Exposure assessment and safety considerations for working with engineered nanoparticles / Michael J. Ellenbecker, Sc.D., CIH, professor of occupational and environmental hygiene, director, Massachusetts Toxics use Reduction Institute, Department of Work Environment, College of Health Sciences, University of Massachusetts Lowell, One University Avenue, Lowell, MA, USA, Su-Jung (Candace) Tsai, Sc.D., assistant professor of occupational/environmental health and hygiene, School of Health Sciences, College of Health and Human Sciences, Purdue University, Delon and Elizabeth Hampton Hall of Civil Engineering, 550 Stadium Mall Drive, West Lafayette, IN, USA.