title: The zerovalent iron nanoparticle causes higher developmental toxicity than its oxidation products in early life stages of medaka fish.
abstract: Nanoscale zerovalent iron (nZVI)-mediated oxidation reaction is increasingly being used for enhanced treatment of water or wastewater processes; however, the fate and eco-toxicological effects of nZVI in the surface aquifer remain unclear. We investigated bioaccumulation and lethal-to-sublethal toxic effects on early life development of Japanese medaka (Oryzias latipes) with 7-day exposure to 25-200 mg/L of well-characterized solutions containing carboxymethyl cellulose (CMC)-stabilized nZVI (CMC-nZVI), nanoscale iron oxide (nFe3O4) or ferrous ion [Fe(II)aq]. The CMC-nZVI solution had the greatest acute mortality and developmental toxic effects in embryos, with lesser and the least effects with Fe(II)aq and nFe3O4. The toxicity of CMC-nZVI was ascribed to its high reactivity in the oxygenic solution, which led to a combination of hypoxia and production of reactive oxygen species (ROS) and Fe(II)aq. nFe3O4 (50-100 mg/L) was more bioavailable to embryos and bioaccmulative in hatchlings than suspended CMC-nZVI. The antioxidant balance was differentially altered by induced intracellular ROS in hatchlings with all 3 iron species. We revealed causal toxic effects of nZVI and its oxidized products in early life stages of medaka fish using different organizational levels of biomarker assays. The toxicity results implicate a potential eco-toxicological impact of nZVI on the aquatic environment.
authors.affiliation: Department of Agricultural Chemistry, College of Bio-Resources and Agriculture, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan. chenpj@ntu.edu.tw
authors.forename: Pei-Jen
authors.initials: PJ
authors.lastname: Chen
authors.forename: Wan-Lin
authors.initials: WL
authors.lastname: Wu
authors.forename: Kevin Chia-Wen
authors.initials: KC
authors.lastname: Wu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D002374:Catalase / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects; D047108:Embryonic Development / Q000187:drug effects*; D005980:Glutathione Reductase / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D007477:Ions; D007501:Iron / Q000633:toxicity*; D008018:Life Cycle Stages / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D009990:Oryzias / Q000196:embryology*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D007477:Ions; D017382:Reactive Oxygen Species; D007501:Iron; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D002266:Carboxymethylcellulose Sodium