The World Health Organization’s (WHO) International Program on Chemical Safety (IPCS) published a draft Environmental Health Criteria (EHC) Document, Principles and Methods to Assess the Risk of Immunotoxicity Associated with Exposure to Nanomaterials. According to IPCS, the target audience is risk assessors in a regulatory setting, researchers, and industry that needs to provide the data for assessment. The draft EHC Document states that recent reports have identified engineered nanomaterials as potential stimulants of immune response that may culminate in eventual immunotoxicity. The draft EHC Document acknowledges that there are no validated methodology available to assess the immunotoxicity of nanomaterials, and outlines several assays that are conventionally used to assess chemical-induced immunotoxicity that may be compliant with nanomaterial testing. In general terms, according to the draft EHC Document, risk assessment of nanomaterials should follow the risk assessment paradigm for chemicals — hazard identification, hazard characterization, exposure assessment, and risk characterization. The draft EHC Document states that the design to perform risk analysis should be done on a case-by-case basis, flexibly including the components most appropriate for the material and its proposed use. The draft EHC Document includes case studies for carbon nanotubes and silver nanoparticles. Comments are due July 21, 2017.