Food surveillance plans
Food surveillance plans, duplicate diet studies and biomonitoring
EU countries implement food surveillance plans in order to monitor contamination of the foods which are regulated according to EU directives and regulations, such as, the European Commission regulation (EC) No 1881/2006 setting maximum limits in foods for several contaminants. However, these surveillance plans focus on foods with existing maximum limits and do not cover the whole diet nor food contaminants which need to be evaluated by risk assessors. There are also difficulties to evaluate the representativeness of these monitoring tools. It is not generally possible to estimate the total exposure from food with the official monitoring. It is also not possible to cumulate some exposure data from Total Diet Studies with exposure data from official monitoring because official monitoring sample and analyse foods as produced or as sold and not as eaten. Moreover, surveillance plans do not measure concentrations at low level when they need to verify that maximum limits are not exceeded.
Furthermore in surveillance plans, foods are sampled and analysed as produced or as purchased in order to evaluate the proportion of the foods with a contamination level lower than the maximum permitted level. Therefore, this approach does not allow assessment of the real exposure and the risk for the consumers because the food contamination can sometimes increase or decrease during storage or preparation in the home. For instance, heating food can produce acrylamide, furan or other toxic substances. In addition, the levels of some contaminants such as nitrates can decrease or increase during storage or heating (Tamme et al, 2009). For all of these reasons, surveillance plans cannot be the main source of exposure assessment data for risk assessment at the international level. Because TDS rely on the chemical analysis of food as eaten and not as produced, there is no need to apply dilution or concentration factors to assess the realistic exposure.
Duplicate diet studies are based on analysis of duplicated meals taken by a small sample of individuals (less than 300). All the different foods eaten are not analysed separately. Meals are often mixed and analysed as a whole. The use of duplicate diet studies is to assess between individuals variability of exposure without knowing the contribution of the different foods to the exposure. The limited size of the sample of participants is linked to the participation burden.
Another source of information for exposure assessment is biomonitoring, which is often based on blood or urine sample analysis. Nevertheless, it evaluates exposure from a multiplicity of sources other than food. Biomonitoring studies are very important when needing to describe trends of exposure and to compare exposure between countries. However, these studies do not always provide external exposure estimates because of the lack of biomarkers and Toxicokinetics knowledge. To date, the risk assessment of food related contaminants mainly relies in the comparison of external exposures with toxicological reference values. This is the reason why biomonitoring studies could not replace external exposure studies like TDS. Additionally, external exposure studies are the only way to estimate the contribution of different food categories to total exposure of a contaminant. This last example is essential for risk management, for instance for setting maximum limits for contaminants in food.