To ensure compliance with food safety regulations, monitoring programs and reliable analytical methods to detect relevant chemical pollutants in food and the environment are key instruments. Pesticides are an important part of pest management in agriculture to sustain and increase crop yields and control post-harvest decay, while pesticide residues in food may pose a risk to human health. Thus, the levels of pesticide residues in food must be controlled and should align with Maximum Residue Levels regulations to ensure food safety. Food safety monitoring programs and analytical methods for pesticide residues and metabolites are well developed. Future developments to ensure food safety must include the increased awareness and improved regulatory framework to meet the challenges with natural toxins, emerging contaminants, novel biopesticides, and antimicrobial resistance in food and the environment. The reality of a complex mixture of pollutants, natural toxins, and their metabolites potentially occurring in food and the environment implies the necessity to consider combined effects of chemicals in risk assessment. Here, we present challenges, monitoring efforts, and future perspectives for chemical food safety focused on the importance of current developments in high-resolution mass spectrometry (HRMS) technologies to meet the needs in food safety and environmental monitoring.

Weather patterns of Northern Europe are projected to change with increased temperature and precipitation by 2050. These climatic changes can potentially affect the transport and degradation of pesticides in the environment. Moreover, pesticide application patterns are expected to be altered as plant disease and insect pests potentially increase. Other agricultural practices are also expected to change such as crop types and application rate. We have used a Bayesian network model to better integrate these potential direct and indirect climate change effects on pesticide exposure, in a probabilistic approach to pesticide risk assessment. The Bayesian network serves as a meta-model to incorporate the predictions from a pesticide fate and transport model (i.e. WISPE). In this study, we ran the exposure prediction model for specific environmental factors linked to a representative Norwegian study area such as soil and site parameters together with chemical properties, under different scenarios of climate model projections and pesticide application patterns. The Bayesian network links the pesticide exposure predictions derived for this study area to effect distributions derived from toxicity tests to predict the probability distribution of the risk quotient to surrounding aquatic ecosystemsThus, this approach takes into account both direct climate change impacts (on pesticides fate and transport) and indirect effects (on pesticide application). Compared to traditional (deterministic) risk assessment methods, this probabilistic approach can better account for uncertainty associated with climate projections,

The use of Bayesian networks (BN) for environmental risk assessment has increased in recent years as they offer a more transparent way to characterize risk and evaluate uncertainty than the traditional risk assessment paradigms. In this study, a novel probabilistic approach applying a BN for risk calculation was further developed and explored by linking the calculation a risk quotient to alternative future scenarios. This extended version of the BN model uses predictions from a process-based pesticide exposure model (World Integrated System for Pesticide Exposure - WISPE) in the exposure characterization and toxicity test data in the effect characterization. The probability distributions for exposure and effect are combined into a risk characterization (i.e. the probability distribution of a risk quotient), a common measure of the exceedance of an environmentally safe exposure threshold. The BN model was used to account for variabilities of the predicted pesticide exposure in agricultural streams, and inter-species variability in sensitivity to the pesticide among freshwater species. In Northern Europe, future climate scenarios typically predict increased temperature and precipitation, which can be expected to cause an increase in weed infestations, plant disease and insect pests. Such climate-related changes in pest pressure in turn can give rise to altered agricultural practices, such as increased pesticide application rates, as an adaptation to climate change. The WISPE model was used to link a set of scenarios consisting of two climate models, three pesticide application scenarios and three periods (year ranges), for a case study in South-East Norway. The model was set up for the case study by specifying environmental factors such as soil properties and field slope together with chemical properties of pesticides to predict the pesticide exposure in streams adjacent to the agricultural fields. The model was parameterized and evaluated for five selected pesticides: the three herbicides clopyralid, fluroxypyr-meptyl, and 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), and the two fungicides prothiocanzole and trifloxystrobin. This approach enabled the calculation and visualization of probability distribution of the risk quotients for the future time horizons 2050 and 2085. The risk posed by the pesticides were in general low for this case study, with highest probability of the risk quotient exceeding 1 for the two herbicides fluroxypyr-meptyl and MCPA. The future climate projections used here resulted in only minor changes in predicted exposure concentrations and thereby future risk. However, a stronger increase in risk was predicted for the scenarios with increased pesticide application, which can represent an adaptation to a future climate with higher pest pressures. In the current study, the specific BN model predictions were constrained by an existing set of climate projections which represented only one IPCC scenario (A1B) and two climate models. Further advancement of the BN modelling demonstrated herein, including more recent climate scenarios and a larger set of climate models, is anticipated to result in more relevant risk characterization also for future climate conditions. This probabilistic approach will have the potential to aid targeted management of ecological risks in support of future research, industry and regulatory needs.

