REACH also addresses the continued use of chemical "substances of very high concern" (SVHC) because of their potential negative impacts on human health or the environment. From 1 June 2011, the European Chemicals Agency must be notified of the presence of SVHCs in articles if the total quantity used is more than one tonne per year and the SVHC is present at more than 0.1% of the mass of the object. Some uses of SVHCs may be subject to prior authorisation from the European Chemicals Agency, and applicants for authorisation will have to include plans to replace the use of the SVHC with a safer alternative (or, if no safer alternative exists, the applicant must work to find one) - known as "substitution". , there are 168 SVHCs on the candidate list for authorization.