In general, fungicides are moderately lipophilic (median log octanol–water partition coefficient ( K ow): 3.2 Figure 1A), a feature well-reflected by all major fungicide groups except for dithiocarbamates (median log K ow: 1.5 Figure 2A). Moreover, dithiocarbamates (aggregated with carbamates) and DMI fungicides account for approximately 29 and 24% of the mass of synthetic fungicides sold in the EU, whereas specific data on chloronitriles and strobilurins are lacking (subsumed under “other fungicides” accounting for more than 40% estimates for 11 member states reporting sales (3)). Geological Survey’s (USGS’s) preliminary data for 2016 (15)). (15) Dithiocarbamates, chloronitriles, demethylation inhibitors (DMIs), and strobilurins constitute major fungicide groups accounting for approximately 65, 12, 7, and 6% of the total synthetic fungicide mass used in the U.S. (14) In the United States (U.S.), which represents 80% of the total fungicide use in North America, (14) fungicides account for less than 10% (including inorganic fungicides) of the total mass of pesticides applied. (14) Geographically, Europe is considered the dominant market for fungicides with major applications on grains and cereals (e.g., wheat), fruits (with particularly intensive use in viticulture), and vegetables. In agricultural landscapes, fungicides are used predominantly on fruits and vegetables and contribute to more than 35% of the pesticide market share worldwide. For instance, only 13% of studies on pesticide effects between 19 focused on fungicides, compared to 62% and 24% for insecticides and herbicides, respectively. (9,10) Despite intensive use of fungicides and the associated potential ecotoxicological risks in nontarget aquatic systems, the environmental fate and effects of fungicides have received far less attention compared to insecticides and herbicides. In aquatic systems, fungicides can be toxic to a wide range of nontarget organisms as they act on basic biological processes that are not specific to fungi (e.g., energy production). (1,5,6) Following their use, fungicides can enter aquatic ecosystems via point (e.g., discharge from wastewater treatment plants following domestic and agricultural use (7)) and nonpoint (e.g., drift, drainage, surface runoff primarily from agricultural use (8)) sources.
(4) Moreover, fungicide use is regionally predicted to increase because of changes to climatic conditions, development of fungicide resistance, and invasive fungal species. (3) In wine-growing regions, fungicides can account for more than 90% of all pesticide applications.
(2) In the European Union (EU), fungicide sales (based on mass) account for more than 40% of the total pesticide sales with synthetic, organic fungicides accounting for approximately 60% of all fungicides. Finally, we outline central research gaps that currently challenge our ability to predict fungicide exposure and effects, promising research avenues, and shortcomings of the current environmental risk assessment for fungicides.Īs fungal diseases are a major threat to crop production, (1) the application of fungicides to control fungal infestations is often considered indispensable to secure global food supply. We additionally demonstrate that fungicides can be highly toxic to a broad range of organisms and can pose a risk to aquatic biota. We show that fungicides occur widely in aquatic systems, that the accuracy of predicted environmental concentrations is debatable, and that fungicide exposure can be effectively mitigated. We provide an overview of the risk of fungicides to aquatic ecosystems covering fungicide exposure (i.e., environmental fate, exposure modeling, and mitigation measures) as well as direct and indirect effects of fungicides on microorganisms, macrophytes, invertebrates, and vertebrates. However, in comparison to herbicides and insecticides, the exposure to and effects of fungicides have received less attention. Fungicides can reach aquatic ecosystems and occur in surface water bodies in agricultural catchments throughout the entire growing season due to their frequent, prophylactic application.
Fungicides are indispensable to global food security and their use is forecasted to intensify.
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