Pesticide Mass Research Articles

Particle size distributions of current-use pesticides in three European atmospheric environments

As an implication of their semivolatility, aerosols play a key role in the environmental transport and fate of current-use pesticides (CUPs). Size-segregated PM10 samples were collected at each one rural, urban residential and coastal site during a pesticide application season. Out of 72 targeted CUPs, the mass size distribution of 48 CUPs was determined. Individual pesticide mass median diameters were found in the submicrometer as well as in the supermicrometer range. The findings suggest that the PM10 mass size distribution and chemical composition influenced the CUPs mass size distributions.

Effects of soil redistribution by tillage on subsequent transport of pesticide to subsurface drains.

Tillage operations will change the distribution in soil for any pesticide residues still present from earlier applications. This redistributive effect of tillage has been neglected in the study of pesticide leaching behavior. This study reviews the literature to characterize this redistributive effect for different tillage operations and uses a pesticide leaching model to investigate the impact of redistribution on pesticide transport to subsurface drains which is a significant input route to surface water bodies. Inversion ploughing moves the majority of any residues of pesticide present at or near the soil surface into the bottom two-thirds of the plough layer, whereas non-inversion ploughing has only a limited redistributive effect. Incorporating this redistributive effect into model simulations resulted in large changes (typically 5-10-fold difference) in both the maximum concentration and total mass of pesticide transported to drains over the winter following cultivation. More intense cultivation decreased subsequent leaching for relatively mobile compounds (Koc ≤1000 mL g-1 ), but increased it for strongly sorbed pesticides (Koc ≥2000 mL g-1 ). The redistributive effect of soil tillage on pesticide residues can have a large effect on subsequent transport to subsurface drains. This effect has been neglected in the literature. Field research is required to validate the model simulations presented here, and consideration should be given as to whether the effect needs to be included within risk assessment procedures. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Investigation of Relationships Between the Geospatial Distribution of Cancer Incidence and Estimated Pesticide Use in the U.S. West.

The objective of the study was to evaluate the potential geospatial relationship between agricultural pesticide use and two cancer metrics (pediatric cancer incidence and total cancer incidence) across each of the 11 contiguous states in the Western United States at state and county resolution. The pesticide usage data were collected from the U.S. Geological Survey Pesticide National Synthesis Project database, while cancer data for each state were compiled from the National Cancer Institute State Cancer Profiles. At the state spatial scale, this study identified a significant positive association between the total mass of fumigants and pediatric cancer incidence, and also between the mass of one fumigant in particular, metam, and total cancer incidence (P‐value < 0.05). At the county scale, the relationship of all cancer incidence to pesticide usage was evaluated using a multilevel model including pesticide mass and pesticide mass tertiles. Low pediatric cancer rates in many counties precluded this type of evaluation in association with pesticide usage. At the county scale, the multilevel model using fumigant mass, fumigant mass tertiles, county, and state predicted the total cancer incidence (R‐squared = 0.95, NSE = 0.91, and Sum of square of residuals [SSR] = 8.22). Moreover, this study identified significant associations between total fumigant mass, high and medium tertiles of fumigant mass, total pesticide mass, and high tertiles of pesticide mass relative to total cancer incidence across counties. Fumigant application rate was shown to be important relative to the incidence of total cancer and pediatric cancer, at both state and county scales.

Removal of Urban-Use Insecticides in a Large Open-Water Wetland Pond

Worsening freshwater scarcity has heightened the need for treatment technologies capable of eliminating chemical and biological contaminants to allow for the beneficial use of traditionally underutilized water resources. In urbanized arid and semiarid regions such as California, urban drainage represents an increasingly important water source for augmenting water supply. However, monitoring shows that urban streams are contaminated ubiquitously with urban-use insecticides (e.g., pyrethroids and fipronil) that have broad-spectrum toxicity. In this study, a large open-water wetland pond (OWWP), characterized by shallow water depth and the absence of permanent vegetation, was evaluated for the removal of pyrethroids and fipronil (and its biologically active degradates). Concentration-based removal and changes in the pesticide mass flux were calculated to determine the efficacy of the OWWP. Toxic units for indicator aquatic invertebrates were estimated before and after the OWWP treatment to determine reductions in potential aquatic toxicity. Contaminant concentrations in water and sediment consistently decreased as the water was moving through the OWWP. Concentration-based removals were 44.2–100% for fipronil compounds, 61.8–100% for bifenthrin, and 47.3–92.7% for cyfluthrin, and the removal was attributed to sedimentation, in situ microbial degradation, and photolysis. The mitigation of these urban-use insecticides by the OWWP was similar to that of a densely vegetated constructed wetland at the same site. Therefore, OWWPs represent a low-maintenance and effective wetland configuration for large-scale water reclamation and may be particularly useful for arid and semiarid regions with favorable meteorological conditions (e.g., intense sunshine and high temperature).

