abstract
Humans are typically exposed to environmental contaminants' mixtures that result in different toxicity than exposure to the individual counterparts. Yet, the toxicology of chemical mixtures has been overlooked. This work aims at assessing and comparing viability and cell cycle of A549 cells after exposure to single and binary mixtures of: titanium dioxide nanoparticles (TiO2NP) 0.75-75 mg/L; cerium oxide nanoparticles (CeO2NP) 0.75-10 mu g/L; arsenic (As) 0.75-2.5 mg/L; and mercury (Hg) 5-100 mg/L. Viability was assessed through water-soluble tetrazolium (WST-1) and thiazolyl blue tetrazolium bromide (MTT) (24 h exposure) and clonogenic (seven-day exposure) assays. Cell cycle alterations were explored by flow cytometry. Viability was affected in a dose- and time-dependent manner. Prolonged exposure caused inhibition of cell proliferation even at low concentrations. Cell-cycle progression was affected by TiO2NP 75 mg/L, and As 0.75 and 2.5 mu g/L, increasing the cell proportion at G0/G1 phase. Combined exposure of TiO2NP or CeO2NP mitigated As adverse effects, increasing the cell surviving factor, but cell cycle alterations were still observed. Only CeO2NP co-exposure reduced Hg toxicity, translated in a decrease of cells in Sub-G1. Toxicity was diminished for both NPs co-exposure compared to its toxicity alone, but a marked toxicity for the highest concentrations was observed for longer exposures. These findings prove that joint toxicity of contaminants must not be disregarded.
keywords
TITANIUM-DIOXIDE NANOPARTICLES; IN-VITRO CYTOTOXICITY; TIO2 NANOPARTICLES; AQUEOUS-SOLUTIONS; CEO2 NANOPARTICLES; TOXICITY; REMOVAL; GENOTOXICITY; APOPTOSIS; RISK
subject category
Science & Technology - Other Topics; Materials Science
authors
Rosario, F; Bessa, MJ; Brandao, F; Costa, C; Lopes, CB; Estrada, AC; Tavares, DS; Teixeira, JP; Reis, AT
our authors
Ana Cristina Estrada
Junior Researcher
Cláudia Batista Lopes
Assistant Researcher
Daniela Soraia dos Santos Tavares
PhD Studentacknowledgements
Project NanoLegaTox (PTDC/SAU-PUB/29651/2017) was co-financed by COMPETE 2020, Portugal 2020 and European Union, through FEDER. A.T. Reis thanks the financial support of Fundacao para a Ciencia e Tecnologia through Grant SFRH/BPD/122112/2016. A. C. Estrada and C.B. Lopes are funded by national funds (OE), through FCT - Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. F. Brandao and M.J. Bessa are recipients of FCT fellowships SFRH/BD/101060/2014 and SFRH/BD/12046/2016.