Exploring the Toxicity of Secondary Organic Aerosol formed from Atmospheric Oxidation of Pesticides

据估计，2015年全球农药（所有针对害虫的药剂，包括杀虫剂、除草剂、杀真菌剂和杀虫剂）的有效成分使用量为410万吨，预计到2025年将增加25%。农药主要在喷洒过程中进入大气，随后是气粒分离、表面挥发和风吹过程。它们在大气中的命运在很大程度上取决于它们的物理化学特性，例如它们对大气氧化剂的反应性、决定它们与颗粒分离的蒸汽压以及它们潜在的显著光解率。在过去十年中，许多实验室和实地研究表明，目前使用的农药与大气氧化剂（如羟基自由基，OH和臭氧，O3）的反应可以产生大量的二次有机气溶胶（SOA）质量。由农药氧化产生的SOA可以产生潜在的更持久和/或更有毒的产物，并且可以额外地促进对流层O3的产生。已经表明，在对水样中的某些农药进行紫外线处理的副产品的毒性增加是由于紫外线产生OH。同样，农药在大气中氧化形成的SOA也可能增加毒性负担。近年来，研究人员发现，生物源有机物的大气氧化过程中，由于与OH和O3的反应，会增加其毒性负荷，并且可以合理地预期，由农药氧化形成的SOA可能会影响人类和动物的健康。（曼彻斯特气溶胶室，MAC）、氧化流动反应器（OFR）化学和细胞生物学方法来探索SOA的形成和来自当前使用的农药的光氧化的毒性（即在OH和O3的存在下）。MAC和OFR可在大气相关环境条件下提供受控环境，可用于模拟农药的大气氧化。农药将通过喷洒的方式引入到MAC和OFR中，这一过程类似于作物中使用的过程。随后，将打开腔室的灯，启动光化学和氧化剂产生，导致SOA形成。MAC光源提供与真实的大气相似的光化通量光谱，但具有较低的强度，因此导致形成低SOA质量。OFR广泛的紫外线光源可以产生高浓度的氧化剂，产生高水平的SOA质量，这是随后的毒理学测定所必需的。国家的科学质谱技术将被用来基准的SOA组成从OFR产生的那些从MAC，以及监测所产生的SOA的物理和化学性质。这将进一步使研究小组能够探索它们的关键特性，提供有关其大气寿命和命运的信息。OFR SOA将通过撞击在模拟细胞外液（SEF）中取样，并将使用等分试样的样品来评估其心脏毒性，使用细胞系和完整心脏方法的组合来评估心脏功能和功能障碍标志物的关键方面。我们提出的一系列跨学科实验在我们独特的设施将探索我们的能力，以提供必要的信息，了解大气的命运，属性和毒性的SOA产生的当前使用的农药。这些信息对于向决策者、农药制造商和用户提供信息，以制定适当的准则和可持续产品至关重要。项目合作伙伴Ian Mudway的参与将通过他与NIHR健康保护研究单位的农药工作，通过UKHSA提供一条通往政府的途径。

Global usage of pesticides (all agents that target pests and including insecticides, herbicides, fungicides, and bactericides) was estimated at 4.1 million tonnes of active ingredient in 2015 and is expected to increase by 25% by 2025. Pesticides mainly enter the atmosphere during the spraying application followed by gas-to-particle partitioning, volatisation from surfaces and wind drifting processes. Their atmospheric fate is largely dependent on their physicochemical properties such as their reactivity towards atmospheric oxidants, their vapour pressure dictating their partitioning to particles as well as their potentially significant photolysis rates. Over the past decade, a number of laboratory and field studies have shown that the reaction of current-use pesticides with atmospheric oxidants (such as the hydroxyl radical, OH and ozone, O3) can yield to significant amounts of secondary organic aerosol (SOA) mass. The SOA produced from the oxidation of pesticides can yield products that are potentially more persistent and/or more toxic and can additionally contribute to tropospheric O3 production. Such an increase in the toxicity of the by-products of UV treatment of certain pesticides in water samples has been shown, effected by the UV generation of OH. Similarly, SOA formation from the atmospheric oxidation of pesticides may also increase the toxicity burden. The atmospheric oxidation of organic compounds from biogenic sources have recently found to increase to toxicity burden due to the reactions with OH and O3, and it is reasonable to expect that the SOA formed from the oxidation of the pesticides could affect human and animal health.We propose to combine cutting-edge, atmospheric simulation chamber (the Manchester Aerosol Chamber, MAC), oxidation flow reactor (OFR) chemistry and cell biology approaches to explore the SOA formation and toxicity from the photo-oxidation of current-use pesticides (i.e. in the presence of OH and O3). The MAC and OFR can provide a controlled environment under atmospherically-relevant environmental conditions that can be used to simulate the atmospheric oxidation of pesticides. Pesticides will be introduced into MAC and OFR by spraying, a process similar to that used in the crops. Subsequently, the lights of the chambers will be switched on, initiating the photochemistry and oxidant production, leading to SOA formation. MAC light sources provide similar actinic flux spectrum to that of the real atmosphere, yet with lower intensity thus resulting to low SOA mass formed. OFR's extensive UV light sources can generate high concentrations of oxidants, yielding high levels of SOA mass that is necessary for the subsequent toxicological assays. State-of-the-science mass spectrometry techniques will be used to benchmark the SOA composition generated from the OFR against those from the MAC, as well as to monitor the physical and chemical properties of the generated SOA. This will further enable the research team to explore their key-properties providing information about their atmospheric lifetimes and fate. The OFR SOA will be sampled in simulated extracellular fluid (SEF) by impingment and aliquots of the samples will be used to assess their cardiac toxicity using a combination of cell lines and intact hearts approaches to evaluate key aspects of cardiac function and markers of dysfunction. Our proposed series of interdisciplinary experiments in our unique facilities will explore our capability to provide information essential to understanding the atmospheric fate, properties and toxicity of SOA generated from the current-use pesticides. Such information is essential in informing policy makers, pesticide manufacturers and users in the development of adequate guidelines and sustainable products. Involvement of project partner Ian Mudway will provide a pathway through to Government via UKHSA through his work on pesticides with the NIHR Health Protection Research Unit.