Health implications of nanoparticles

Nanoparticles are increasingly used in a wide range of applications in science, technology and medicine. Since they are produced for specific purposes which cannot be met by larger particles and bulk material they are likely to be highly reactive, in particular, with biological systems. On the other hand a large body of know-how in environmental sciences is available from toxicological effects of ultrafine particles (smaller than 100 nm in size) after inhalation. Since nanoparticles feature similar reactivity as ultrafine particles a sustainable development of new emerging nanoparticles is required. This paper gives a brief review on the dosimetry of nanoparticles, including deposition in the various regions of the respiratory tract and systemic translocation and uptake in secondary target organs, epidemiologic associations with health effects and toxicology of inhaled nanoparticles. General principles and current paradigms to explain for the specific behaviour of nanoparticles in toxicology are discussed. With that respect we consider nanoparticles to be in the range from 1 to 2 nm (clusters of atoms/molecules) to particles that are smaller than 100 nm at least in one dimension. Since the evidence for health risks of ultrafine and nanoparticles after inhalation has been increasing over the last decade, the paper attempts to extrapolate these findings and principles observed in particle inhalation toxicology into recommendations for an integrated concept of risk assessment of nanoparticles for a broad range of use in science, technology and medicine.