Understanding factors that affect dislodgeable foliar residues of pyrimethanil and their dissipation: How relevant is the crop-type for human exposure?

Pesticide dislodgeable foliar residues (DFR) and their dissipation half-time (DT₅₀) after application are important parameters for exposure and risk assessment from intended reentry activities or unintended dermal contact with treated crops. To understand the impact of agronomic factors on residue level a statistical based evaluation was conducted using ten DFR studies, with pyrimethanil applied in Scala^® to strawberries, raspberries, peppers, apples, and grapes, 30 trials in total. Influences on initial DFR (DFR0) and DT₅₀ were investigated by multivariate linear regression analysis. The application rate and the crop itself indicate a potential influence on DFR0 when related to ground area applied which is not notable for three dimensional crops regardless of indoor/outdoor cultivation, when related to leaf wall area (LWA). DFR0 values for pyrimethanil do not depend on the number of applications as the range of DT₅₀ values determined for pyrimethanil is consistently small (0.3–2.3 days). All DT₅₀ are significantly lower than the European default (30 days). The noted difference in DT50 of peppers to strawberries is likely attributable to indoor cultivation. A proposal is made how to refine the exposure assessment of pyrimethanil making use of the available DFR0 and DT₅₀ data for other crop types.

农药可洗脱叶片残留量（dislodgeable foliar residues, DFR）及其施药后的消解半衰期（dissipation half-time, DT₅₀），是开展有意再接触或无意经皮接触施药作物的暴露评估与风险评估的关键参数。为明确农艺因素对残留水平的影响，本研究基于10项DFR研究开展了基于统计学的评估：以嘧霉胺（pyrimethanil）通过Scala®制剂分别施用于草莓、树莓、辣椒、苹果与葡萄，共计30组试验。通过多元线性回归分析，探究了初始可洗脱叶片残留量（DFR₀）与DT₅₀的影响因素。结果表明，当以施药地块面积为基准时，施药剂量与作物种类对DFR₀存在潜在影响；但对于三维作物而言，无论采用室内还是室外种植模式，以叶墙面积（leaf wall area, LWA）为基准时，上述影响均不显著。嘧霉胺的DFR₀值不受施药次数影响，且其对应的DT₅₀值区间始终较小（0.3~2.3天）。所有试验得到的DT₅₀均显著低于欧盟默认值（30天）。辣椒与草莓的DT₅₀存在显著差异，这可能与辣椒采用室内种植有关。基于现有针对其他作物类型的DFR₀与DT₅₀数据，本研究提出了优化嘧霉胺暴露评估的可行方案。