[Are nanoparticles a new class of environmental toxin?]

In view of the toxic properties of nanoparticles, the authorities require them to be specifically identified and labeled This is in keeping with the spirit of the REACH legislation, which aims to protect consumers from products with inadequately documented risks for human health and the environment. However, the presence of natural nanoparticles in the environment must also be taken into account, together with the fact that, in any mixture of particles, the presence of a fraction of nanometer-sized particles cannot be ruled out, owing to the laws of statistical distribution. Moreover, while all toxic nanoparticles generate oxidative stress, their properties are not due solely to their size but also to their shape, surface texture and composition. Thus, nanoparticle toxicity should be considered specifically for each substance or group of substances, and the notion of intentional manufacture of nano-sized particles should be included in the impact assessment. The conditions of nanoparticle concentration/dilution and persistence, especially in water and sewage sludge, exemplified by silver and titanium oxide, suggest that nanoparticle behavior in the environment should be monitored.