Higher-tier assessment of the potential for groundwater issues due to the use of 1,3-D soil fumigant; evaluation of the active ingredient,metabolites

BACKGROUND: 1,3-Dichloropropene (1,3-D, CAS No. 542-75-6)is a broad-spectrum soil fumigant used to control numerousspecies of soilborne plant-parasitic nematodes. 1,3-D consists of two isomers, (Z)- and (E)-1,3-D. There are a number oflow-level chlorinated compounds that could potentially be produced as a part of the 1,3-D manufacturing process. 1,3-D andits metabolites, as well as potentially related chlorinated compounds, represent potential groundwater contaminants.RESULTS: This study has investigated the hydrolytic stability,under biotic and abiotic conditions in the laboratory, of anextensive representative list of 1,3-D and potentially related chlorinated compounds in order to predict their environmentalfate. All of these compounds showed intrinsic hydrolytic instability under both abiotic and biotic test conditions. Furthermore,a monitoring programme was carried out. Twenty-five wells were monitored in five Italian regions characterised by historicaland existing use of 1,3-D. The parent compound, its two major metabolites and potentially related chlorinated compoundswere not detected in the well water at>0.1μgL−1at any sampling location.CONCLUSION: The soil fumigant (E,Z)-1,3-D, its metabolites and potentially related chlorinated compounds constitute a lowrisk to groundwater.