title: Toxicity of silver and titanium dioxide nanoparticle suspensions to the aquatic invertebrate, Daphnia magna.
abstract: The purpose of this study was to investigate the 48 h acute toxicity of capped silver nanoparticles (AgNPs), and capped and uncapped titanium dioxide (nTiO₂) to Daphnia magna neonates. In addition, a 24 days chronic toxicity study was performed for D. magna exposed to uncapped nTiO₂ to evaluate effects on growth, reproduction and survival. The 48 h median lethal concentrations (LC₅₀) for carboxy-functionalized capped AgNPs and uncapped nTiO₂ were 2.75 μg/L and 7.75 mg/L, respectively. In contrast, no mortalities were observed for Daphnia exposed to carboxy-functionalized capped nTiO₂ at concentrations up to 30 mg/L. In the chronic toxicity experiment with uncapped nTiO₂, the growth, reproduction and survival of D. magna were significantly (p < 0.05) reduced at concentrations ranging from 4.5 to 7.5 mg/L. Growth and reproduction were reduced by 35 % and 93 %, respectively in the treatments at the highest uncapped nTiO₂ concentration (7.5 mg/L). Time to first reproduction was delayed by 2-3 days in D. magna and the test organisms produced only 1-2 broods over 24 days exposure to the highest concentration of uncapped nTiO₂. Overall, the results from the present study indicate that exposures of aquatic invertebrates to nanoparticles could have important ecological effects on lower trophic levels in aquatic ecosystems.
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada. pranabdas@trentu.ca
authors.forename: Pranab
authors.initials: P
authors.lastname: Das
authors.forename: Marguerite A
authors.initials: MA
authors.lastname: Xenopoulos
authors.forename: Chris D
authors.initials: CD
authors.lastname: Metcalfe
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D005659:Fungicides, Industrial / Q000633:toxicity; D008136:Longevity; D053768:Metal Nanoparticles / Q000633:toxicity*; D012098:Reproduction; D012834:Silver / Q000633:toxicity*; D013473:Sunscreening Agents / Q000633:toxicity; D013535:Suspensions / Q000633:toxicity; D014025:Titanium / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D005659:Fungicides, Industrial; D013473:Sunscreening Agents; D013535:Suspensions; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D012834:Silver; D014025:Titanium