Brenntag UK Ltd and Wesco Aircraft EMEA Ltd have applied for a review of the continued use of chromium trioxide, sodium dichromate, potassium dichromate, and dichromium tris(chromate) in chemical conversion coating for the aerospace and defence industry and its supply chains. Chemical conversion coating is a process that introduces a chemical coating or changes the surface of the substrate to improve substrate properties such as corrosion resistance and adhesion promotion. The applicants have identified a shortlist of potentially suitable alternatives, but due to the complexity of design challenges, performance requirements, safety requirements, and regulatory controls that must be tested for each alternative, they are seeking a review period of 12 years. The proposed use involves the use of these chromates across approximately 80 sites in Great Britain, with annual tonnages ranging from 1 to 30 tonnes per year. The public consultation aims to gather feedback and opinions on the continued use of these chromates and potential alternatives.