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College of Public Health

Environmental Health Alumnus Work with Nano-particles Highlighted

A native of the Himalayan country, Nepal, and an alumnus of East Tennessee State University, Dr. Lok R. Pokhrel began in May 2013 as a National Research Council (NRC) Post-doctoral Research Fellow at the USEPA Office of Research and Development (ORD), National Health and Environmental Effects Research Laboratory (NHEERL), Western Ecology Division, Corvallis, Oregon.

"With extensive research background on nanomaterials synthesis, characterization, fate and toxicity evaluation, as reflected by his peer-reviewed publications of research papers, reviews, including an editorial and several conference presentations, Lok brings needed expertise here at NHEERL to synthesize and characterize novel nanoparticles of silver, copper, titanium and cerium, to use them to study their fate and transport in soils and potential toxicity to terrestrial plants", said Dr. Christian Andersen, who is a Research Plant Physiologist and the subject area lead for investigating ecotoxicological effects of nanoparticles within ORD, and is Lok's supervisor. "Because of the many unknowns about what the physical-chemical properties of nanoparticles are that may impart toxic responses, Lok's training on statistically-based QSAR (quantitative structure activity relationship) modeling allows him to study various organic-coated nanoparticles to explore potential links between the unique physical-chemical characteristics that arise from the coating materials and physiological responses", said Dr. Paul Rygiewicz who is also Lok's supervisor and a Research Ecologist at the US EPA.

"The goal in developing QSARs for nanoparticles is to build models and databases that can be used to predict the potential toxicity of new particles, which are being synthesized by industries much faster than they can be tested for their possible toxicity. In addition, by linking specific particle attributes with toxicity, Lok's work will contribute to EPA's "green chemistry" efforts by providing information on how to synthesize new particles with characteristics that are safer to ecosystems", Dr. Mark Johnson said. Mark, NRC Adviser, is a Research Soil Scientist at the US EPA and also supervises Lok's research. "Our goal is to link Lok's synthesis, organic-coating, and toxicity work with data we will obtain at the Lawrence Berkeley National Lab synchrotron-based micro X-ray (3D) tomography facility that is coupled with Transmission Electron Microscopy. Undertaking this research will enable us to link the location of nanoparticles in tissues with any physiological responses measured and the knowledge gained will contribute to risk assessment of nanoparticles related to routes of exposure in terrestrial ecosystems", Mark added.

"It's been a blessing and a wonderful experience to work together with the US EPA scientists here at NHEERL, who not only offer scientific expertise but also bring policy perspectives with regard to science of the small (nanoparticles). Moreover, the summer this year has been amazing and the bounteous recreational activities available in Oregon have really kept me (and my family) engaged when I don't have much 'nano' to do", Lok said.

Drs. Brajesh Dubey and Phillp Scheuerman were Lok's major advisers for his PhD program at East Tennessee State University from where he graduated last spring with his degree in Environmental Nanotechnology. His dissertation was entitled "Evaluation of colloidal stability and ecotoxicity of metal-based nanoparticles in the aquatic and terrestrial systems". Lok has been presenting his research at local, national, and international conferences, and has received several awards, which reflects on the quality and importance of the work he has been doing over the years.

This article was taken from the "NRC Research Associateship Programs Newsletter."

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