There has been a race to manufacture and use nanomaterials that has outstripped the available knowledge of the hazards associated with them. The WHO guidelines define nanomaterials of having at least one dimension less than 100 nm.
So far, there has been no specific long-term health effects seen in humans, but this may simply be because the nanomaterials are so new, and there has not been sufficient time for the critical exposure or incubation for the symptoms to appear. Where there is data from testing on animals, the data is limited, and the number of nanomaterials tested limited, and so some of the suggestions are based on extrapolation from the available but limited data.
Hence, the Guidelines are a collection of best practices including education and training and including specific materials where there is sufficient data to support the guidelines. The ideal is that the best practice is where the workers are never exposed to the nanomaterials at all. However. if this is impossible. then the next best practice is to minimize the exposure by including controls that may include worker participation in following a specific method of working with suitable personal protective clothing. Where a new nanomaterial is being used, the first step is to find if the material already has been classified, and if it has not, then to assign the material to a particular class according to the Globally Harmonized System of Classification and Labeling of Chemicals.
So, if any of you are considering using nanomaterials but have not yet completed a risk assessment, I include the location of the WHO (World Health Organization) Guidelines that you may find helpful.