2 Mar 2010 --- EFSA's Panel on Plant Protection Products and their Residues (PPR Panel) has launched an open consultation on a Draft Guidance on the Use of Probabilistic Methodology for Modelling Dietary Exposure to Pesticide Residues (Part one: single active substances exposure assessment). This guidance document proposes a methodology for performing probabilistic exposure assessment of single active substances in the contexts of MRL setting, enforcement actions and periodic reviews of monitoring data on actual exposures, as potential additional tool to deterministic methodologies.

Interested parties are invited to submit written comments by 10th May 2010. Please use exclusively the electronic template provided with the documents to submit comments and refer to the line and page numbers. Please note that comments submitted by e-mail or by post cannot be taken into account and that a submission will not be considered if it is:

• submitted after the deadline set out in the call
• presented in any form other than what is provided for in the instructions and template
• not related to the contents of the document
• contains complaints against institutions, personal accusations, irrelevant or offensive statements or material
• is related to policy or risk management aspects, which is out of the scope of EFSA's activity.

EFSA will assess all comments from interested parties which are submitted in line with the criteria above. The comments will be further considered by the EFSA PPR Panel and taken into consideration if found to be relevant.

According to EFSA, the assessment of dietary exposure to pesticide residues is a key step in process for authorisation of plant protection products and establishment of related maximum residue levels (MRLs) in plant commodities. This is required by Council Directive 91/414/EEC of 15 July 1991 concerning the placing on the market of plant protection products4, as well as by Regulation 396/2005 of the European Parliament and of the Council of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin5.

Currently, deterministic methods based on WHO guidelines6,7 are used for assessing dietary exposure. These methods provide an estimation of the exposure of one single virtual consumer and have the advantage of being of simple and fast to use.

In the recent years there has been growing interest internationally in the application of probabilistic techniques to the estimation of exposure to chemicals in food. In contrast with the deterministic methodology, these techniques allow the distribution of intakes8 amongst multiple individuals in a specified population to be estimated, taking into consideration the variability in food consumption between and within individuals and in occurrence of residues in food commodities.

The European Commission funded research on this methodology from 2000 to 2003 through the Monte Carlo project on the ‘Development, validation and application of stochastic modelling of human exposure to food chemicals and nutrients’ under the EC Fifth Framework Programme (Quality of Life Key Action 1 on Food Nutrition & Health).

Regarding pesticide residues in particular, the European Commission tendered a project aiming to develop draft guidelines on the use of probabilistic exposure assessment. This resulted in the publication of a report proposing ‘guidelines regarding probabilistic exposure assessment in the safety evaluation of pesticides in the EU market9’. To date, such guidelines have not been adopted for routine use in decision-making related to authorization of plant protection products or MRL-setting.

The PPR Panel is of the opinion that probabilistic methodology is a potentially useful tool for conducting refined consumer exposure assessments. In particular, in its opinion on cumulative risk assessment10, the PPR Panel stated that refined cumulative exposure assessments cannot be done without probabilistic methods and recommended that guidance for performing probabilistic exposure assessments should be developed.