Flack Sheila L, Ledson Timothy Mark, Ramanarayanan Tharacad S
J Agric Saf Health. 2019 Apr 16;25(2):91-103. doi: 10.13031/jash.13065.
Potential inhalation exposure of agricultural workers and bystanders to aerosolized particles emitted by typical agricultural spray nozzles is influenced by the particle size distribution (PSD) of the spray. However, inhalation risk assessments do not currently factor in the human-relevant PSD that may be inhaled during pesticide handling activities. This study was conducted to characterize the PSD of aerosols collected with OSHA Versatile Sampler (OVS) tubes, which are monitoring devices commonly used for inhalation risk assessment in worker exposure studies. An Oxford Lasers N60V particle size analyzer was used for characterizing the spray PSD emitted from various agricultural nozzles. Side-by-side air sampling with OVS tubes and Respicon TM particle samplers was conducted to characterize the size distribution of aerosols collected on the OVS tubes during spraying of a diluted chlorothalonil formulation. Based on this comparison, OVS tubes captured the inhalable fraction (mass median diameter (D50) = 100 μm), with approximately 40% of the total inhalation concentration contributing to systemic exposure (D50 = 10 μm) regardless of nozzle spray quality. In addition, nozzles with fine and medium spray produced higher airborne concentrations compared to nozzles with coarse spray. Thus, the use of modern low-drift nozzles (e.g., air-induction nozzles) that emit larger spray droplets can substantially reduce the airborne concentration levels within inhalable particle size fractions. While the concentrations within these airway fractions (e.g., respirable, thoracic, inhalable) increased from extremely coarse to very fine spray nozzles, the relative proportion of each fraction within the total inhalable concentration remained constant regardless of spray quality or nozzle type. Such information on the PSD of pesticide applications can be used to refine inhalation risk assessments for agricultural workers and bystanders.
农业工人和旁观者吸入典型农业喷雾喷嘴喷出的雾化颗粒的潜在暴露情况受喷雾的粒径分布（PSD）影响。然而，目前的吸入风险评估并未将农药处理活动期间可能吸入的与人体相关的PSD考虑在内。本研究旨在表征用职业安全与健康管理局通用采样器（OVS）管收集的气溶胶的PSD，OVS管是工人暴露研究中常用于吸入风险评估的监测设备。使用牛津激光N60V粒径分析仪来表征各种农业喷嘴喷出的喷雾PSD。在喷洒稀释的百菌清制剂期间，同时使用OVS管和Respicon TM颗粒采样器进行空气采样，以表征收集在OVS管上的气溶胶的粒径分布。基于此比较，无论喷嘴喷雾质量如何，OVS管捕获了可吸入部分（质量中值直径（D50）= 100μm），总吸入浓度的约40%促成全身暴露（D50 = 10μm）。此外，与粗喷雾喷嘴相比，细喷雾和中喷雾喷嘴产生的空气传播浓度更高。因此，使用能喷出较大喷雾液滴的现代低漂移喷嘴（如空气诱导喷嘴）可大幅降低可吸入粒径部分内的空气传播浓度水平。虽然这些气道部分（如可吸入、胸腔、可吸入）内的浓度从极粗到极细喷雾喷嘴逐渐增加，但无论喷雾质量或喷嘴类型如何，每个部分在总可吸入浓度中的相对比例保持不变。此类关于农药应用PSD的信息可用于完善农业工人和旁观者的吸入风险评估。
