naupliar and adult stages (2005) International Journal of Biometeorology, 49 (6), pp. 388-395. , DOI 10.1007/s00484-005-0255-5Dvorak, P., Benova, K., Vitek, J., (2012) Alternative Biotest on Artemia Franciscana. Ecotoxicology, , http://www.intechopen.com/books/ecotoxicology/alternative-biotest-on- artemia-franciscana, Ghousia Begum (ed) ISBN: 978-953-51-0027-0. DOI:10.5772/29114. Available fromFederici, G., Shaw, B.J., Handy, R.D., Toxicity of titanium dioxide nanoparticles to rainbow trout (Oncorhynchus mykiss): Gill injury, oxidative stress, and other physiological effects (2007) Aquatic Toxicology, 84 (4), pp. 415-430. , DOI 10.1016/j.aquatox.2007.07.009, PII S0166445X0700272XFinnegan, M.P., Zhang, H., Banfield, J.F., Phase stability and transformation in titania nanoparticles in aqueous solutions dominated by surface energy (2007) Journal of Physical Chemistry C, 111 (5), pp. 1962-1968. , DOI 10.1021/jp063822cFouqueray, M., Dufils, B., Vollat, B., Chaurand, P., Botta, C., Abacci, K., Labille, J., Garric, J., Effects of aged TiO2 nanomaterial from sunscreen on Daphnia magna exposed by dietary route (2012) Environ Pollut, 163, pp. 55-61Fujishima, A., Zhang, X., Titanium dioxide photocatalysis: present situation and future approaches (2006) Comptes Rendus Chimie, 9 (5-6), pp. 750-760. , DOI 10.1016/j.crci.2005.02.055, PII S1631074805003036Gaya, U.I., Abdullah, A.H., Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: A review of fundamentals, progress and problems (2008) Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 9 (1), pp. 1-12. , DOI 10.1016/j.jphotochemrev.2007.12.003, PII S1389556708000300Gottfredsen, R.H., Larsen, U.G., Enghild, J.J., Petersen, S.V., Hydrogen peroxide induce modifications of human extracellular superoxide dismutase that results in enzyme inhibition (2013) Redox Biol, 1 (1), pp. 24-31Gottschalk, F., Sonderer, T., Scholz, R.W., Nowack, B., Modeled environmental concentrations of engineered nanomaterials (TiO2, ZnO, Ag, CNT, fullerenes) for different regions (2009) Environ Sci Technol, 43 (24), pp. 9216-9222Grassian, V.H., Adamcakova-Dodd, A., Pettibone, J.M., O'Shaughnessy, P.I., Thorne, P.S., Inflammatory response of mice to manufactured titanium dioxide nanoparticles: Comparison of size effects through different exposure routes (2007) Nanotoxicology, 1 (3), pp. 211-226. , DOI 10.1080/17435390701694295, PII 784702321Griffith, R.J., Luo, J., Gao, J., Bonzongo, J.C., Barber, D.S., Effects of particle composition and species on toxicity of metallic nanomaterials in aquatic organisms (2008) Environ Toxicol Chem, 27 (9), pp. 1972-1978Hanazato, T., Growth analysis of daphnia early juvenile stages as an alternative method to test the chronic effect of chemicals (1998) Chemosphere, 36 (8), pp. 1903-1909Handy, R.D., Cornelis, G., Fernandes, T., Ecotoxicity test methods for engineered nanomaterials: Practical experiences and recommendations from the bench (2012) Environ Toxicol Chem, 31 (1), pp. 15-31Hao, L., Wang, Z., Xing, B., Effect of sub-acute exposure to TiO2 nanoparticles on oxidative stress and histopathological changes in juvenile carp (Cyprinus carpio) (2009) J Environ Sci, 21 (10), pp. 1459-1466Heinlaan, M., Ivask, A., Blinova, I., Dubourguier, H.C., Kahru, A., Toxicity of nanosized and bulk ZnO, CuO and TiO to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus (2008) Chemosphere, 71, pp. 1308-1316Hund-Rinke, K., Simon, M., Ecotoxic effect of photocatalytic active nanoparticles (TiO2) on algae and daphnids (2006) Environ Sci Pollut R, 13, pp. 225-232Hussain, S., Bolanda, S., Baeza-Squiban, A., Hamel, R., Thomassen, L.C.J., Martens, J.A., Oxidative stress and proinflammatory effects of carbon black and titanium dioxide nanoparticles: Role of particle surface area and internalized amount (2009) Toxicology, 260, pp. 142-149Hwang, E.