The survey gathered information on a variety of types of methods and models, including those used to set priorities, to screen nanomaterials, to develop detailed assessments of exposure, and other types of methods or models. Methods or models suitable for prioritization often compare materials in a relative sense, but are not sufficient to quantitatively assess exposure to specific nanomaterials. In contrast, screening level methods or models are often used for semi-quantitative assessment of exposure to specific nanomaterials, but are biased towards developing conservative (protective) estimates which can be used to identify those exposures which are higher priority for further analysis. Finally, more detailed (higher tier) assessments are often developed where more accurate assessments are needed, for example, to initiate specific risk management action for major commodity chemicals. Analytical methods were also collected as a result of the survey, and these would fall in the “other” category.
