OBOMod - Integrated modelling framework for residents' exposure to pesticides.

BACKGROUND: Pesticides can be transported from the site of application to homes via different routes and lead to exposure of residents, raising concerns regarding health effects. We built a deterministic model framework (OBOmod) to assess exposure of residents living near fields where pesticides are applied. METHODS: OBOmod connects five independent models operating on an hourly timescale and high spatial resolution (meters). Models include descriptions of spray drift, volatilization, atmospheric transport and dispersion, exchange between outdoor and indoor air and exchange between indoor air and dust. Fourteen bulb field applications under different weather conditions and comprising 12 pesticides were simulated. Each simulation included the first seven days after the application. The concentrations computed with OBOmod were compared with those measured in outdoor and indoor air and the amounts measured in indoor dust samples. RESULTS: Model evaluation indicated suitability of the developed framework to estimate outdoor and indoor air concentrations. For most pesticides, model accuracy was good. The framework explained about 30% to 95% of the temporal and spatial variability of air concentrations. For 20% of the simulations, the framework explained more than 35% of spatial variability of concentrations in dust. In general, OBOmod estimates remained within one order of magnitude from measured levels. Calculations showed that in addition to spray drift during application, volatilization from the field after spraying and pesticides in house dust are important routes for residents' exposure to pesticides. CONCLUSIONS: Our framework covers many processes needed to calculate exposure of residents to pesticides. The evaluation phase shows that, with the exception of the dust model, the framework can be used in support of health and epidemiological studies, and can serve as a tool to support development of regulations and policy making regarding pesticide use.

Pesticide Exposure of Residents Living Close to Agricultural Fields in the Netherlands: Protocol for an Observational Study.

BACKGROUND: Application of pesticides in the vicinity of homes has caused concern regarding possible health effects in residents living nearby. However, the high spatiotemporal variation of pesticide levels and lack of knowledge regarding the contribution of exposure routes greatly complicates exposure assessment approaches. OBJECTIVE: The objective of this paper was to describe the study protocol of a large exposure survey in the Netherlands assessing pesticide exposure of residents living close (<250 m) to agricultural fields; to better understand possible routes of exposure; to develop an integrative exposure model for residential exposure; and to describe lessons learned. METHODS: We performed an observational study involving residents living in the vicinity of agricultural fields and residents living more than 500 m away from any agricultural fields (control subjects). Residential exposures were measured both during a pesticide use period after a specific application and during the nonuse period for 7 and 2 days, respectively. We collected environmental samples (outdoor and indoor air, dust, and garden and field soils) and personal samples (urine and hand wipes). We also collected data on spraying applications as well as on home characteristics, participants' demographics, and food habits via questionnaires and diaries. Environmental samples were analyzed for 46 prioritized pesticides. Urine samples were analyzed for biomarkers of a subset of 5 pesticides. Alongside the field study, and by taking spray events and environmental data into account, we developed a modeling framework to estimate environmental exposure of residents to pesticides. RESULTS: Our study was conducted between 2016 and 2019. We assessed 96 homes and 192 participants, including 7 growers and 28 control subjects. We followed 14 pesticide applications, applying 20 active ingredients. We collected 4416 samples: 1018 air, 445 dust (224 vacuumed floor, 221 doormat), 265 soil (238 garden, 27 fields), 2485 urine, 112 hand wipes, and 91 tank mixtures. CONCLUSIONS: To our knowledge, this is the first study on residents' exposure to pesticides addressing all major nondietary exposure sources and routes (air, soil, dust). Our protocol provides insights on used sampling techniques, the wealth of data collected, developed methods, modeling framework, and lessons learned. Resources and data are open for future collaborations on this important topic. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/27883.

Determination of spray drift and buffer zones in 3D crops using the ISO standard and new LiDAR methodologies.

