Despite laws and directives for the regulation and restriction of pesticides in farming, the large use of Plant-Protection Products (PPPs) in paddy fields is a relevant worldwide cause of environmental contamination. The aim of this work is to evaluate the environmental impact due to the use of PPPs by using an integrated approach based on chemical analyses and ecotoxicological hazard assessment, supported by statistical tools, in order to overcome the issues related to traditional tabular evaluation. Samples of soil and water of seven conventional and organic paddies located in Northern Italy were examined for two years. The results evidenced a direct relationship between the presence of Oxadiazon in water and bioassay responses as the main cause of the toxicity measured. This phenomenon affected both biological and conventional rice fields, due to the free circulation of water through irrigation canals. Therefore, the implementation of organic districts with water circulation isolated from conventional fields represents a simple and effective countermeasure to safeguard the agricultural practices of organic crops.

Despite laws and directives for the regulation and restriction of pesticide in farming, the large use of Plant Protection Products (PPPs) in paddy fields is a relevant worldwide cause of contamination of the environment. The aim of this work is to evaluate the environmental impact due to the use of PPPs by using an integrated approach based on chemical analyses and ecotoxicological hazard assessment, supported by statistical tools, in order to overcome the issues related to the traditional tabular evaluation. Samples of soil and water of seven conventional and organic paddies located in Northern Italy have been examined for two years by extensive chemical and ecotoxicological analyses. The results evidenced a direct relationship between the presence of Oxadiazon in water and bioassays responses as the main cause of the toxicity measured. This phenomenon affected both biological and conventional rice fields, due to the free circulation of water through irrigation canals. Therefore, the implementation of organic districts with a water circulation isolated from conventional fields represents a simple and effective countermeasure to safeguard the agricultural practices of organic crops.

The current environmental quality standards (EQSs) for freshwater ecosystems have been established in relation to the priority substances covered by Directive 2013/39/EU. The procedure for deriving EQSs that rely on the selection of the most sensitive toxicological data, with the application of arbitrary safety factors, is probably unrealistic for the Italian freshwater ecosystem. In this work, a procedure for the evaluation of specific sensitivity of 13 taxonomic groups from bacteria to amphibians and the derivation of protective chemical reference values specifically for the Italian aquatic communities was developed. Toxicological raw data of species belonging to the same taxonomic group spending at least one phase of their life cycle in Italian freshwater ecosystems were downloaded from EnviroTox and USEPA ECOTOX databases, aggregated, and then used as input for the model called Species Sensitivity Distribution in order to estimate the predicted no effect concentrations (PNECs). The comparison of relative sensitivity factors (RFSs) made it possible to identify the amphibians as the most sensitive group toward metals, trace elements, and pesticides, whereas crustacean were identified as the most sensitive group toward towards polycyclic aromatic hydrocarbons (PAHs). PNECs were estimated to cover 62 substances, of which 37 identified by Directive 2013/39/EU, and in most of the cases, the values were higher than EQSs. The PNECs reported in this work should be considered more realistic and tailored for Italian freshwater ecosystems, having significant repercussions in the classification of water bodies and the estimation of environmental impact assessment.