Optimizing exposure data collection for plant protection products: identifying ideal collectors with the fluorescent dye pyranine

Abstract

When approving plant protection products, exposure data are required for risk analysis. Exposure data can be collected for various exposure pathways, such as dermal, inhalation or ground sediment. For measuring exposures, pyranine, a fluorescent dye, and a collector can be used. However, the choice of collector material depends on the specific exposure pathway. This study aims to determine the most suitable collector, in combination with the tracer pyranine, for recording exposure through different pathways in practical trials.Seven different collectors (Tyvek®, labels, plastic patches, paper patches, nylon filters, fibreglass filters, petri dishes) were subjected to laboratory and field tests to assess various quality parameters. Blank values, recovery rates, storability, and fluorescence degradation under UV-radiation were measured. Based on the results, a matrix was created summarizing which collector might be best suited to capture each exposure pathway. Almost all collectors demonstrated high recovery rates (Tyvek® 100%; labels 100%; plastic patches 100%; paper patches 100%; nylon filters 95%; fiberglass filters 60.9%) as well as good storability. Furthermore, all plastic-based collectors (labels, Tyvek®, plastic patches, petri dishes) showed a very good recovery rate above 95% when exposed to UV-radiation. However, nylon filters were not suitable for utilization under field conditions due to the rapid degradation of fluorescence under UV-radiation (recovery rate: 20–56%). Nevertheless, nylon filters showed stable recoveries under protected conditions and can be used to assess inhalation exposures under these conditions. Fibreglass filters, with recovery rates of 84–86%, were well-suited for testing inhalative exposures outdoors when a correction factor was applied. Tyvek® was the most suitable material for detecting total dermal exposure under field conditions. This is due to its quality characteristics and availability in a variety of sizes. Finally, petri dishes were ideal for collecting ground sediments.