Regarding consumer habits and practices, the principle sources of data on food consumption are food consumption surveys, which are designed to be nationally representative datasets on food intake at the individual subject level. These typically use a food coding system specific to the country in question to describe the foods consumed by the population, and can have a number of days surveyed per subject typically varying from one to seven. Because they are designed to capture the variability in diets of consumers, they can readily be used to address the issue of aggregate exposure. While a large number of dietary surveys exist in different countries around the world, a central issue is the availability of the raw data, which for a few notable exceptions (US, UK, Netherlands) cannot be easily obtained. The European Food Safety Authority have taken most dietary surveys in Europe and recoded them into the FoodEx system and made summary statistics of food consumption available online, called the EFSA Comprehensive Database. While a useful source of exposure data, these do not provide the raw data which is required to do refined exposure analysis, both aggregate and cumulative (an increasingly important area for pesticides).
In terms of chemical concentration data, this typically depends on the domain. Regarding the nutrient composition of foods (which may be relevant for risk assessment), these typically accompany the dietary survey. For substances that are part of routine monitoring at a national level by control laboratories (e.g. pesticides and environmental contaminants) or examined by Total Diet Studies, there may be publicly available databases on chemical occurrence that provide representative levels of occurrence (such as the Pesticide Data Program in the US). However, for other food chemicals such as flavourings, additives, food contact materials, and several environmental contaminants, this information is lacking and is frequently required for regulatory purposes. One of the issues with providing refined data here is that is often proprietary, but concentration specific to level of an individual company is not always required – merely an indication of the range of use levels across the market.
Aggregate exposure is a well-established methodology within the food domain, as when considering dietary exposure to any chemical present in food the questions immediately presented are what different foods is the chemical present in and in what amounts. Performing an exposure assessment therefore requires knowledge of how foods are consumed in the diet and in what combinations and amounts across different demographics and geographies, as well as the level of chemical occurrence for those categories.