Sampling rates for passive samplers exposed to a field-relevant peak of 42 organic pesticides

Pesticide concentrations in agricultural streams are often characterised by a low level of baseline exposure and episodic peak concentrations associated with heavy rainfall events. Traditional sampling methods such as grab sampling, which are still largely used in governmental monitoring, typically miss peak concentrations. Passive sampling represents a cost-efficient alternative but requires the additional determination of sampling rates to calculate time-weighted average (TWA) water concentrations from the accumulated pesticide mass in the sampler. To date, sampling rates have largely been determined in experiments with constant exposure, which does not necessarily reflect field situations. Using Empore styrene-divinylbenzene (SDB) passive sampler disks mounted in metal holders, we determined sampling rates for 42 organic pesticides, of which 27 sampling rates were lacking before. The SDB disks were in an artificial channel system exposed to a field-relevant pesticide peak. We used an open-source algorithm to estimate coefficients of equations for the accumulated pesticide mass in disks and to determine exposure time-dependent sampling rates. These sampling rates ranged from 0.02 to 0.98 L d−1 and corresponded to those from previous studies determined with constant exposure. The prediction of sampling rates using compound properties was unreliable. Hence, experiments are required to determine reliable sampling rates. We discuss the use of passive sampling to estimate peak concentrations. Overall, our study provides sampling rates and computer code to determine these under peak exposure designs and suggests that passive sampling is suitable to estimate peak pesticide concentrations in field studies.

Solar reclamation of agro-wastewater polluted with eight pesticides by heterogeneous photocatalysis using a modular facility. A case study

In this work, we have studied the removal of eight pesticides, commonly used in fruit crops, in agro-wastewater generated in commercial farms by the cleaning of trace of phytosanitary products in containers and tanks from treatment equipment. The studied pesticides were acetamiprid, cyproconazole, cyprodinil, difenoconazole, fenhexamid, hexythiazox, myclobutanil and thiamethoxam. The trials were performed in a pilot facility located in Murcia (SE of Spain), using natural sunlight and titanium dioxide (TiO2) in tandem with Na2S2O8. Five photocatalytic treatments were carried out during autumn 2017. Results show that the mean (n = 5) final amount was about 13% of the initial pesticide mass present in agro-wastewater. Therefore, we have proved that this technology could be used for tackling the elimination of pesticide residues in agro-wastewater and has favourable prospects of being applied in the water treatment sector.

Behavior of isoprothiolane and fipronil in paddy water, soil, and rice plants after nursery-box or submerged applications.

We investigated the behavior of isoprothiolane and fipronil after nursery-box application and that of isoprothiolane after submerged application in an experimental paddy field. The concentrations of the pesticides and their metabolites were monitored in paddy water, soil, and rice plants. The distribution profile for isoprothiolane mass in the field differed greatly between the nursery-box and submerged applications. The nursery-box-applied pesticides were mostly distributed in soil near the transplanted rice seedlings (root zone), versus little distribution in paddy water and rice plants (<1.1 and <0.3% of the applied mass, respectively). The residual levels in rice plants were similar to those in the root-zone soil. To estimate the soil pesticide mass, we defined a key parameter: the ratio of the root-zone area to the total area of the paddy field estimated to be 0.1 to 0.15. This parameter is important when evaluating the concentrations of nursery-box-applied pesticides in soil and rice plants.

