QSARs have been used for decades in the development of pharmaceuticals, where a drug is to be developed to achieve a particular biological action.  Our interest here is in the reverse use, where the chemical is known, and the biological action is to be predicted.  That too has been the focus of research for decades.  But here we are concerned specifically with their use for evaluating toxicity within the regulatory framework of REACH, and it is early days.  

In practice, the use of in silico methods by European industry within REACH is still limited.  There are  three key practical issues that can delay their use.  They are highly inter-connected.