Modelling Exposure by Spraying Activities—Status and Future Needs

Abstract

Spray applications enable a uniform distribution of substances on surfaces in a highly efficient manner, and thus can be found at workplaces as well as in consumer environments. A systematic literature review on modelling exposure by spraying activities has been conducted and status and further needs have been discussed with experts at a symposium. This review summarizes the current knowledge about models and their level of conservatism and accuracy. We found that extraction of relevant information on model performance for spraying from published studies and interpretation of model accuracy proved to be challenging, as the studies often accounted for only a small part of potential spray applications. To achieve a better quality of exposure estimates in the future, more systematic evaluation of models is beneficial, taking into account a representative variety of spray equipment and application patterns. Model predictions could be improved by more accurate consideration of variation in spray equipment. Inter-model harmonization with regard to spray input parameters and appropriate grouping of spray exposure situations is recommended. From a user perspective, a platform or database with information on different spraying equipment and techniques and agreed standard parameters for specific spraying scenarios from different regulations may be useful.

An assessment of the ECETOC TRA Consumer tool performance as a screening level tool

“…This is a result of the comparatively low cutoff of 10 Pa for the assumption of complete instantaneous release. Other authors have also indicated the conservative nature of the inhalation algorithm [7,13] Dermal route. The dermal algorithm is:…”

“…This effort is not intended to be a statistical assessment of TRA tool performance (indeed one of the findings of this and other studies is that consumer exposure data needed for exposure model evaluation are generally sparse [ 6 , 13 ]), but rather to consider the published findings of other tool users and also the results of recent studies specifically designed to address REACH exposure information requirements. Since the release of TRA, several downstream user sectors have published Specific Consumer Exposure Determinants (SCEDs) of values meant to be used to refine the TRA input parameters for specific scenarios when appropriate.…”

Exposure modelling in Europe: how to pave the road for the future as part of the European Exposure Science Strategy 2020–2030

“…Size of the aerosols in turn depends on the spraying device and many other factors, such as size reduction of droplets due to evaporation of volatile components, containment and spraying nozzle. In practice, accurate information on these parameters is often not available, because well documented spray exposure measurements are scarce [ 25 ]. Further research is required on new modelling approaches such as relative source strength [ 26 ], harmonisation between models regarding input parameters and identification of standard spray scenarios.…”

A New Model Algorithm for Estimating the Inhalation Exposure Resulting from the Spraying of (Semi)-Volatile Binary Liquid Mixtures (SprayEva)

“…Given the large number and variety of chemical substances present in spray products and the variability in use patterns, it is not possible to measure all potential exposures in different workplaces, but exposure modelling is imperative as well. This need has been met by the development of a variety of exposure models in research and regulatory communities [ 7 ]. Lists of models using different specific approaches to estimate exposure are also given in the BPR and REACH guidance [ 8 , 9 ] and by Hahn et al [ 7 ].…”

“…This need has been met by the development of a variety of exposure models in research and regulatory communities [ 7 ]. Lists of models using different specific approaches to estimate exposure are also given in the BPR and REACH guidance [ 8 , 9 ] and by Hahn et al [ 7 ]. These models are designed for different applications and different tiers of exposure assessment (i.e., screening to higher tiers), where a distinction is made between two sources of exposure: (1) primary exposure from the spray cloud and its overspray; (2) secondary exposure caused by the evaporation of substances from the treated surfaces.…”