-S., Kim, G.-H., Biomarkers for oxidative stress status of DNA, lipids, and proteins in vitro and in vivo cancer research (2007) Toxicology, 229 (1-2), pp. 1-10. , DOI 10.1016/j.tox.2006.10.013, PII S0300483X06006196Keen, J.H., Habig, W.H., Jakoby, W.B., Mechanism for several activities of the glutathione S-transferase (1976) J Biol Chem, 251, pp. 6183-6188Keller, A.A., Wang, H., Zhou, D., Lenihan, H.S., Cherr, G., Stability and aggregation of metal oxide nanoparticles in natural aqueous matrices (2010) Environ Sci Technol, 44, pp. 1962-1967Kim, K.T., Klaine, S.J., Cho, J., Kim, S.H., Kim, S.D., Oxidative stress responses of Daphnia magna exposed to TiO2 nanoparticles according to size fraction (2010) Sci Total Environ, 408, pp. 2268-2272Kiser, M.A., Westerhoff, P., Bennt, W.Y., Pérez, R., Hristovsk, K., Titanium nanomaterial removal and release from wastewater treatment plants (2009) Environ Sci Technol, 43, pp. 6757-6763Kosmulski, M., pH-dependent surface charging and points of zero charge. IV. Update and new approach (2009) J Colloid Interface Sci, 337, pp. 439-448Kumagai, Y., Taira, J., Sagai, M., Apparent inhibition of superoxide dismutase activity in vitro by diesel exhaust particles (1995) Free Radic Biol Med, 18 (2), pp. 365-371Lardinois, O.M., Mestdagh, M.M., Rouxhet, P.G., Reversible inhibition and irreversible inactivation of catalase in presence of hydrogen peroxide (1996) Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology, 1295 (2), pp. 222-238. , DOI 10.1016/0167-4838(96)00043-XLee, S.W., Kim, S.M., Choi, J., Genotoxicity and ecotoxicity assays using the freshwater crustacean Daphnia magna and the larva o f the aquatic midge Chironomus riparius to screen the ecological risks of nanoparticle exposure (2009) Environ Toxicol Pharmacol, 28, pp. 86-91Li, M., Czymmek, K.J., Huang, C.P., Responses of Ceriodaphnia dubia to TiO2 and Al 2O3 nanoparticles: A dynamic nano-toxicity assessment of energy budget distribution (2011) J Hazard Mater, 187, pp. 502-508Lovern, S.B., Klaper, R., Daphnia magna mortality when exposed to titanium dioxide and fullerene (C60) nanoparticles (2006) Environmental Toxicology and Chemistry, 25 (4), pp. 1132-1137. , DOI 10.1897/05-278R.1Ma, H., Brennan, A., Diammond, S.A., Photocatalytic reactive oxygen species production and phototoxicity of titanium dioxide nanoparticles are dependent on the solar ultraviolet radiation spectrum (2012) Environ Toxicol Chem, 31 (9), pp. 2099-2107Ma, H., Brennan, A., Diamond, S.A., Phototoxicity of TiO2 nanoparticles under solar radiation to two aquatic species: Daphnia magna and Japanese medaka (2012) Environ Toxicol Chem, 31, pp. 1621-1629Marcone, G.P.S., Oliveira, A.C., Almeida, G., Umbuzeiro, G.A., Jardim, W.F., Ecotoxicity of TiO2 to Daphnia similis under irradiation (2012) J Hazard Mater, 211-212, pp. 436-442Östman, A., Böhmer, D.F., Regulation of receptor tyrosine kinase signaling by protein tyrosine phosphatases (2001) Trends Cell Biol, 11, pp. 258-266Pagnout, C., Jomini, S., Dadhwal, M., Caillet, C., Thomas, F., Bauda, P., Role of electrostatic interactions in the toxicity of titanium dioxide nanoparticles toward Escherichia coli (2012) Colloid Surface B, 92, pp. 315-321Palaniappan, P.L.R.M., Pramod, K.S., FTIR study of the effect of nTiO2 on the biochemical constituents of gill tissues of zebrafish (Danio rerio) (2010) Food Chem Toxicol, 48 (8-9), pp. 2337-2343Prazeres, J.N., Ferreira, C.V., Aoyama, H., Acid phosphatase activities during the germination of glycine max seeds (2004) Plant Physiol Biochem, 42, pp. 15-20Reeves, J.F., Davies, S.J., Dodd, N.J.F., Jha, A.N., Hydroxyl radicals (OH) are associated with titanium dioxide (TiO 