Spray drift generated in the application of plant protection products in tree crops (3D crops) is a major source of environmental contamination, with repercussions for human health and the environment. Spray drift contamination acquires greater relevance in the EU Southern Zone due to the crops structure and the weather conditions. Hence, there is a need to evaluate spray drift when treating the most representative 3D crops in this area. For this purpose, 4 spray drift tests, measuring airborne and sedimenting spray drift in accordance with ISO 22866:2005, were carried out for 4 different crops (peach, citrus, apple and grape) in orchards of the EU Southern Zone, using an air-blast sprayer equipped with standard (STN) and spray drift reduction (DRN) nozzle types. A further 3 tests were carried out to test a new methodology for the evaluation of spray drift in real field conditions using a LiDAR system, in which the spray drift generated by different sprayer and nozzle types was contrasted. The airborne spray drift potential reduction (DPRV) values, obtained following the ISO 22866:2005, were higher than those for sedimenting spray drift potential reduction (DPRH) (63.82%-94.42% vs. 39.75%-69.28%, respectively). For each crop and nozzle type combination, a sedimenting spray drift model was also developed and used to determine buffer zone width. The highest buffer width reduction (STN vs DRN) was obtained in peach (˃75%), while in grape, citrus and apple only 50% was reached. These results can be used as the starting point to determine buffer zone width in the countries of the EU Southern Zone depending on different environmental threshold values. Tests carried out using LiDAR system demonstrated high capacity and efficiency of this system and this newly defined methodology, allowing sprayer and nozzle types in real field conditions to be differentiated and classified.

Field experiment on spray drift: deposition and airborne drift during application to a winter wheat crop.

A field experiment was performed to evaluate various techniques for measuring spray deposition and airborne drift during spray application to a winter wheat crop. The application of a spraying agent containing the fluorescent dye Brilliant Sulfo Flavine by a conventional boom sprayer was done according to good agricultural practice. Deposition was measured by horizontal collectors in various arrangements in and outside the treated area. Airborne spray drift was measured both with a passive and an active air collecting system. Spray deposits on top of the treated canopy ranged between 68 and 71% of the applied dose and showed only small differences for various arrangements of the collectors. Furthermore, only small variations were measured within the various groups of collectors used for these arrangements. Generally, the highest spray deposition outside the treated area was measured close to the sprayed plot and was accompanied by a high variability of values, while a rapid decline of deposits was detected in more remote areas. Estimations of spray deposits with the IMAG Drift Calculator were in accordance with experimental findings only for areas located at a distance of 0.5-4.5 m from the last nozzle, while there was an overestimation of a factor of 4 at a distance of 2.0-3.0 m, thus revealing a high level of uncertainty of the estimation of deposition for short distances. Airborne spray drift measured by passive and active air collecting systems was approximately at the same level, when taking into consideration the collector efficiency of the woven nylon wire used as sampling material for the passive collecting system. The maximum value of total airborne spray drift for both spray applications (0.79% of the applied dose) was determined by the active collecting system. However, the comparatively high variability of measurements at various heights above the soil by active and passive collecting systems revealed need for further studies to elucidate the spatial pattern of airborne spray drift.

Estimated nationwide effects of pesticide spray drift on terrestrial habitats in the Netherlands.

This study estimated the potential effects of pesticide drift on terrestrial ecosystems outside target areas, for the Dutch situation. A series of field trials was conducted to estimate the effects of drift on different species groups at different distances from a treated plot for different categories of pesticide: herbicides, fungicides and insecticides. Measurements of the pesticide drift deposition resulting from standard agricultural practice were used to model deposition outside the treated area. These data were then combined with national statistics on cropland and pesticide use to assess the ecological effects of pesticide drift for the Netherlands as a whole. Three scenarios were considered: the recent past (1998), the present (2005) and an optimised scenario based on 'best available practice' (2010). In the recent past the impact of herbicide drift on sensitive life stages non-target vascular plants is estimated to have exceeded the 50% effect level on 59% of adjacent linear landscape elements such as ditch banks and hedgerows. For the impact of insecticides and fungicides on non-target insects and fungi this 50% effect figure was 29% and 28% of linear elements, respectively. In the present situation, with (narrow) unsprayed buffer zones and other measures in place, these percentages are down to 41% for herbicides, 21% for insecticides and 14% for fungicides. In the optimised scenario, with a greater buffer width of 2.25m for potatoes (compared to 1.50m in 2005) and 1m for other crops (compared to 0.25 and 0.5m in 2005) and 'best available practice', these percentages can be cut to zero. In natural areas located within farming regions the 10% effect level can be reduced from 31% of such areas (1998) to 0% under conditions of 'best available practice'.