The Danish Pesticide Leaching Assessment Programme. Monitoring results May 1999 - June 2023

In 1998, the Danish Parliament initiated the Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme aimed at evaluating the leaching risk of pesticides and/or their degradation products under field conditions. The objective of PLAP is to improve the scientific foundation for decision-making in the Danish regulation of pesticides by enabling field studies to be included in the risk assessment of selected pesticides. The specific aim is to evaluate whether approved pesticides applied in accordance with current regulations and maximum permitted dosages according to crop and BBCH stages, under actual, Danish field conditions can result in leaching of the pesticides and/or their degradation products to the groundwater in concentrations exceeding the limit value of 0.1 µg/L for groundwater and drinking water.

This report focuses on results from the period July 2021 – June 2023. During this period, 17 different products containing a total of 14 different active ingredients were applied to the PLAP fields as part of the agricultural management. Only selected active ingredients from these products were chosen for testing, and therefore some of the active ingredients applied are not included in the monitoring or evaluated in this report.

The current report presents the results of tests carried out on four different agriculture fields, of which one is sandy (Jyndevad) and the other three consist mainly of clay till (Silstrup, Estrup, Faardrup). It is noted that several active ingredients were applied to the fields before July 1, 2021, for which either the active ingredient, degradation product/s, or both were included in the monitoring. In the evaluation of the individual test of specific compounds, we have therefore included the results of chemical analyses carried out before July 2021 in cases where this was needed. A summary of the results is given in Table 0.1 for all samples included in the monitoring and evaluations in the present reporting period (July 2021 to June 2023). The report represents either preliminary or final results of the testing of 16 active ingredients (for simplicity hereafter referred to as pesticides), of which two pesticides and a total of 17 degradation products were included in the monitoring. The pesticides were applied to the PLAP fields by spraying 14 different commercial products. In some cases, the commercial products contained one or more pesticides, and in other cases, the same pesticide was applied to the fields using different commercial products.

Please refer to Table 7.1 and Table 7.2 for a historical perspective of the entire monitoring in PLAP from 19992023, which has so far included tests of 70 pesticides (active ingredients), from which analyses of either the pesticide itself or one or more of its degradation products have been included in the monitoring. In total, 53 pesticides and 105 degradation products (158 in total) have been included in the monitoring. Detailed information and results of previous tests can be found in previous PLAP reports (e.g. Badawi et al. 2023b and other reports available at www.plap.dk).

Starting from October 1, 2022, all pesticide monitoring at Lund was put on standby due to uncertainty of the hydraulic connectivity in the monitoring wells and the percolating water from the field. Pesticide tests that were active at Lund at that time, will not undergo evaluation and previous evaluated tests should not be used in pesticide assessments, as the uncertainty in hydraulic connectivity can affect the outcome of the tests (the lack of detections can be a consequence of lacking hydraulic connectivity). The bromide tracer experiment, initially done in 2017 when the field was established, appears to have been erroneous. Consequently, a new bromide tracer experiment was initiated in January 2023 and will be assessed in the upcoming years.