February 20, 2014 by Sylwia Kosmala-Grzechnik


On the 3rd of December 2013, I attended a one-day workshop on technical aspects of human health non-dietary exposure assessment of biocide products. The workshop was held at the Chemicals Regulation Directorate in York. The key issues that must be taken into account while preparing product submissions under the Biocidal Products Regulation were presented with particular emphasis on three representative product types (PT), these being PT14 (Rodenticides), PT8 (Wood preservatives) and PT21 (Antifouling products). The workshop comprised a mixture of presentations and worked examples.

Topics covered in the workshop included:

  • Overview of the exposure assessment, including dossier structure
  • Different types of user, patterns of use, primary and secondary exposure scenarios
  • Selection of exposure models and associated guidance
  • The ‘risk envelope’ approach
  • Key factors affecting the risk assessment
  • Sources of information
  • Insight into EU groups and processes involved in the authorisation of biocidal products (including the role of the Human Exposure Expert Group [HEEG] and the Manual of Technical Agreement)
  • Recent developments in the area of human health risk assessments

The exposure assessment is a tiered process and there are many factors that need to be taken into consideration when undertaking human exposure assessment. In essence, it requires determination of the patterns of use, identification of the exposed population, establishing the pathways of exposure and quantification of potential chemical intake. As a first step, a worst case scenario is considered and maximum possible values are applied. If the conclusion is that a biocidal product is “of concern”, the assessment must be refined using additional data and reasoned arguments, based on expert judgment, in order to produce a more accurate exposure assessment.

During the workshop all currently available exposure models and relevant guidance documents were discussed. The ‘risk envelope’ approach was also presented. The procedure has been developed to reduce the workload when applying for an authorisation of a group of products that contain the same or similar active substances, and their patterns of use and user types are the same. This informal procedure can help to focus on the key issues of the risk assessment. However, as it is an informal procedure, applications are evaluated by the Competent Authority on a case-by-case basis and, therefore, it is crucial to present convincing and reasonable justification.

The experts also shared their personal experience in the area of human exposure assessment to date, with particular emphasis on those product types for which the team has had experience under the Biocidal Products Directive (BPD). They also highlighted a number of issues with applications for product authorisation that were not resolved at the Annex I evaluation programme under BPD and require further consideration at European level. Main areas of discussions so far have been assessment of automated dipping for wood preservatives and the new approach has been accepted at the TM III 2013. Also, human default parameters were widely discussed and the default values have been agreed at TM II 2013 (HEEG opinion on ‘Default human factor values for use in exposure assessments for biocidal products’).

After each presentation participants had an opportunity to verify their understanding of the topic in practice by calculating the exposure for products from different PTs based on data provided.

Overall, the workshop was packed with valuable information on various aspects of the human health exposure assessment of biocide products. At wca we believe it is important to actively participate in such conferences and workshops to ensure we remain up to date with all the latest developments and trends in this, and other, areas.