The EYP has been developed as a tool for farmers to select pesticides with the least environmental impact and to quantify the impact of their use. For each pesticide the yardstick assigns environmental impact points for the risk to water organisms, the risk of groundwater contamination and the risk to soil.
There are three output values: acute risk to water organisms (most sensitive organism); risk of groundwater contamination; acute and chronic risk to soil organisms. The potential risk is expressed in environmental impact points (EIPs). The more EIPs a pesticide gets, the higher its impact on the environment. The EIPs are based on the predicted environmental concentration (PEC) in a certain compartment and the maximum permissible concentration (MPC) set by the Dutch government. The EIP are initially assigned for a standard application of 1 kg active ingredient per hectare. For different rates of application, the number of EIP is multiplied by the actual dose.
The score on the yardstick depends on chemical properties (persistence and mobility in soil, toxicity) of both active ingredient and principal metabolites, dose rate, organic matter content of the soil (infuences transportation in soil), time of application (infuences degradation and transportation in soil), method of application (infuences the amount of emission to surface water) and distance to surface water (infuences the amount of emission to surface water).
The data on degradation rates, adsorption coeffcients, toxicity to aquatic organisms and toxicity to soil organisms are drawn from data sheets compiled by the Dutch Regulatory Committee for agrochemicals.
As the name indicates the EYP only considers environmental effects of pesticides. EYP is not as widely used, as for example EIQ, but has been applied to assess the impact of pesticide use in integrated and conventional potato production in the Netherlands (De Jong and De Snoo, 2002). EYP calculates PEC values but rather than comparing these values to LC/LD/EC/ED50 and NOEC values they are multiplied by pesticide toxicity data to produce Environmental Impact Points (Reus and Leendertse, 2000).