Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829 Landau, Germany.
Environ Sci Pollut Res Int. 2011 Jan;18(1):31-7. doi: 10.1007/s11356-010-0351-x. Epub 2010 Jun 11.
BACKGROUND, AIM AND SCOPE: Seed treatments are widely used on cereals and other annual crops throughout Europe. Most of the formulated pesticide is found on the outside of the seed, the husk. Risk assessments of seed treatments are especially needed for granivorous mice living in the agricultural landscape e.g. for registration using the guidance for risk assessment for birds and mammals (EFSA 2009). The dehusking of seeds before consumption is a known behaviour of these mammals, but so far, no quantitative data on the reduction of exposure of seed treatments by dehusking were published. Therefore, we aimed at providing a first quantitative estimate of this behaviour-related exposure reduction for the wood mouse (Apodemus sylvaticus) with different seed types.
We evaluated the efficiency of dehusking behaviour of 20 wood mice captured in the wild for four different seeds (wheat, barley, maize and sunflower). One experimental setup used a fungicide seed treatment where the remaining seed husks of consumed seeds were analysed with a HPLC-MS/MS technique. In the second setup, we measured generic pigment present in a blank seed treatment formulation and determined the leftover pigment in the husks with a photometric technique.
The exposure reduction was similar for the fungicide and the pigment design where the same seed types were studied. We could demonstrate exposure reductions ranging from around 60% for cereals to almost 100% for sunflower seeds as a result of the dehusking behaviour.
Since exposure reduction was similar in both approaches, working with pigments would be a generic way to estimate the impact of dehusking behaviour on seed treatment exposure. This behaviour can result in a substantial exposure reduction and should, therefore, be considered in a seed-type specific way in the risk assessment of pesticide seed treatments.
It is proposed to include a seed-specific dehusking factor in the calculations of estimated theoretical exposure of seed treatments for granivorous mice. The approach of accounting for a dehusking-related exposure reduction by field relevant wild mammal species seems a more promising way to advance the risk assessment instead of using generic species and neglecting behavioural traits. The pigment approach could be used to gather data for exposure reduction for other species and seed types. Its advantage is that it is harmless to the test species and comparatively cheap since no chemical analysis is involved.
Seed treatments are used for most of the cereal crops grown in Europe today. Their advantages usually include a lower application rate and the reduction of drift compared to a conventional spraying regime. However, there is a potential risk especially for granivorous mice, and its assessment is challenging in case of a high residue concentration on the dressed seeds. The concept of a dehusking factor in the risk assessment scheme for seed treatments for granivorous mice is a valid approach to account for the behavioural exposure reduction, and generic data could be easily generated also for other wild mammal species and other seed types, possibly analysing the pigment in commercial seed treatment formulations.
背景、目的和范围：种子处理在整个欧洲的谷类作物和其他一年生作物中广泛使用。大部分配制成的农药都存在于种子的外壳——种皮上。对于生活在农业景观中的食谷性老鼠，如为使用鸟类和哺乳动物风险评估指南（EFSA 2009）进行登记，特别需要对种子处理进行风险评估。这些哺乳动物在食用种子前会脱壳，这是已知的行为，但到目前为止，还没有发表关于脱壳行为降低种子处理暴露的定量数据。因此，我们旨在为不同类型的种子提供食谷性老鼠（林鼠）这种行为相关暴露减少的初步定量估计。
我们评估了 20 只从野外捕获的林鼠对四种不同种子（小麦、大麦、玉米和向日葵）的脱壳行为的效率。一个实验装置使用了一种杀菌剂种子处理，其中用 HPLC-MS/MS 技术分析消耗种子的剩余种皮。在第二个装置中，我们测量了空白种子处理配方中存在的通用色素，并使用分光光度法测定了种皮中的残留色素。
由于脱壳行为的原因，研究相同种子类型时，杀菌剂和色素设计的暴露减少情况相似。我们可以证明，由于脱壳行为，谷类种子的暴露减少约 60%，而向日葵种子的暴露减少几乎 100%。
由于两种方法的暴露减少情况相似，使用色素可能是一种通用方法，可以估计脱壳行为对种子处理暴露的影响。这种行为可能导致大量暴露减少，因此，在评估农药种子处理对食谷性老鼠的风险时，应根据种子类型进行具体考虑。
建议在估计食谷性老鼠对种子处理的理论暴露时，将种子特异性的脱壳因子纳入计算中。通过田间相关野生哺乳动物物种来评估与脱壳相关的暴露减少的方法似乎比使用通用物种并忽略行为特征更有前途。色素方法可用于收集其他物种和种子类型的暴露减少数据。其优点是对试验物种无害，且由于不涉及化学分析，因此相对便宜。
目前，欧洲种植的大多数谷类作物都使用种子处理。它们的优点通常包括与常规喷雾处理相比，施用量更低和漂移减少。然而，对于食谷性老鼠来说，存在潜在风险，而且如果处理后的种子上有高浓度的残留物，其风险评估具有挑战性。在食谷性老鼠的种子处理风险评估方案中，引入脱壳因子的概念是一种有效的方法，可以考虑行为暴露的减少，而且对于其他野生哺乳动物物种和其他种子类型，也可以很容易地生成通用数据，可能是通过分析商业种子处理配方中的色素来实现。