2) nanoparticle-induced cytotoxicity and oxidative DNA damage in fish cells (2008) Mutat Res, 640 (1-2), pp. 113-122Robichaud, C.O., Uyar, A.E., Darby, M.R., Zucker, L.G., Wiesner, M.R., Estimates of upper bounds and trends in nano-TiO2 production as a basis for exposure assessment (2009) Environ Sci Technol, 43, pp. 4227-4233Rozenkranz, P.W., (2010) The Ecotoxicology of Nanoparticles in Daphnia Magna, , http://researchrepository.napier.ac.uk/3808/, PhD Thesis. Edinburgh Napier University, UK. Available fromScown, T.M., Aerle, R., Johnston, B.D., Cumberland, S., Lead, J.R., Owen, R., Tyler, C.R., High doses of intravenously administered titanium dioxide nanoparticles accumulate in the kidney of rainbow trout but with no observable impairment of renal function (2009) Toxicol Sci, 109 (2), pp. 372-380Seitz, F., Bundschuh, M., Rosenfeldt, R.R., Schulz, R., Nanoparticle toxicity in Daphnia magna reproduction studies: The importance of test design (2013) Aquat Toxicol, 126, pp. 163-168Sharma, V.K., Aggregation and toxicity of titanium dioxide nanoparticles in aquatic environment - A review (2009) J Environ Sci Health A, 44, pp. 1485-1495(2000) Enzymatic Assay of Glutathione Peroxidase (EC1.11.1.9). [Internet], , http://www.sigmaaldrich.com/etc/medialib/docs/Sigma/General_Information/ glutathione_peroxidase.Par.0001.File.tmp/glutathione_peroxidase.pdf, Cited 10 June 2013. Available from: Accessed 19 July 2013Sun, Y., Oberley, L.W., The inhibition of catalase by glutathione (1989) Free Radical Biology and Medicine, 7 (6), pp. 595-602. , DOI 10.1016/0891-5849(89)90140-8Sun, Q., Xu, Y., Evaluating intrinsic photocatalytic activities of anatase and autile TiO2 for organic degradation in water (2010) J Phys Chem C, 114 (44), pp. 18911-18918Toi, H.T., Ahyani, N., Sorgeloos, P., Bossier, P., Van Stappen, G., Manipulation of C/N ratio to stimulate the growth of bacteria as food for filter feeders in a laboratory culture system: A demonstration on artêmia (2013) World Aquaculture Society Meetings. Asian-Pacific AquacultureTong, T., Binh, C.T.T., Kelly, J.K., Gaillard, J.F., Gray, K.A., Cytotoxicity of commercial nano-TiO2 to Escherichia coli assessed by high-throughput screening: Effects of environmental factors (2013) Water Res, 47, pp. 2352-2362Ukeda, H., Maeda, S., Ishii, T., Sawamura, M., Spectrophotometric assay for superoxide dismutase based on tetrazolium salt 3'-{1-[(phenylamino)-carbonyl]-3,4-tetrazolium}-bis(4-methoxy-6- nitro)benzenesulfonic acid hydrate reduction by xanthine-xanthine oxidase (1997) Analytical Biochemistry, 251 (2), pp. 206-209. , DOI 10.1006/abio.1997.2273(1985) Standard Evaluation Procedure. Acute Toxicity Test for Estuarine and Marine Organisms, , U.S. Environmental Protection Agency (U.S.EPA) EPA-540/9-85-009. Hazard Evaluation Division. WashingtonVevers, W.F., Jha, A.N., Genotoxic and cytotoxic potential of titanium dioxide (TiO2) nanoparticles on fish cells in vitro (2008) Ecotoxicology, 17, pp. 410-420Wiench, K., Wohlleben, W., Hisgen, V., Radke, K., Salinas, E., Zok, S., Landsiedel, R., Acute and chronic effects of nanoand non-nano-scale TiO2 and ZnO particles on mobility and reproduction of the freshwater invertebrate Daphnia magna (2009) Chemosphere, 76 (10), pp. 1356-1365Xiong, S., George, S., Ji, Z., Lin, S., Yu, H., Damoiseaux, R., Size of TiO2 nanoparticles influences their phototoxicity: An in vitro investigation (2013) Arch Toxicol, 87, pp. 99-109Zhu, X., Chang, Y., Chen, Y., Toxicity and bioaccumulation of TiO2 nanoparticle aggregates in Daphnia magna (2010) Chemosphere, 78, pp. 209-215Zhu, X., Zhou, J., Cai, Z., The toxicity and oxidative stress of TiO2 nanoparticles in marine abalone (Haliotis diversicolor supertexta) (2011) Mar Pollut Bull, 63 (5-12), pp. 334-338