Estimation/calculation of emissions of Plant Protection Products from protected crops greenhouses and cultivations grown under cover) to support the Development of risk assessment methodology under Council Directive 91/414/EEC and EU regulation 1107/2009 (EC)

Emissions of plant protection products (PPP) from covered crops to air, groundwater and surface water were estimated to support EFSA in the development of guidance on risk assessments for protected crops. Key driving factors for annual emissions to air from a multi-span greenhouse and walk-in tunnel in the southern zone were outside climate, vapour pressure and other factors influencing the volatilisation rate of the PPP, the ventilation rate of the greenhouse and competing loss processes of the PPP. A comparison between emissions via volatilisation in the field and emissions via ventilation from the covered structures was difficult, because it was not possible to use the same methodology to calculate both. Emissions to air via drift from an area covered with walk-in tunnels were estimated to be similar to those in the field. This is based on the assumptions that only a single tunnel on the leeward side of the area contributes to losses via drift and that different application techniques are used. Calculated emissions to groundwater of various PPP applied in a greenhouse in the central zone were smaller than emissions in the field. Annual emissions to surface water via drainage systems were also smaller for a soil-bound greenhouse crop than for a field crop except for rapidly degrading compounds. Losses of PPP to surface waters from soil-less systems depended on the application method and timing, the outdoor weather and characteristics of the growing system. The work indicated that wash-off of PPP with condensation water could potentially be an important process, but significant attenuation may occur before the PPP reaches surface water.

The model calculations showed that emissions from covered crops to all receptors are potentially significant. The results imply that a risk assessment should be undertaken for covered crops. In many cases, the risk assessment based on the methodology for the field is likely to be protective for covered crops, but there are situations where this may not be true. However, the uncertainties and limitations inherent in the assessment must be kept in mind and additional work is needed to test the validity of the conclusions drawn for a wider range of conditions. Emissions from soil-less cultivation systems via discharge and condensation and emissions from soil-bound systems via losses in condensation water are not addressed by the current risk assessment methodology for the field, because an equivalent route of entry does not exist outdoors. It may, thus, be necessary to develop risk assessment scenarios for these situations.