Relative importance of vapour and spray exposures. The relative importance of the different routes of exposure for residents and bystanders depends on too many factors to be able to definitively say that any route is less important to consider in an exposure assessment than the others. The same boom sprayer scenario that was simulated in Fig 6 was repeated, but this time including vapour exposure to a low volatility pesticide in the central zone over a 500 x 500 m treated area. It can be seen in Figure 10 that the main contributors to the total exposure are inhaled vapour, direct dermal and indirect dermal exposure. Spray inhalation and ingestion contribute relatively low amounts. 12 Stakeholder input Stakeholder input was solicited at the start of the project at a workshop (Frewer, et al., 2011) and again when the first models were available in October 2013. Other stakeholder inputs, including from the Advisory Panel, were received over the course of the project. The stakeholder comments specific to work package 3, i.e. resident and bystander exposure models, are given in Appendix 8, together with the project responses to those comments. There were a significant number of comments and questions relating to the definitions of ‘resident’ and ‘bystander’, and of ‘acute’ and ‘longer term’ exposures. In order to reduce the likelihood of confusion arising from a lack of clarity, the models now relate to a single group of ‘residents and bystanders’ who are people who can be present for any length of time, adjacent to agricultural land that is treated with pesticides. There were also some comments relating to the routes of exposure that are included in long-term exposures. In the initial models made available for the October 2013 stakeholder workshop, it was assumed that, by definition, a single direct exposure to spray drift during an application event was an ‘acute’ exposure, and was not therefore included in the longer-term exposure calculation. In response to a direct question about this from the project team during the workshop, a number of stakeholders suggested that this was not reasonable, and therefore the revised models include direct exposure to spray drift in the longer-term exposure calculation. It is suggested that further discussion on this would be fruitful – the model now assumes that a single high exposure on one day is equivalent to a lower exposure repeated over a number of days, and this might not be a scientifically justifiable approach.
