Grantee Research Project Results
2007 Progress Report: Acute and Developmental Toxicity of Metal Oxide Nanoparticles in Fish and Frogs
EPA Grant Number: R832842Title: Acute and Developmental Toxicity of Metal Oxide Nanoparticles in Fish and Frogs
Investigators: Theodorakis, Christopher , Carraway, Elizabeth , Cobb, George
Institution: Southern Illinois University - Edwardsville , Towson University , Clemson University
Current Institution: Southern Illinois University - Edwardsville , Clemson University , Towson University
EPA Project Officer: Aja, Hayley
Project Period: October 24, 2005 through October 24, 2008
Project Period Covered by this Report: October 24, 2006 through October 24, 2007
Project Amount: $375,000
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: A Joint Research Solicitation - EPA, NSF, NIOSH (2005) RFA Text | Recipients Lists
Research Category: Human Health , Safer Chemicals , Nanotechnology
Objective:
The objectives of this research are to determine the environmental hazard associated with selected metal oxide nanoparticles (Fe2O3, ZnO, CuO, and TiO2), in terms of acute and chronic toxicity to fathead minnows (Pimephase promelas) and the African clawed frog (Xenopus laevis).
Progress Summary:
Toxicity tests
Xenopus laevis toxicity tests
For acute tests, eggs were collected and placed in small Petri dishes with 10mL of control or nanoparticle solution. The eggs that are collected are NF stage 8-11. The eggs that hatched were exposed to their respective dose for 96 hours. Test endpoints of survival, growth, and spinal column deformities were determined after 96 hours. Test vessels were kept in an incubator under constant temperature and a 12:12 light and dark cycle. The range-finding portion of the acute study used the following concentrations: control, 0.001, 0.01, 0.1, 1, 10, 100, 1000 mg/L. The control was a buffer solution formulated for the larvae. Each test concentration was run in duplicate with five eggs each. Mortality was defined as lack of response to physical stimuli. Deformities were defined in the Atlas of Abnormalities: A Guide for the Performance of FETAX 2nd edition by John Bantle. Test vessels were examine daily for dead and deformed tadpoles. Surviving larvae were euthanized with MS-222 and preserved in 10% neutral buffered formalin. Since the LC50 was >1000 mg/L in the range finding test, we used the same range for the definitive study. Each concentration for definitive toxicity was run in triplicate each containing 10 eggs. This study confirmed that the LC50 for each nanoparticle type was >1000 mg/L and that the EC50 for spinal column deformity was >1000 mg/L for TiO2, CuO, and Fe2O3.
The EC50 for spinal column deformity in solutions prepared from 40-100 nm ZnO was determined to be 4.2 mg/L in one trial and 8.2 mg/L in a repeat of that test. Some larvae were prepared for SEM analysis and other larvae are being digested to determine total metal concentration in tissue, described later.
Physical – chemical characteristics of nanoparticles
The particle sizes and characteristics of metal oxide nanoparticles were observed using scanning electron microscopy. Size and characteristics of the nanoparticles were determined prior to creating solutions. Water samples that will be collected are also being characterized. This will reveal the behavior, such as agglomeration, of metal oxide nanoparticles when exposed to the buffered FETAX solution and tadpoles.
All of the tested nanoparticles were received as fine powders. The mounting technique for nanoparticle powder is relatively simple and quick. Double sided conductive tape is placed on the small scanning electron microscope stub. A small amount of the nanoparticle will be placed on the tape. The excess nanoparticles are blown off with nitrogen gas. The goal is to remove nanoparticles that were not attached to the tape therefore creating a monolayer of nanoparticles on the stub. A small line of silver paint is applied to the tape and continued until the line is in contact with the stub. The nanoparticles were sputter coated for 30 seconds with a gold/palladium alloy with a Hummer V Sputter Coater. Ten nanometers of the alloy are applied every minute; therefore the nanoparticles were coated with approximately 5nm of alloy. Particles from colleagues at Clemson University were noticeably larger than the particles obtained from commercial vendors.
Future Activities:
Acute toxicity of ZnO, CuO, Cu0, TiO2, and Fe2O3 will be determined in fathead minnows. Chronic developmental toxicity of ZnO and TiO2 will be determined in clawed frogs.
Journal Articles:
No journal articles submitted with this report: View all 13 publications for this projectSupplemental Keywords:
Water, animal, ecosystem, aquatic, biology, Southwest, Midwest,, Health, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Biochemistry, Risk Assessment, nanochemistry, animal model, bioavailability, nanotechnology, nanomaterials, animal bioassays, nanoparticle toxicity, analysis of chemical exposureProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.