Background: 1,3 Dichloropropene (1,3-D) is a preplanting soil fumigant for the control of cyst and free-living nematodes and is currently undergoing a resubmission under Annex 1 listing of Directive 91/414/EEC. The characteristics of 1,3-D are such that the risk of it or its soil metabolites leaching through the soil profile cannot be excluded. As such, groundwater monitoring programmes were established in five EU countries representing a wide range of agricultural, climatic and hydrogeological situations, covering a range of groundwater vulnerability scenarios. All monitoring was conducted in areas where there has been historical use of 1,3-D.
Results: Over 5000 groundwater samples were analysed for the presence of 1,3-D and its metabolites over a 2 year period. Almost all analyses (for parent and metabolites) yielded concentrations of <0.1 microg L(-1). There were just two detections of >0.1 microg L(-1) (0.12 microg L(-1) and 0.4 microg L(-1)) for the 3-chloroacrylic acid metabolite in shallow groundwater samples of the alluvial gravels of the River Tiétar in the Caceres region of Spain.
Conclusion: Groundwater monitoring programmes have been conducted in the EU in five countries. These have demonstrated that there is negligible contamination of groundwater with 1,3-D or its metabolites across a range of agroclimatic regions where 1,3-D is known to have been used for a number of years. Local scientific knowledge of geological features, hydrology, agricultural practice and specific local issues was essential to the conduct of the study.