Events & Media

The Bren School of Environmental Science & Management
at the University of California, Santa Barbara

Presents

A RESEARCH COLLOQUIUM

"Uptake Behaviors of Carbon Nanotubes in Ecological Receptors
Microbial Degradation, and Nanoecogenotoxicity"

Elijah J. Petersen
National Institute of Standards and Technology (NIST)
Biochemical Science Division

Monday, June 25, 2012
4:00 - 5:00 p.m.
Bren Hall 3526 (Pine Room)

"Research is emerging regarding the environmental fates and outcomes of engineered nanomaterials.
Dr. Petersen's timely talk addresses key issues in this new field.
— Patricia Holden, faculty host

Abstract
As a result of their unique properties, nanoparticles are being usedincreasingly in a wide range of consumer goods. Yet the environmental and human health risks of these materials are currently not well understood. Uptake and depuration behaviors of carbon nanotubes were tested using representative organisms from terrestrial, sediment, and aquatic ecosystems: earthworms (Eisenia foetida), oligochaetes (Lumbriculus variegatus), and water fleas (Daphnia magna), respectively. Earthworms and oligochaetes were not found to accumulate carbon nanotubes; however,daphnia were found to accumulate large masses of carbon nanotubes, and limited elimination was observed in the absence of feeding with algae. The biodistribution of the nanomaterials in daphnia was assessed using light and transmission electron microscopy. Degradation of carbon nanotubes by a bacterial consortium was also studied using radioactively labeled carbon nanotubes. The potential genotoxicity of nanomaterials was investigatedusing gas chromatography/mass spectrometry (GC/MS) with isotope dilution to quantitatively measure DNA damage lesions in plants. Radish seedlings were exposed to bulk CuO and CuO nanoparticles in the concentration range of 10 mg/L to 1000 mg/L. DNA was isolated from plant seedlings after exposure to the CuO particles for 6 days, and levels of DNA lesions 2,4-diamino-5-formamidopyrimidine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, and 8-hydroxyguanine were measured by GC/MS. Exposure to CuO nanoparticles at the same concentrations resulted in about a statistically significanttwo-fold increase in the levels of DNA lesions compared to controls. These results demonstrate that bulk CuO and CuO nanoparticles cause induction of DNA lesions in radish plants.

Biography
Elijah graduated from Case Western Reserve University in 2003, with BS and MS degrees in Civil Engineering and a BA in Psychology. He then received a PhD at the University of Michigan, using earthworms (Eisenia foetida) and sediment-dwelling oligochaetes (Lumbriculus variegatus) to study the ecological uptake and elimination behaviors of carbon nanotubes. He then received a Fulbright scholarship to do postdoctoral research at the University of Joensuu in Finland, where he studied the uptake and elimination of carbon nanotubes and fullerenes in Daphnia magna. Elijah joined NIST as a National Research Council postdoctoral research fellow from 2009-2010 and became a staff research scientist in 2010.

NOTE: Research colloquia are hosted by Bren faculty members and are generally high-level talks about research in a particular area of environmental science and management.

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