title: Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna.
abstract: The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO(2) remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L(-1) nano-TiO(2), the (LC(50)) of Cu(2+) concentration observed to kill half the population, decreased from 111 μg L(-1) to 42 μg L(-1). Correspondingly, the level of metallothionein decreased from 135 μg g(-1) wet weight to 99 μg g(-1) wet weight at a Cu(2+) level of 100 μg L(-1). The copper was found to be adsorbed onto the nano-TiO(2), and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO(2) may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.
authors.affiliation: Department of Environmental Science and Engineering, School of Chemistry and Environment, Beihang University, Beijing 100191, China. fanwh@buaa.edu.cn
authors.forename: Wenhong
authors.initials: W
authors.lastname: Fan
authors.forename: Minming
authors.initials: M
authors.lastname: Cui
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Chuan
authors.initials: C
authors.lastname: Wang
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Shi
authors.forename: Cheng
authors.initials: C
authors.lastname: Tan
authors.forename: Xiuping
authors.initials: X
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D000818:Animals; D003300:Copper / Q000493:pharmacokinetics* / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects* / Q000378:metabolism; D007928:Lethal Dose 50; D053768:Metal Nanoparticles / Q000737:chemistry; D008668:Metallothionein / Q000378:metabolism; D014025:Titanium / Q000737:chemistry / Q000493:pharmacokinetics*; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics* / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D003300:Copper; D008668:Metallothionein; D014025:Titanium