Difenoconazole is a widely used triazole fungicide that has been frequently detected in the environment, but comprehensive study about its environmental fate and toxicity of potential transformation products (TPs) is still lacking. Here, laboratory experiments were conducted to investigate the degradation kinetics, pathways, and toxicity of transformation products of difenoconazole. 12, 4 and 4 TPs generated by photolysis, hydrolysis and soil degradation were identified via UHPLC-QTOF/MS and the UNIFI software. Four intermediates TP295, TP295A, TP354A and TP387A reported for the first time were confirmed by purchase or synthesis of their standards, and they were further quantified using UHPLC-MS/MS in all tested samples. The main transformation reactions observed for difenoconazole were oxidation, dechlorination and hydroxylation in the environment. ECOSAR prediction and laboratory tests showed that the acute toxicities of four novel TPs on Brachydanio rerio, Daphnia magna and Selenastrum capricornutum are substantially lower than that of difenoconazole, while all the TPs except for TP277C were predicted chronically very toxic to fish, which may pose a potential threat to aquatic ecosystems. The results are important for elucidating the environmental fate of difenoconazole and assessing the environmental risks, and further provide guidance for scientific and reasonable use.

Core Ideas Macropore flow may be enhanced in partly frozen soil. We developed a dual‐permeability modeling approach for frozen soils. Four test cases of increasing complexity were evaluated. Modeling results are in agreement with current process understanding. Measured data are lacking for a more quantitative evaluation of the model. Preferential flow may become significant in partially frozen soils because infiltration can occur through large, initially air‐filled pores surrounded by a soil matrix with limited infiltration capacity. The objectives of this study were to develop and evaluate a dual‐permeability approach for simulating water flow and heat transport in macroporous soils undergoing freezing and thawing. This was achieved by introducing physically based equations for soil freezing and thawing into the dual‐permeability model MACRO. Richards' equation and the heat flow equation were loosely coupled using the generalized Clapeyron equation for the soil micropore domain. Freezing and thawing of macropore water is governed by a first‐order equation for energy transfer between the micropore and macropore domains. We assumed that macropore water was unaffected by capillary forces, so that water in macropores freezes at 0°C. The performance of the model was evaluated for four test cases: (i) redistribution of water in the micropore domain during freezing, (ii) a comparison between the first‐order energy transfer approach and the heat conduction equation, (iii) infiltration and water flow in frozen soil with an initially air‐filled macropore domain, and (iv) thawing from the soil surface during constant‐rate rainfall. Results show that the model behaves in accordance with the current understanding of water flow and heat transport in frozen macroporous soil. To improve modeling of water and heat flow in frozen soils, attention should now be focused on providing experimental data suitable for evaluating models that account for macropore flow.

Core Ideas Significantly more pesticides leached from frozen than from unfrozen soil columns. Rapid breakthrough of pesticides indicated preferential flow in frozen soil. A strong negative correlation between Kf and leaching was observed. The effect of sorption properties is weaker in the presence of macropore flow. Macropore flow may be less important for highly mobile or highly sorbed pesticides. Field and laboratory studies show increased leaching of pesticides through macropores in frozen soil. Fast macropore flow has been shown to reduce the influence of pesticide properties on leaching, but data on these processes are scarce. The objective of this study was to investigate the effect of soil freezing and thawing on transport of pesticides with a range of soil sorption coefficients (Kf). To do this we conducted a soil column study to quantify the transport of bromide and five pesticides (2‐methyl‐4‐chlorophenoxyacetic acid, clomazone, boscalid, propiconazole, and diflufenican). Intact topsoil and subsoil columns from two agricultural soils (silt and loam) in southeastern Norway were used in this experiment, and pesticides were applied to the soil surface in all columns. Half the columns were then frozen (−3°C), and the other half were left unfrozen (4°C). Columns were subjected to repeated irrigation events where 25 mm of rainwater was applied during 5 h at each event. Irrigations were followed by 14‐d periods of freezing or refrigeration. Percolate was collected and analyzed for pesticides and bromide. Pesticide leaching was up to five orders of magnitude larger from frozen than unfrozen columns. Early breakthrough (<<1 pore volume) of high concentrations was observed for pesticides in frozen columns, indicating that leaching was dominated by preferential flow. The rank order in pesticide leaching observed in this study corresponded to the rank order of mean Kf values for the pesticides, and the results suggest that sorption plays a role in determining leaching losses even in frozen soil.

