Fall 2010, Issue 12

Environmental Contaminants: In Our Water—In Our Bodies

Kurt Pennell, PhD, PE, BCEE, joined the School of Engineering in 2009. He is professor and chair of the Department of Civil and Environmental Engineering. His current research focuses on the environmental fate and neurotoxicity of engineered nanomaterials and organic pollutants, groundwater remediation technologies, the role of persistent organic pollutants in Parkinson’s disease, and the influence of neuroactive steroids on seizure control.

Pennell received his PhD in soil and water science from the University of Florida. He worked as a postdoctoral fellow, then as an assistant research scientist, in the Department of Civil and Environmental Engineering at the University of Michigan before moving to the School of Civil and Environmental Engineering at the Georgia Institute of Technology, where he rose to the rank of full professor in 2007. He also held an adjunct appointment in the Department of Neurology at Emory University School of Medicine, where he completed four years of training as part of a mentored quantitative research career development award (K25) from the National Institutes of Health. Pennell continues to collaborate closely with his colleagues at Emory as an investigator in the NIH-funded Parkinson's Disease Collaborative Environmental Research Center at Emory.

Engineered nanomaterials are manufactured materials with at least one dimension in the range of 1–100 nanometers. (For comparison, a sheet of paper is about 100,000 nanometers thick.) Although engineered nanomaterials hold great promise, they may also hold great peril. Safety studies have not kept up with the pace of their production. "The EPA doesn't really have any regulations now," says Pennell. "They regulate based on the molecule; they don't regulate based on size. So they don't distinguish between colloidal size and nanosize, and that's the problem." Nanoparticles are currently found in many consumer products, including sunscreen, cosmetics, and clothing, and their production is estimated to increase dramatically over the next several decades.

Pennell and his research group characterize nanoparticles and organic pollutants such as polychlorinated biphenyls (PCBs) and pesticides in their lab in the Science and Technology Center (4 Colby Street, Medford). They determine the size and charge of the nanoparticles using dynamic light scattering (DLS), and study how different surface coatings, stabilizing agents, and media affect these characteristics. Pennell has two gas chromatography mass spectrometers (GCMSs) in his lab that are used to identify and quantify organic chemicals in soil, plasma and tissue samples. Studies of organic pollutant transport through subsoils, and modeling of experimental transport data, are done primarily in the Integrated Multiphase Environmental Systems (IMPES) Laboratory (200 College Avenue, Medford) in collaboration with other IMPES researchers. The IMPES lab is also the site for Pennell's studies of groundwater remediation technologies, including thermal treatment, surfactant flushing, and bioremediation.

Neurotoxicity studies are performed in collaboration with researchers at the Parkinson’s Disease Collaborative Environmental Research Center at Emory University. Preliminary studies suggest that the central nervous system is susceptible to damage from nanoparticles, especially from inhaled nanoparticles. Organic pollutants (PCBs and pesticides) have also been implicated in the acceleration of Parkinson's disease. Pennell's neurotoxicity studies involve metabolomics, which is the study of metabolite profiles of cellular chemical reactions. He primarily looks at metabolic profiles in response to chemical exposure, which is often manifested as elevated oxidative stress. "I look at PCBs and pesticides in plasma and human tissue, mostly brain tissue," he says. He is currently using a liquid chromatography mass spectrometer (LCMS) at Emory for this work but would be interested in using one at Tufts if possible. "I also do some studies looking at neurotoxicity of nanoparticles, looking at inflammation response, microglial response to nanoparticles," Pennell says. "For that, I do mostly the nanoparticle preparation, characterization, and quantification. I work with a colleague at Emory who does the actual cell culture or animal studies, using models of Parkinson's."

Pennell's studies of neuroactive steroids are conducted in collaboration with a research team at Brigham and Women's Hospital in Boston. Preliminary evidence suggests that levels of the sex steroid hormones estradiol and progesterone affect seizure activity in people with epilepsy; seizure frequency appears to increase with elevated estradiol/progesterone ratios and with declining or low progesterone levels. Pregnant women with epilepsy are a particularly vulnerable group, since the risks of seizures have to be balanced against the known teratogenic effects of anticonvulsant medications. Pennell is quantifying the levels of these hormones (and some metabolites) in serum samples from pregnant women with epilepsy. The results of this project could lead to the development of improved anticonvulsant therapies.

A recently awarded, $1.5M academic research infrastructure grant from the National Science Foundation to renovate the School of Engineering's Environmental Sustainability Laboratory will greatly enhance Tufts' capabilities to do research on emerging contaminants, including engineered nanomaterials, pharmaceuticals, personal care products, and pathogens. Pennell would like to find Tufts collaborators interested in any of the various aspects of his research, but especially in his work involving the neurotoxicity of nanomaterials and the role of organic pollutants in Parkinson’s disease.

For more information, please go to http://engineering.tufts.edu/cee/people/pennell.