Table 2 Exclusion criteria to be applied to CF and WF data collected from literature to create SEL database level 1.

• Studies not reported in public databases.

• Internal not published calculations.

• Studies which do not properly specify objectives, methods, and results (Prisma protocol³⁰).

• CF studies not based on life cycle methodological approach.

• Studies which calculate WF as ‘consumed water’, ‘water use’ or simple ‘blue water’ and are not based on the methodology to estimate the water footprint as reported by Hoekstra et al.³¹

• CF studies where the functional unit is not expressed as kg CO₂ equ kg⁻¹ or litre of product or where it is not possible to derive the functional unit.

• WF studies where the functional unit is not expressed as litres of water/kg or litre of product or where it is not possible to derive the functional unit.

• CF studies with system boundary beyond the distribution centre of the final product and which do not report the contribution of different life cycle stages to the total CF.