6. Should there be variations or exceptions to the working definition?
The 1nm-100nm lower and upper limits both need careful interpretation in some cases. For example, the lower limit of 1nm implies that many molecules would be classified as nanomaterials. These should be excluded, but not in every case. The exceptions are some specific chemicals such as fullerenes. Tubes and fibres which would fall outside this definition because they are less than 1nm across may also need to be included.
At the other end of the scale, the upper limit of 100nm could lead to excluding some multi-component nanomaterials used in medicine and cosmetics. In such cases, the size of the components may need to be taken into account.