title: Acute toxicity and accumulation of ZnO NPs in Ceriodaphnia dubia: Relative contributions of dissolved ions and particles.
abstract: Although the ecotoxicological effects of various metal oxide nanoparticles on aquatic organisms are being actively studied, the contributions of particles and dissolved ions towards toxicity are still not well understood. The current study aims to assess the contribution of ZnO NP(particle) and ZnO NP(ion) to the overall toxicity and accumulation of ZnO NP(total) in Ceriodaphnia dubia. The aggregation and dissolution kinetics were studied for three different sizes (50nm, 100nm and bulk) of ZnO particles at 0.05, 0.12, 0.25 and 0.5mg/L concentrations in the sterile lake water medium at 6, 12, 24, and 48h intervals. The 48h LC50 of ZnO NP(total) was found to be 0.431, 0.605 and 0.701mg/L for 50, 100nm and bulk particles exposure. However, LC50 of Zn(ion) was found to be 1.048, 1.343 and 2.046mg/L for dissolved ions from different sizes (50nm, 100nm, and bulk) of ZnO particles. At LC50 concentration, the accumulation of 90-95% was noted for the NP(particles) across the sizes employed, while only about 4-5% contribution was from the NP(ion) to the overall accumulation NP(total). The relative contribution of ZnO NP(ion) to overall toxicity and accumulation was found to be lesser than that of ZnO NP(particles) across the sizes used in the study.
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: M
authors.initials: M
authors.lastname: Bhuvaneshwari
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: V
authors.initials: V
authors.lastname: Iswarya
authors.affiliation: Department of Chemical Engineering, IIT Madras, India.
authors.forename: R
authors.initials: R
authors.lastname: Nagarajan
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: N
authors.initials: N
authors.lastname: Chandrasekaran
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India. Electronic address: amitav@vit.ac.in.
authors.forename: Amitava
authors.initials: A
authors.lastname: Mukherjee
mesh_terms: D000818:Animals; D033361:Cladocera / Q000187:drug effects* / Q000378:metabolism; D007477:Ions / Q000737:chemistry / Q000378:metabolism; D007928:Lethal Dose 50; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D007477:Ions; D014874:Water Pollutants, Chemical; D015034:Zinc Oxide
keywords: Accumulation; Acute toxicity; NP((ion)); NP((particles)); ZnO NPs