Measured air concentrations of pesticides for the estimation of exposure to vapour in European risk assessments

Abstract

There is an identified need to revise the default air concentration values and assumptions applied in assessing vapour exposure in the risk assessment of bystanders and residents to plant protection products. To address this, we evaluated inhalation exposure via vapour using previously unpublished data from 29 field and wind tunnel studies. The database comprises 35 trials with 11 active ingredients covering a wide range of scenarios with respect to vapour pressure, crops, application rates and European regions. Of the 961 individual measurements, 634 were below the Limit of Detection (LOD), 282 were between the LOD and Limit of Quantification (LOQ) and only 45 (4.7%) were quantifiable. Ten individual non-normalized samples exceeded 0.1 μg/m³. Of the 81 first-day measurements after the application, 36 were <LOD, and quantifiable mean, 75th and 95th percentiles values were 0.114, 0.083, 0.552 μg/m³/kg AI applied/ha, respectively. No robust correlations between air concentration and temperature, leaf coverage, humidity, wind speed, and field size were identified; there is very limited correlation between air concentration and vapour pressure and Henry's constant in a subset of the data. These data indicate that potentially inhalable pesticide vapour within or near fields occurs only at very low concentrations in real scenarios.