The Directive 2009/128/CE of European Parliament and Council on Sustainable Use of Pesticides introduced a community action framework to protect the Environment of the EU and requested Member States to implement policies and actions in order to reduce the risk of pesticide use. In Italy, this Directive was adopted by D.Lgs. n.150 14/08/2012, followed by DGR n. X/3233 adopted on 06/03/2015 in the Lombardy Region: “Approvazione delle linee guida per l’applicazione in Lombardia del piano di azione nazionale (PAN) per l’uso sostenibile dei prodotti fitosanitari”. Both pesticides (CE 1107/2009) and biocides (UE 528/2012), once introduced into the environment, might lead to the formation of metabolites, degradation and reaction products. They could also move from the compartment they have been applied, and migrate in other non-target compartments. Due to their intrinsic toxic characteristics, these substances might cause negative acute or chronic effects to humans and to the environment. A well designed monitoring campaign of residues of pesticides in water may provide a clear picture of their distribution in the aquatic environment. The monitoring of pesticides is quite a complex activity, due to the number of chemicals involved, to their large application areas and to the different chemical characteristics of the substances. In Italy, every year, the ISPRA institute addresses and coordinates the Regional Environmental Protection Agencies – REPAs in the monitoring campaign activities of surface and ground water: providing prioritizing pesticide lists, sampling methodologies, and coordinating laboratory analysis and control. It has to be considered that the REPAs, Regional Environmental Protection Agencies’ surface water monitoring network is not specifically designed for pesticide residues, but for other purposes, mainly related to water quality (classification of the biological and chemical conditions of surface water). In addition, the sampling frequency is usually scheduled to occur at least twice a year, which does not correspond to the best practice to detect pesticide in surface water. Even if the monitoring punctual data of the residue level of a pesticide in surface water is merely a snap-shot of a situation that could over/under estimate an environmental pesticide pollution, in this context it is used as a Predicted (Measured) Environmental Concentration. Obviously, the monitored pesticide concentration in surface water is not a real PEC, and does not depend just on application methods, application doses and application period. Therefore, this assumption is to be considered as a first step of the environmental Concentration assessment of a pesticide in the surface water. The pesticide maximum concentrations were considered as the Monitored Environmental Concentration (MEC). A first screening of the potential pesticide risk for surface water was performed by comparing the MEC with the Environmental Quality Standard (annual average concentration) – EQS, Italian regulation limit for pesticides (DM 260/2010). To assess the pesticide risk to the aquatic ecosystem, the measured MEC of an active substance was compared with the corresponding Predicted No Effect Concentration for the aquatic ecosystem, i.e. the concentration of the substance which is expected not to produce any adverse effects to the aquatic ecosystem. A collection of ecotoxicological data have been retrieved for all the monitored pesticides; for each pesticide, the PNEC was derived from the most sensitive ecotoxicological value divided by a safety factor which account for the variability inter and intra specie. According to this criterium, taking into account also aquatic plants when herbicides were considered, the PNECaquatic were calculated for the selected pesticides.
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