Alkoxylation is performed in industry for producing non-ionic surfactants and polyethylene/polypropylene glycols. To this end, the most common type of reactor consists of a simple liquid-stirred reactor equipped sometimes with an external circulation loop to increase the reactor heat exchange capacity. More advanced chemical processes are now performed in Semi-Batch Venturi Loop reactors or in Spray Tower Loop Reactors, where the liquid phase is dispersed into the gaseous phase by means of recirculation loop. The three different reactor types used in the manufacture of ethoxylated products have been compared in terms of efficiency. However, few indications have been given in terms of accidental consequences, whose evaluation is mandatory when sound risk assessment of chemical processes is carried out. In this paper, the added risks due to the presence of the recirculation loop have been assessed by varying the operating conditions, either in terms of temperature or partial pressure of ethylene oxide (EO). The aim is, therefore, to rank the different technologies. (c) 2007 Elsevier Ltd. All rights reserved.