Internal report on the harmonisation of dilution factors to be used in the assessment of dietary exposure

The Scientific Panels of EFSA perform risk assessment for a wide variety of chemical substances. One of the crucial steps of this process is the dietary exposure assessment where a number of assumptions can be applied at its various steps. Occurrence data received by EFSA are often expressed in different formats, which leads to the use of dilution factors in order to match the occurrence values reported in dry samples with their respective liquid consumption amounts (or vice versa). In its previous scientific outputs, EFSA assumed several dilution factors on a case by case approach. As a consequence of a lack of guidance or reference, different factors were used for the same food groups in various opinions. Considering exposure assessment as a critical component of risk assessment, the present report discusses and provides recommendations on the most appropriate dilution factors to be considered when matching food consumption and occurrence data. Sources were consulted and reviewed, in parallel with the analysis of recommendations described on labels by manufacturers. Where limited information was available, an adequate factor was derived by balancing the pertinence of the information extracted and its historical use by EFSA in previous scientific outputs. The factors suggested in this document represent a step forward in the harmonisation and standardisation of the methodologies used in EFSA. Harmonising the use of the default dilution factors, instead of a case-by-case approach, will improve the quality and validity of EFSA’s scientific outputs.