Approved Abstracts

Trojan Horse: The effects of the association of microplastics with the bactericide triclosan in Uçá crab (Ucides Cordatus; Linnaeus, 1763).



Author(s): Nobre CR; Moreno BB; Alves AV; Rosa JL; Fontes MK; Campos BG; Silva LF; Duarte LFA; Abessa DMS; Choueri RB; Gusso-Choueri PK; Pereira CDS;
Presenter: Caio Rodrigues Nobre

Domestic sewage has been an important contributor of microplastics to aquatic environments. In these effluents, microparticles can interact with other contaminants, including those of emerging concern such as the bactericide triclosan. Through this association, microplastics become carriers of these contaminants and once they reach marine ecosystems, they can impact the biota. This study aims to evaluate the effects of the association of plastic particles with the bactericide triclosan, using the Uçá crab (Ucides cordatus) as a biological model. For this purpose, plastic polyethylene particles ranging in size from 100 to 250µm were contaminated with triclosan, after immersing them in a stock solution of 1mg/L. After a period of 48h of stirring, the solution was filtered and dried in a vacuum system. At the end of this process, the microparticles had their chemical characterization carried out and the bioassays were started. Specimens of U. cordatus were exposed to 3 treatments: seawater with DMSO (co-solvent used in triclosan solubilization) (C), virgin microplastic (250mg/L) (MP) and triclosan-contaminated microplastic (250mg/L) (MPT), with tissue samples being collected from 10 individuals in 3 days (T3) and in 7 days (T7). Biochemical and cellular biomarkers were quantified in gills, hepatopancreas, and muscle (EROD, DBF, GST, GPx, GSH, LPO, DNA strand-breaks, and ChE) and hemolymph (Neutral Red Retention Time). Water and MPs were sampled for chemical analysis at the end of the bioassays. Biomarker results were integrated using the biomarker response index (IBR). Triclosan-spiked microplastics showed a concentration of 10.59µg.g-1 at the beginning of the exposure and 0.22µg.g-1 at the end of the experiment. Triclosan in water (0.422µg.L-1) was found after exposure. The organisms exposed to triclosan-spiked microplastics showed greater changes in relation to the other treatments. In this treatment it was verified in the gills an increase in the activities of the enzymes EROD, GST, GSH, increased oxidative stress and DNA damage after 7 days of exposure. In the hepatopâncreas, an increase in GST in 3 days and a decrease in GSH was observed after 7 days of exposure. Greater cytotoxicity was observed in both exposure times in the hemolymph of organisms exposed to triclosan-contaminated microplastics. In the treatment containing only virgin microplastic, the individuals also showed alterations, but more subtle, and at 7 days, inhibition of EROD and GSH activity was observed in the hepatopancreas. The results of the IBR showed that the gills were the most damaged tissue, with greater alterations in the treatment with microplastic contaminated by triclosan in the different times of exposure. Gills are the organism’s first defense barrier acting in the biotransformation of organic contaminants. These results also show the “Trojan horse” effect, as the effects found in organisms are more associated with the substance carried by the microparticles, since no relevant effects were observed in animals exposed only to virgin microplastics. In the hepatopancreas, the highest index at 3 days of exposure was observed in the treatment containing microplastics contaminated with triclosan, however, after 7 days, the control treatment presented a higher index in relation to the other groups, demonstrating a return of homeostasis in these organisms. With these results, it is possible to affirm that microplastics are important carriers of substances of emerging concern in marine environments, contaminating the environmental matrices, generating adverse effects to organisms exposed to these stressors.

Financial Support: Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP (Processo: 2017/12193-9)


Keywords: Plastic Debris; Emerging Pollutants; Toxicity

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