Limited knowledge and experimental data exist on pesticide leaching through partially frozen soil. The objective of this study was to better understand the complex processes of freezing and thawing and the effects these processes have on water flow and pesticide transport through soil. To achieve this we conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer and the herbicide MCPA in partially frozen soil. In total 40 intact topsoil and subsoil columns from two agricultural fields with contrasting soil types (silt and loam) in South-East Norway were used in this experiment. MCPA and bromide were applied on top of all columns. Half the columns were then frozen at -3 degrees C while the other half of the columns were stored at +4 degrees C. Columns were then subjected to repeated irrigation events at a rate of 5 mm artificial rainwater for 5 h at each event. Each irrigation was followed by 14-day periods of freezing or refrigeration. Percolate was collected and analysed for MCPA and bromide. The results show that nearly 100% more MCPA leached from frozen than unfrozen topsoil columns of Hov silt and Kroer loam soils. Leaching patterns of bromide and MCPA were very similar in frozen columns with high concentrations and clear peaks early in the irrigation process, and with lower concentrations leaching at later stages. Hardly any MCPA leached from unfrozen topsoil columns (0.4-0.5% of applied amount) and concentrations were very low. Bromide showed a different flow pattern indicating a more uniform advective-dispersive transport process in the unfrozen columns with higher concentrations leaching but without clear concentration peaks. This study documents that pesticides can be preferentially transported through soil macropores at relatively high concentrations in partially frozen soil. These findings indicate, that monitoring programs should include sampling during snow melt or early spring in areas were soil frost is common as this period could imply exposure peaks in groundwater or surface water.

The recent revision of the legal framework for authorization of use of plant protection products and pesticides within the European Union/European Economic Area (EU/EEA; Regulation EC 1107/2009, Directive 2009/128/EC) imposes a need for close collaboration across country borders within the three pesticide authorization zones (designated the north, central, and south zones) in Europe. The principles of zonal evaluation and mutual recognition embedded in Regulation EC 1107/2009 concerning marketing of plant protection products are intended to reduce the approval times for pesticides. However, the three authorization zones represent a very simplified view compared to the 16 climatic zones/scenarios that have been outlined for pesticide modeling in Europe (Blenkinsop et al. 2008; Fig. 1). Pedoclimatic or agricultural constraints could entitle the individual states to adopt restrictions on the use of pesticides approved within their zone or even to refuse approval. Fig. 1 Zones for pesticide authorization overlaid on climatic zones for pesticide modeling (reprinted from Blenkinsop et al. 2008 with permission from Elsevier) in Europe To achieve a sound scientific basis for zonal evaluation and collaboration on a regulatory level, it is also necessary to increase research collaboration and knowledge exchange within the scientific community. Here, we report the main conclusions and recommendations from a Nordic-Baltic workshop on the environmental fate of pesticides, which was conducted in As, Norway, in September 2014 with the aim of promoting knowledge exchange, network building, and a common agenda for future research within the northern zone. Pesticide regulatory risk assessment in the northern zone Zonal evaluation and mutual recognition The “Guidance document on work sharing in the Northern zone in the authorization of plant protection products” (Anonymous 2015) states that the northern zone cooperation includes the EU member states Denmark, Sweden, Finland, Estonia, Latvia, and Lithuania, as well as the European Economic Community/European Free Trade Association (EEC/EFTA) members Norway and Iceland. The guidance document was implemented in all countries within the zone from January 2015. Climatic zones for pesticide modeling (Blenkinsop et al. 2008) reflect the complexity of the different authorization zones within Europe (Fig. 1). According to this classification, the northern zone countries cover seven of the 16 climatic zones (Table ​(Table1).1). The variation within the northern zone is further illustrated by the 13 environmental zones representing an aggregation of the environmental stratification of Europe (Metzger et al. 2005; Jongman et al. 2006), five of which are covered by the northern zone countries (Table ​(Table2).2). The duration of the growing season and the sum of active temperatures are doubled when moving southward from the alpine north to the Atlantic north. This will inevitably affect the possibility of harmonizing risk assessment procedures and/or requirements between the countries within the northern zone, and it will also influence the commercial viability of the pesticide industry. Table 1 Climate zones for pesticide modeling (Blenkinsop et al. 2008) in the northern zone countries Table 2 Growing season characteristics in the northern zone based on the environmental stratification of Europe (Metzger et al. 2005; Jongman et al. 2006) Due to the strict limits of the timeline for the zonal evaluation (SANCO/13169/2010 rev. 9), there must be good agreement between the countries in the northern zone to ensure a satisfactory risk assessment. The time frame during which the member states are to appraise specific national concerns comprises a period of 6 weeks for commenting on the draft regulatory report and 120 days for assessment after the initial zonal evaluation.

