Characterizing the effects of titanium dioxide and silver nanoparticles released from painted surfaces due to weathering on zebrafish (Danio rerio)

Abstract

Silver (nAg) and titanium dioxide nanoparticles (nTiO₂) are common engineered nanoparticles (ENPs) added into paint for their antimicrobial and whitening properties, respectively. Weathering of outdoor painted surfaces can release such ENPs, though little is known about the potential effects of released ENPs on aquatic species. The objective of this study was to characterize the toxicity of nAg and nTiO₂ released from painted panels using fish liver cells (CRL2643) and zebrafish embryos (OECD 236 embryotoxicity test). Cells and embryos were exposed to suspensions of pristine nAg or nTiO₂, panels (unpainted or painted with nAg or nTiO₂) or base paint, after sonication. Cell viability and gene expression were assessed using resazurin assay and qPCR, respectively, while embryo mortality and deformities were scored visually via microscopic examination. In the cell studies, both paint-released nanoparticles did not affect viability, but paint-released nAg resulted in differential expression of a few genes including gclc and ncf1. In embryos, paint-released nAg increased mortality and incidence of deformities, whereas paint-released nTiO₂ resulted in differential expression of several genes including gclc, ncf1, txnrd1, gpx1b, and cyp1c1 but without major phenotypic abnormalities. Comparing the two types of exposures, paint-released exposures affected both molecular (gene expression) and apical (embryotoxicity) endpoints, while pristine exposures affected the expression of some genes but had no apical effects. The differing effects of paint-released and pristine nanoparticle exposures suggest that further research is needed to further understand how paint coatings (and the products of their weathering and aging) may influence nanoparticle toxicity to aquatic organisms.

Keywords:

• Nanotoxicology
• nanomaterials
• in vitro tests
• aquatic toxicology
• nTiO2 in paint
• nAg in paint
• weathering

Acknowledgments

The authors acknowledge financial support from the McGill Sustainability Systems Initiative (MSSI), Environment and Climate Change Canada, Cascades Inc., as well as the NSERC Discovery Grants program (award RGPIN-2019-04842. N.B.), NSERC (award RGPIN-2016-05022 and RGPAS-492998-16, S.G.) and the NSERC Strategic Project Grants program (award STPGP 479090—2015, N. B. and S. G.). The authors also thank Jenny Eng for logistical assistance, and Hugo Marchand, Emily Boulanger, and Sylvie Dasne for assistance with zebrafish husbandry.

Disclosure statement

No potential conflict of interest was reported by the author(s).