Ramaprasad Jaya, Tsai Min G-Yi, Fenske Richard A, Faustman Elaine M, Griffith William C, Felsot Allan S, Elgethun Kai, Weppner Sarah, Yost Michael G
Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington 98195-7234, USA.
J Expo Sci Environ Epidemiol. 2009 Sep;19(6):613-23. doi: 10.1038/jes.2008.66. Epub 2008 Oct 29.
We examined the significance of meteorology and postspray volatilization of methamidophos (an organophosphorus insecticide) in assessing potential inhalation risk to children in an agricultural community. We combined fluxes from sources and dispersion modeling with a range of possible local meteorology to create output to study the variability in potential community exposure as a result of changing temperature, wind speeds and wind directions. This work is based on an aerial spray drift study where air sampling measurements of methamidophos were made before, during and after a spray event were used to examine acute inhalation risk for children living in an Eastern Washington State community in close proximity (between 15 and 200 m) to sprayed potato fields. We compared the measured average air concentrations of methamidophos in the community to a "no observed adverse effect level" for subchronic inhalation to characterize acute and subchronic inhalation risks. The baseline estimates of inhalation exposure were below Environment Protection Agency's (EPA) level of concern based on a target margin of exposure of 300. As meteorological conditions during and after spraying influence the amount of material moving into areas where children reside we used historical meteorological data to drive model simulations that predicted likely air residue concentrations under different wind and temperature conditions. We also added variability to the decay constant and initial emission fluxes to create a 2-D simulation of estimated air concentrations in the community near the fields. This work provides a methodological framework for the assessment of air concentrations of pesticides from agricultural sprays in the absence of extended measurements, although including variability from meteorological conditions. The deterministic as well as the probabilistic risk analyses in this study indicated that postspray volatilization in the specific spray situation analyzed (methamidophos applied on potato fields in Eastern Washington) did not pose acute or subchronic risks as defined by the EPA. However, this study did not consider any pathway of exposure other than inhalation (e.g. diet, dermal, etc.) and the risk assessment should be evaluated in that context.
我们研究了气象条件以及甲胺磷（一种有机磷杀虫剂）喷雾后挥发情况在评估农业社区儿童潜在吸入风险方面的重要性。我们将来自源的通量和扩散模型与一系列可能的当地气象条件相结合，以生成输出结果，研究由于温度、风速和风向变化导致的潜在社区暴露的变异性。这项工作基于一项空中喷雾漂移研究，在一次喷雾事件之前、期间和之后对甲胺磷进行空气采样测量，以检查居住在华盛顿州东部社区、距离喷洒马铃薯田很近（15至200米之间）的儿童的急性吸入风险。我们将社区中甲胺磷的实测平均空气浓度与亚慢性吸入的“未观察到不良影响水平”进行比较，以表征急性和亚慢性吸入风险。基于300的目标暴露边际，吸入暴露的基线估计低于美国环境保护局（EPA）的关注水平。由于喷雾期间和之后的气象条件会影响进入儿童居住区域的物质数量，我们使用历史气象数据来驱动模型模拟，预测不同风和温度条件下可能的空气残留浓度。我们还对衰减常数和初始排放通量添加变异性，以创建田间附近社区估计空气浓度的二维模拟。这项工作提供了一个方法框架，用于在没有长期测量的情况下评估农业喷雾中农药的空气浓度，尽管考虑了气象条件的变异性。本研究中的确定性和概率性风险分析表明，在所分析的特定喷雾情况下（华盛顿州东部马铃薯田施用甲胺磷），喷雾后挥发并未造成EPA所定义的急性或亚慢性风险。然而，本研究未考虑除吸入之外的任何暴露途径（例如饮食、皮肤接触等），应在此背景下评估风险评估。