Effect of vegetative filter strip pesticide residue degradation assumptions for environmental exposure assessments

Understanding and simulating the fate and transport of pesticides from a field to adjacent receiving water bodies is critical for estimating long-term environmental exposure concentrations (EECs) in regulatory higher-tier environmental exposure assessments (EEA). The potential of field mitigation practices like vegetative filter strips (VFS) to reduce pesticide pollution is receiving increasing attention. Previous research has proposed a modeling framework that links the US Environmental Protection Agency's (US-EPA) PRZM/EXAMS higher-tier EEA with a process-based VFS model (VFSMOD). This framework was updated to consider degradation and carryover of pesticide residue trapped in the VFS. However, there is disagreement on pesticide degradation assumptions among different regional EEA regulations (i.e. US or European Union), and in particular on how temperature and soil moisture dynamics may affect EECs. This research updated the VFS modeling framework to consider four degradation assumptions and determine if VFS residues and/or EECs differed with each assumption. Two model pesticides (mobile-labile and immobile-persistent) were evaluated for three distinct agroecological scenarios (continental row-crop agriculture, wet maritime agriculture, and dry Mediterranean intensive horticulture) with receiving water bodies and VFS lengths from 0 to 9m. The degradation assumption was important in long-term assessments to predict VFS pesticide residues (statistically different at p<0.01). However, due to the relatively small contribution of residues on the total pesticide mass moving through the VFS, degradation assumptions had a negligible impact on EECs. This indicates that, while important differences exist between EU or US EEAs, the choice of pesticide degradation assumption is not a main source of these differences.

Modeling spray drift and runoff-related inputs of pesticides to receiving water.

Pesticides move to surface water via various pathways including surface runoff, spray drift and subsurface flow. Little is known about the relative contributions of surface runoff and spray drift in agricultural watersheds. This study develops a modeling framework to address the contribution of spray drift to the total loadings of pesticides in receiving water bodies. The modeling framework consists of a GIS module for identifying drift potential, the AgDRIFT model for simulating spray drift, and the Soil and Water Assessment Tool (SWAT) for simulating various hydrological and landscape processes including surface runoff and transport of pesticides. The modeling framework was applied on the Orestimba Creek Watershed, California. Monitoring data collected from daily samples were used for model evaluation. Pesticide mass deposition on the Orestimba Creek ranged from 0.08 to 6.09% of applied mass. Monitoring data suggests that surface runoff was the major pathway for pesticide entering water bodies, accounting for 76% of the annual loading; the rest 24% from spray drift. The results from the modeling framework showed 81 and 19%, respectively, for runoff and spray drift. Spray drift contributed over half of the mass loading during summer months. The slightly lower spray drift contribution as predicted by the modeling framework was mainly due to SWAT's under-prediction of pesticide mass loading during summer and over-prediction of the loading during winter. Although model simulations were associated with various sources of uncertainties, the overall performance of the modeling framework was satisfactory as evaluated by multiple statistics: for simulation of daily flow, the Nash-Sutcliffe Efficiency Coefficient (NSE) ranged from 0.61 to 0.74 and the percent bias (PBIAS)<28%; for daily pesticide loading, NSE=0.18 and PBIAS=-1.6%. This modeling framework will be useful for assessing the relative exposure from pesticides related to spray drift and runoff in receiving waters and the design of management practices for mitigating pesticide exposure within a watershed.

Assessing the Potential Exposure of Groundwater to Pesticides: A Model Comparison

