EU Directive 91/414 requires member states to analyse the impact of plant protection products on the environment. Current methods of risk assessment are deterministic and do not take full account of uncertainties affecting risk. This leads to substantial difficulties in decision-making.

Probabilistic methods may help solve these problems, by quantifying uncertainty. The EU's Scientific Committee on Plants has recognised their potential, and they are already being implemented in North America. This workshop considered developing a harmonised European approach, and was organised with funding from the European Commission and with the support of the EU's Directorates General for Health and the Environment.

The workshop objectives were:

• Review the worldwide state of the art in probabilistic methods of risk assessment, for analysing the impact on the environment of plant protection products.



• Identify which aspects of the environmental evaluation of plant protection products under EU Directive 91/414 could be improved by using probabilistic methods.



• Define priorities for further research, data generation and other actions required to develop and implement these improvements