The objective of this report is to compile available tools and models for the assessment of environmental exposure to manufactured nanomaterials, and to conduct an analysis of their applicability for use in regulatory exposure assessment. The report assesses the compiled models by providing a functional assessment, statistical analysis, and performance evaluation of each model. The functional assessment assesses the scope (underlying assumptions and foundational algorithms) and use of the tools; the statistical analysis quantifies parametric sensitivity and output uncertainty in models from those tools; the performance evaluation weighs the models against real scenarios (where applicable). Finally, the recommendations provide guidance on the applicability of the tools and models in regulatory assessments.