TiO2 NPs as "Trojan horse" in the bioaccumulation of personal care compounds in the clam Ruditapes philippinarum

Trabajo presentado en la SETAC Europe 27th Annual Meeting (Environmental Quality Through Transdisciplinary Collaboration), celebrada en Bruselas del 7 al 11 de mayo de 2017.In recent years, the use of personal care products (PCPs) has increased notably. This increase together with growing of human population in coastal areas has provoked a constant entrance of emerging pollutants into the aquatic environments. However, data about bioaccumulation and toxicity of PCPs in aquatic biota are scarce. In this research, the clam Ruditapes philippinarum has been considered as model organism. The aim of this work was to investigate the role of TiO2 nanoparticles in bioaccumulation of organic PCPs and the toxic responses of single and mixture exposure experiments using a battery of antioxidant enzymes (superoxide Oxidase, catalase, total gluthathione peroxidase, Se-dependent glutathione peroxidase and glutathione reductase ) , lipid peroxidation and DNA damage. In the experiment, four treatments, controls and ethanol controls were run in parallel. Two of the four treatments were single treatments, one of the treatment was 100 ppb of TiO2 in form of nanoparticles < 100 nm (TiO2 NPs) and the other one TiO2 in bulk form. The other two treatments were mixture treatment: a) 100 ppb of TiO2 NPs plus 10 ppb of a mix of organic PCPs and b) 100 ppb of TiO2 bulk plus 10 ppb of mix of organic PCPs. The organic PCPs selected were triclosan (antimicrobial), OTNE (fragrance) and benzophenone-3 and octocrylene (UV filters).. Bioaccumulation of inorganic compound such as TiO2 was almost immediate reaching steady stationary over exposure time; and depuration rate was low. Respect to organic compounds in mixtures, triclosan and benzophenone-3 accumulations were mediated by TiO2 and was driven by the size of the particles. TiO2 NPs seems to play a key role in the uptake of organic compounds (“a Trojan horse”), probably due to their high surface area, large pore volume and the presence of high affinity surface hydroxyl groups 1, plus their capacity to stabilize the occurrence of these organic compounds in the cell tissues. NPs provide potential route for the delivery of nanoparticle-associated toxic pollutants to sites where they would not normally reach them. Many NPs, including TiO2 NPs, have shown a tendency to adsorb other pollutants by binding transitional metal and organic pollutants; in addition they have showed the ability to internalize them into the body and cells. The joint action of the organic compound mix and any of the two forms of TiO2 provoked significant (p< 0.01) changes in the activity of antioxidant enzymes compared (EROD, SOD, CAT, T-GPx, Se-GPx, GST and GR). Despite of higher bioaccumulation of triclosan and benzophenone-3 in the TiO2 NPs mixture than TiO2 bulk mixture treatments, toxicity observed could be consequence of compound interactions instead of total bioaccumulation processes.This research has been funded by Junta de Andalucía (PE2011-RNM-7812 project).N