Is copper fungicide that bad?

Downy mildew is one of the most important and severe diseases for greenhouse horticultural products. For disease control copper-based fungicides are the most effective and used active ingredients in both conventional and organic pest management. Copper (Cu) use is being limited and its reduction becomes one of the main principles of organic production. This study is focused on the characterization methods to assess copper compoundRSQUOs toxicity on agricultural systems in the frame of Life Cycle Assessment. USEtox model has been used to calculate Comparative Toxicity Potentials (CTPs) for freshwater ecotoxicity, linking emissions to impacts through fate, exposure and effects. The ecotoxicological impacts of 8 different fungicides for downy mildew control were estimated in two different geographic scales: global default values and Europe. The resulting CTPs showed up to 2 orders of magnitude of variation across all active ingredients in both geographic scales. Chlorothalonil had the highest and Cymoxanil had the lowest CTP in both scales. Comparing the two landscapes CTPs, the organic active ingredients had similar values, making spatial differentiation less influential. However, in the case of Azoxystrobin, Captan and Cu, European CTPs were higher at around one order of magnitude. Cu ranked third among the eight fungicides in default landscape, while in the European ranked sixth, making differentiation according to water archetypes potentially relevant. These results show that Cu toxicity depends mainly on its capacity to interact with the surrounding environment (pH, temperature, humidity, etc.), and the dynamics of this interaction (speciation). These results represent a better approximation to estimate copper toxicity, which may help the decision process on the use of copper fungicides, even though we recommend to deepen the assessment of the interactions with the emission site conditions. Therefore, a new model framework that takes into account the specific geographic distributions is needed.