There is scientific agreement that engineered nanomaterial (ENM) production, use and disposal lead to environmental release of ENM. However, very little is known on emissions of ENM to the environment. Currently, techniques are lacking to quantitatively monitor ENM emissions to and concentrations in the environment, and hence data on emissions and environmental concentrations are scarce. One of the few available studies reports the detection of nano-TiO2 in water leaching from exterior facades. Some experimental evidence is available on the release of nanosized materials from commercial textiles during washing. A handful of modeling studies have investigated ENM release to the environment. These studies modeled either the release of ENMs to the environment from ENM containing products during the consumer usage, or the release throughout the whole life cycle of ENM and ENM-containing products. Sewage sludge, wastewater, and waste incineration of products containing ENM were shown to be the major flows through which ENMs end up in the environment. However, reliable data are particularly lacking on release during ENM production and on the application amounts and empirical information on release coefficients for all life cycle stages and environmental compartments. Quantitative data linking occupational exposure measurements and ENM emission flows into the environment are almost completely missing. Besides knowing the amounts of ENM released into the environment, it is equally important to investigate in what form ENMs are released. First results show that much of the ENM released from products is present in matrix-bound form, but that also some fraction is released as single, dispersed nanoparticles.