Philip Demokritou

Associate Professor of Aerosol Physics

Department of Environmental Health

Department of Environmental Health

665 Huntington Avenue
Building 1, Room 1310B
Boston, Massachusetts 02115
Phone: 617.432.3481


Dr Demokritou’s research interests are primarily in the areas of Aerosol Science and Technology and Particle Health Effects, focusing on the sources, transport, and fate of particles in environmental and biological media. His diverse research activities include among others: 1) environmental naotechnology; 2) environmental health and safety of engineered nanoparticles and nanotechnology in general;  3) development of particle methods and systems for the physico-chemical and toxicological characterization of aerosols;  4) development of advanced numerical models using Computational Fluid Dynamics (CFD) to investigate transport and fade of air pollutants in the built environment; 5)  participation in particle health effect  studies both at national and  international levels (US, Chile, Athens- Greece, Kuwait, Cyprus).

The Center for Nanotechnology and Nanotoxicology at  the Harvard School of Public Health 

Dr Demokritou is currently the Director of the Center for Nanotechnology and Nanotoxicology at the Harvard T. H. Chan School of Public Health ( The center draws on decades of experience with environmental pollutants and the health effects of particles to address the unique environmental health and safety (EHS) concerns raised by engineered nanomaterials (ENM) & nanotechnology applications.

Center’s mission is to integrate exposure science and nanotoxicology risk assessment to facilitate science-based decision-making regarding nano-EHS.  In doing so, we are bringing together stakeholders including industry, academia, policy makers and the general public to maximize innovation and growth and minimize environmental and public health risks.

Why Nano?

Nanoparticles are integral to an increasing array of products, from sunscreen and cancer drugs to batteries and semiconductors.  However, the rapid expansion of this technology raises safety concerns, and calls for a better understanding of how nanomaterials affect biological and environmental systems.  Specifically, we need to learn more about the bio-nano interactions at cellular/molecular, organismal and environmental levels.  Since nanoparticles often display unexpected biological properties, we need to discover new toxicologic priciples to understand their potential risks.  This assessment is complicated by the fact that nanoparticles are able to penetrate tissues more deeply than larger particles, so careful evaluation of the dose and especially the anatomic distribution of nanoparticles is essential.  It is also important to examine species differences, and differences between in vitro versus in vivo exposure.  It is clearly imperative that the fields of nanotoxicology and risk assessment keep pace with nanotechnology and its expanding universe of applications.

New Technology Brings New Questions

How do we balance the potential of nanotechnology with the potential hazards from new and often inadequately characterized materials?  The rapid expansion of nanotechnology is a powerful scientific and economic force.  However, we need to match this progress with careful evaluation of the possible toxicity of nanomaterials and technologies.  This process can be made more efficient by searching for fundamental principles that govern biological responses to nanomaterials, rather than assessing the toxicity of specific nanomaterials one at a time.

How do we discover the rules of nanotoxicology?  A promising approach is to examine families of engineered and rigorously characterized particles and to study the role of such factors as particle size and shape, composition, and charge.  Our NanoCenter is generating these rational families of particles, holding some parameters constant while changing others systematically.  We bring together modern in vivo and in vitro toxicologic approaches to carry out the biologic evaluation of nanomaterials.  We also seek to advance methods needed to evaluate the safety of nanotechnology.

The NanoCenter combines excellence in material and exposure science with demonstrated skills in lung toxicology, pharmacokinetics, and biology.  By developing and utilizing industrially relevant ENM generation systems that enable us to control the properties of “real world” nanomaterial exposures, we will better understand how particle dynamics and physical and chemical parameters alter both pharmacokinetics and the extent of possible injury.  Correlations will be made between in vivo and in vitro methods, as well as between in vitro systems using rodent versus human cells. We will also study safer nanomaterial formulation concepts which can reduce the environmental and health implications of ENMs.

The NanoCenter will also develop and deploy a variety of exposure assessment technologies to define human exposures to nanomaterials during their full life cycle (manufacture, use, and disposal).  Using methods of lifecycle analysis (LCA), we will assess exposures to nanomaterials from “cradle to grave.”  Finally, all these data will be integrated using methods of risk assessment and physiologically based pharmacokinetic models.  The end result will be a science-based guide to appropriate standards for safety.  We neither want to create human health hazards nor do we want to erect unreasonable barriers to the creative uses of nanomaterials in industry and medicine.

Laboratory for Environmental Health Nanoscience (LEHNS)

Dr Demokritou is currently the Director of the LEHNS lab.  LEHNS research focuses on the implications and applications of engineered nanomaterials (ENMs) and nanotechnology   Our approach is to examine families of engineered and rigorously characterized ENMs and study the role of such factors as particle size, composition, charge and their bio-interactions. Recently, we have been conducting research on the interactions of industry relevant ENMs with physiologic fluids.  We bring together contemporary in vivo and in vitro toxicology as well as material and aerosol science approaches to assess nano-bio interactions and carry out the biologic evaluation of ENMs.

The LEHNS  Laboratory  is fully equipped with systems for the: generation of artificial monodisperse and polydisperse particles, as well as state of the art instrumentation for the real time measurement of the physico-chemical properties of particles from 2 nm to 20 microns.  Other activities of the laboratory include the design of particle-classification techniques such as impactors and speciation samplers and, performance evaluation of air sampling techniques. More than a dozen instruments and methods including a number of US patented methods have been developed over the years, for the physico-chemical, and biological characterization of particles.  These novel techniques have been used extensively by air pollution scientists and human exposure assessors in United States and worldwide.