Open access publications in the SLU publication database

This report investigates the risks associated with unintentional spread of glypho-sate, through wind drift or leaching, from weed control on Swedish railways. The purpose of the work has been to determine how large non-spray zones that are normally required in order to protect sensitive areas close to railways. Risk charac-terization ratios were calculated for a number of scenarios by dividing predicted environmental concentrations (PEC-values) with predicted no-effect concentrations (PNEC-values). The calculations show that the risks posed to humans and surface waters are low and that this assessment is relatively insensitive to different assump-tions regarding how large the unintentional spread of glyphosate is. The minimum safety distances for protecting surface and drinking-waters (of 6 and 12 m, respec-tively) proposed by the Swedish Environmental Protection Agency are therefore sufficient. The risk of affecting the vegetation surrounding the railway is deemed acceptable but this assessment is more sensitive to the assumptions made. Since the wind drift measurements that have been made using the weed control train are not necessarily representative for how the train is used in Sweden, it is important that these measurements are repeated. The risk that private wells situated close to the railway are contaminated in concentrations exceeding 0.1 μg/l by glyphosate leach-ing from the railway cannot be ruled out and it is proposed that the need for non-spray zones close to such wells should be handled from case to case.