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Nano Specificity?

Is there actually a specific nanorisk?

Could the "nano" risk be limited to a set of identified dangers: irritating, corrosive, toxic, inflammable, or dangerous for the environment for example? What are the reasons for giving specific attention to this risk?

Some say that for many years chemists have been doing nanotechnology without knowing it. But we must distinguish between two categories of risks:

  • known risks, including explosion risks related to the Explosive Atmosphere (ATEX: 1999/92CE and 94/9CE directives) or the classic toxicity of a chemical in the macroscopic form,
  • potential or supposed risks, specifically related to the size and surface reactivity of the particles, as their shape facilitates cell penetration or their ability to fix and carry pollutants in the ecosystem.

Along with micrometric dust, nanometric dust particles present explosion and inflammation risks therefore they are combustible in air. Current data on risk explosion focus mainly on micrometric particles. A limited data are available for nanomaterials. In view of the trend of nanomaterials to agglomerate, it is difficult to extrapolate the results obtained with micropowders.

The pressure rise, the activation energy and the severity of an explosion have a tendency to increase with the decrease of the particle size. Nanomaterials seem to be more responsive, more explosive than bigger dust particles with the same chemical composition.

Brouillard et al. have shown, in the case of aluminum particles, the diameter of the particle influences the severity of the explosion in term of maximum pressure [J. Bouillard et al., Journal of Hazardous Materials 181 (2010) 873].

With the aim of preventing an explosion or a fire, the development of means of prevention and specific working methods may be useful. For example, it can be advantageous to consider the implementation of synthesis process or method of storing in a controlled atmosphere.

Maximum rate of pressure as a function of the specific aliminum particle surface area [J. Bouillard et al., Journal of Hazardous Materials 181 (2010) 873].