79 Combination of Screening and Higher tier Modelling Approaches for Estimating Inhalation Exposure During Spray Applications

Abstract Sprays are used in workplace as well as in consumer environments. Although spraying has several advantages such as uniform distribution of substances on surfaces in a highly efficient manner it is often prone to high inhalation burden which has to be quantified for adequate risk assessments. There are occupational exposure models with different degree of complexity available that are applied for spray applications. In the presentation we report on an effort to create an overall model for estimating inhalation exposure caused by spray applications by re-analyzing, refining and integrating three already existing models into a 2-level tiered approach. The single models used in this context are a 1- and 2-box mass balance model (Tier 1), Spray Expo and a newly developed binary system model (Tier 2). The Tier 1 level models are used for an initial assessment generally designed to deliver conservative results. Only if product safety cannot be derived from these results higher level models are used which are expected to generate results with a lower degree of conservatism. These higher level models are based on the solution of transport equation in space and time for the ingredients, taking into account the complex evaporation kinetics of interacting binary systems and consider the relevant sources in the spraying and post-spraying phase such as evaporation from droplets and treated surfaces. The presentation will contain the description of the overall model, results on plausibility and sensitivity, and the comparison with measured data.