Identification of starting points for exposure assessment in the post-use phase of nanomaterial-containing products

Applying the precautionary principle to manufactured nanoparticles requires a full risk assessment throughout the life cycle of nanomaterial-containing products. We propose a pragmatic methodology for the systematic identification of knowledge gaps and of priority starting points for exposure assessment as one step of a risk assessment. Its feasibility and usefulness are demonstrated for the post-use phase of automobiles and paper products. These starting points include, for example, automobile recycling facilities or factories using large amounts of recovered paper. Our methodology is transferable to other life cycle phases and could also be applied to selected nanomaterials or to products still being developed.