The pesticides regulatory authority in the Netherlands, the Ctgb, has further updated the leaching chapter of its fate and behaviour manual for national assessments (version 2.3).
Changes include information on conducting multiple runs with GEOPEARL in cases where a relationship between active substance behaviour such as adsorption/desorption and soil properties (e.g. pH or organic matter) is noted.
GeoPEARL has a function to include a boundary of soil properties in the plot selection. For example, one run is conducted using plots for acidic conditions and a second for alkaline conditions. This boundary must be defined by the user.
GeoPEARL will then produce results for two sets of 250 plots, one for acidic soil and one for alkaline soil. The user must combine these results to calculate an overall 90 th percentile spatial concentration for use in the exposure assessment. NB: Standard PECGW calculations use an 80th percentile value.
For advice on risk assessment requirements for the Netherlands and further information on the registration of plant protection products, biocides or general chemicals, or any other regulatory issues, please contact ERM on +44 (0)1423 520245,enquiries-harrogate@erm.com.