Changes in climatic conditions affect concentrations and total losses of pesticides in runoff from agricultural fields. Measurements on runoff of pesticides with different mobility characteristics have been performed at three agricultural fields in SENorway. Volume proportional samples of both surface and drainage runoff have been collected at an annual bases for three years (2001-02, 2002-03 and 2005-06). At an annual scale, accumulated losses of pesticides in drainage runoff might be significant, especially for mobile pesticides. Predictions of environmental concentrations of pesticides have been performed from one of the fields, based on simulations with the MACRO model. Here, the drainage runoff of the mobile pesticide metalaxyl has been simulated for three different years with different climatic conditions. Generally, simulated values agreed well with measured values for annual losses of the pesticide, where climatic events of importance for the runoff of the pesticide were well accounted for. INTRODUCTION Regardless of water solubility or affinity for solid surfaces, pesticides that are applied at agricultural fields are frequently found in brooks and rivers (e.g. Ludvigsen and Lode, 2005). Concentrations and total losses of pesticides are, however, heavily dependent on climatic conditions. Especially, precipitation events shortly after application and melting-freezing episodes during winter are of great concern with respect to runoff of pesticides (Riise et al., 2006). The transport of pesticides occurs both through surface and drainage runoff, depending on soil and climate conditions. Concerning annual fluxes of pesticides, a significant part might pass through the drainage water (Riise et al., 2004). At three agricultural fields in SE-Norway, primary data on runoff of pesticides with different mobility characteristics (bentazone, metalaxyl, propiconazole) have been collected, at a plot scale, for several years. Volume proportional samples have been taken from both surface and drainage runoff at the edge of the fields, to calculate annual fluxes. In addition, the pesticide losses to drainage from one of the sites have been simulated with MACRO, a dual permeability model (Jarvis, 1991). The aim of the study has been to improve the knowledge on factors contributing to the loss of pesticides from fields with different soil characteristics under different climatic conditions. MATERIAL AND METHODS Field experiments: Pesticides were applied in the beginning of June at three agricultural plots in SE-Norway (Askim, Bjørnebekk and Askim) the following years: 2001, 2002 and 2005. KBr was applied at the same time as the pesticides. Runoff measurements were performed from 1. June – 31. May. Two of the sites Bjørnebekk and Syverud – are located at Ås and one site at Askim, 30 km east of Ås. The soils at all sites have a clay content greater than 20 %; and are characterized as loam/silt loam to silty clay loams (Tab. 1). Two sites, Bjørnebekk and Askim, are artificially levelled. Surface runoff was measured at all sites, while drainage runoff was measured at Syverud and Askim only. Surface runoff was collected by a plastic half pipe at the end of the plots. Volume proportional samples were taken by using tilting buckets which added a small volume of water to a collecting can every second tilt. A further description of the experimental sites and setup can be found in Lundekvam (2007). In general, all plots were subject to either harrowing or ploughing both during spring and autumn. For the season 2005/2006 one plot with no tillage during autumn was also included (Fig. 3). The plots were fertilized and sown (spring barley) in spring. Climate: Precipitation, air temperature and snow depth were measured at the agrometeorological field station (http://www.umb.no/imt/fagklim/metdata) at Ås, and soil frost depth is estimated from measurements with soil moisture resistance blocks at the Soil Water Monitoring Station at Ås (Hervé Colleuille, NVE pers.comm.). Table 1. Soil properties of the agricultural plots at Askim, Bjørnebekk and Syverud Askim Bjørnebekk Syverud Soil type Silty clay loam Silty clay loam Loam/silt loam Plot area (m) 324 178 402