title: Developmental phytotoxicity of metal oxide nanoparticles to Arabidopsis thaliana.
abstract: Phytotoxicity is an important consideration to understand the potential environmental impacts of manufactured nanomaterials. Here, we report on the effects of four metal oxide nanoparticles, aluminum oxide (nAl(2)O(3)), silicon dioxide (nSiO(2)), magnetite (nFe(3)O(4)), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). Three toxicity indicators (seed germination, root elongation, and number of leaves) were quantified following exposure to each nanoparticle at three concentrations: 400, 2,000, and 4,000 mg/L. Among these particles, nZnO was most phytotoxic, followed by nFe(3)O(4), nSiO(2), and nAl(2)O(3), which was not toxic. Consequently, nZnO was further studied to discern the importance of particle size and zinc dissolution as toxicity determinants. Soluble zinc concentrations in nanoparticle suspensions were 33-fold lower than the minimum inhibitory concentration of dissolved zinc salt (ZnCl(2)), indicating that zinc dissolution could not solely account for the observed toxicity. Inhibition of seed germination by ZnO depended on particle size, with nanoparticles exerting higher toxicity than larger (micron-sized) particles at equivalent concentrations. Overall, this study shows that direct exposure to nanoparticles significantly contributed to phytotoxicity and underscores the need for eco-responsible disposal of wastes and sludge containing metal oxide nanoparticles.
authors.affiliation: Department of Civil and Environmental Engineering, Rice University, MS-317, Houston, Texas 77005, USA.
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Lee
authors.forename: Shaily
authors.initials: S
authors.lastname: Mahendra
authors.forename: Katherine
authors.initials: K
authors.lastname: Zodrow
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Yu-Chang
authors.initials: YC
authors.lastname: Tsai
authors.forename: Janet
authors.initials: J
authors.lastname: Braam
authors.forename: Pedro J J
authors.initials: PJ
authors.lastname: Alvarez
mesh_terms: D000537:Aluminum Oxide / Q000633:toxicity; D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development; D004785:Environmental Pollutants / Q000633:toxicity*; D052203:Ferrosoferric Oxide / Q000633:toxicity; D018525:Germination / Q000187:drug effects; D053768:Metal Nanoparticles / Q000633:toxicity*; D012822:Silicon Dioxide / Q000633:toxicity; D015034:Zinc Oxide / Q000633:toxicity
chemical_list: D004785:Environmental Pollutants; D012822:Silicon Dioxide; D000537:Aluminum Oxide; D015034:Zinc Oxide; D052203:Ferrosoferric Oxide