title: Toxicity profiling of water contextual zinc oxide, silver, and titanium dioxide nanoparticles in human oral and gastrointestinal cell systems.
abstract: Engineered nanoparticles (ENPs) are increasingly detected in water supply due to environmental release of ENPs as the by-products contained within the effluent of domestic and industrial run-off. The partial recycling of water laden with ENPs, albeit at ultra-low concentrations, may pose an uncharacterized threat to human health. In this study, we investigated the toxicity of three prevalent ENPs: zinc oxide, silver, and titanium dioxide over a wide range of concentrations that encompasses drinking water-relevant concentrations, to cellular systems representing oral and gastrointestinal tissues. Based on published in silico-predicted water-relevant ENPs concentration range from 100 pg/L to 100 µg/L, we detected no cytotoxicity to all the cellular systems. Significant cytotoxicity due to the NPs set in around 100 mg/L with decreasing extent of toxicity from zinc oxide to silver to titanium dioxide NPs. We also found that noncytotoxic zinc oxide NPs level of 10 mg/L could elevate the intracellular oxidative stress. The threshold concentrations of NPs that induced cytotoxic effect are at least two to five orders of magnitude higher than the permissible concentrations of the respective metals and metal oxides in drinking water. Based on these findings, the current estimated levels of NPs in potable water pose little cytotoxic threat to the human oral and gastrointestinal systems within our experimental boundaries.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: Marcella
authors.initials: M
authors.lastname: Giovanni
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: Chor Yong
authors.initials: CY
authors.lastname: Tay
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: Magdiel Inggrid
authors.initials: MI
authors.lastname: Setyawati
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: Jianping
authors.initials: J
authors.lastname: Xie
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, MD3 16 Medical Drive, Singapore, 117597, Singapore.|NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore.
authors.forename: Choon Nam
authors.initials: CN
authors.lastname: Ong
authors.affiliation: PUB, 40 Scotts Road, Singapore, 228231, Singapore.
authors.forename: Rongli
authors.initials: R
authors.lastname: Fan
authors.affiliation: PUB, 40 Scotts Road, Singapore, 228231, Singapore.
authors.forename: Junqi
authors.initials: J
authors.lastname: Yue
authors.affiliation: PUB, 40 Scotts Road, Singapore, 228231, Singapore.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: David Tai
authors.initials: DT
authors.lastname: Leong
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D060766:Drinking Water / Q000032:analysis*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D060766:Drinking Water; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D015034:Zinc Oxide
keywords: cell death; nanoparticles; nanotoxicity; oral-gastrointestinal; reactive oxygen species