The appropriate assessment of the human health hazards of complex inorganic materials is required to ensure their adequate risk management. This requires that the collection of data fulfils information requirements outlined in different chemicals management systems and identifies gaps in the knowledge of the material. Toxicity data on complex inorganic materials allowing to fulfil these human health information requirements and derive dose–responses/effect levels are usually scarce. Although testing could be theoretically envisaged to complete data gaps, the number of complex inorganic materials to be assessed would have significant implications for animal welfare and represent a disproportionate burden. For some materials like the Unknown or Variable composition, Complex reaction products or Biological materials (UVCBs), the variability will also prevent selecting a representative sample. The assessment will therefore often be based on the constituents of the complex materials. This chapter will discuss some alternatives to collect hazard information, like grouping and read-across of complex materials, the use of data on the constituents, and present recent refinements, illustrated with examples that can be of help.