Core Ideas Numerical models were compared for transport of four pesticides in nine pedoclimatic scenarios. Conceptual uncertainty in soil physical representation of pesticide transport was assessed. HYDRUS (2D/3D) can be used as an alternative model for pesticide assessment studies. Many pesticide‐leaching studies rely on the use of numerical models that account for various physicochemical and biological processes at a range of temporal and spatial scales. In leaching assessments for the registration of pesticides in the European Union and the United States, one‐dimensional models are used that describe the vertical transport of soil water and pesticides to groundwater. One‐dimensional models are most representative for spray and broadcast applications of pesticides, but they may not be adequate for spatially nonuniform applications such as microdrip irrigation. We tested whether an advanced numerical model capable of one‐, two‐, and three‐dimensional flow and pesticide transport simulation [HYDRUS (2D/3D)] provides results consistent with one‐dimensional numerical models commonly used for pesticide registration (PEARL, PELMO). Model comparison was used to assess conceptual uncertainty in soil physical representation of pesticide transport among numerical models across a range of applications. Simulations of soil water flow and pesticide and heat transport were conducted for four different hypothetical pesticides and nine European regulatory standard pedoclimatic scenarios (FOCUS). The results show that the predicted annual amount of pesticide mass leached below the depth of 1 m, for all substances, locations, and simulation years, was on the same order of magnitude among the three models. Additionally, the simulated 80th percentile of annual pesticide concentrations at the 1‐m depth was not statistically different among models. HYDRUS (2D/3D) can, therefore, be used as an alternative model for pesticide assessment studies and provides a conceptual framework consistent with PEARL and PELMO but capable of two‐ and three‐dimensional applications as well.

Mitigation of polar pesticides across a vegetative filter strip. A mesocosm study.

Vegetated filter strips (VFSs) are planted at the edge of agricultural fields to reduce pesticide run-off and its consequent potential toxicological effects on ecosystem biota; however, little attention has been paid to date to the attenuation of highly polar and ionisable pesticides such as phenoxyacid herbicides. This study assesses the effect of soil moisture, run-off flow and vegetation on the attenuation of MCPA, mecoprop, dicamba, dichlorprop, fenitrothion, atrazine and simazine by VFSs. Reactors measuring 5m long by 0.1m wide were each filled with 60kg of soil from a real field VFS. VFSs planted with Phragmites australis and unvegetated control reactors were assessed. After a simulated rainfall event of 50mm, two hydraulic loading rates (HLRs) were assessed (1 and 2cmh-1). These results were compared to those from the same systems under water-saturated conditions. The results show that VFSs reduced the peak inlet concentration and pesticide mass by more than 90% and that the presence of vegetation increased that attenuation (82-90% without vegetation and 90-93% with vegetation, on average). The laboratory-scale study showed that such attenuation was due to sorption into the soil. The toxicity units of pesticides fell by more than 90% in all cases, except under the water-saturated conditions, in which the decrease was lower (16 vs 54%, for unvegetated and vegetated reactors). Therefore, the presence of vegetation was shown to be effective for reducing mass discharge of ionisable and highly polar pesticides into surface-water bodies.

Influence of commercial formulation on leaching of four pesticides through soil

Studies with small soil columns (2cm i.d.×5.4cm depth) compared leaching of four pesticides added either as technical material or as commercial formulations. Pesticides were selected to give a gradient of solubility in water between 7 and 93mgL−1, comprising azoxystrobin (emulsifiable concentrate, EC, and suspension concentrate, SC), cyproconazole (SC), propyzamide (SC) and triadimenol (EC). Columns of sandy loam soil were leached with 6 pore volumes of 0.01M CaCl2 either 1 or 7days after treatment. Separate experiments evaluated leaching of triadimenol to full breakthrough following addition of 18 pore volumes of 0.01M CaCl2. The mass of pesticide leached from columns treated with commercial formulation was significantly larger than that from columns treated with technical material for all compounds studied and for both leaching intervals (two-sided t-tests, p<0.001). This difference was conserved when triadimenol was leached to full breakthrough with 79±1.2 and 61±3.1% of applied triadimenol leached from columns treated with formulated and technical material, respectively. There were highly significant effects of formulation for all pesticides (two-way ANOVA, p<0.001), whereas leaching interval was only significant for azoxystrobin EC formulation and cyproconazole (p<0.001 and 0.021, respectively) with greater leaching when irrigation commenced 1day after treatment. Leaching of azoxystrobin increased in the order technical material (6.0% of applied pesticide)<SC formulation (8.5–9.1% of applied)<EC formulation (15.8–21.0% of applied). The relative difference between leaching of formulated and technical pesticide increased with pesticide solubility in water, increasing from a factor of 1.4 for the SC formulation of azoystrobin to 4.3 for the SC formulation of triadimenol. Experimental systems differ markedly from field conditions (small columns with intense irrigation). Nevertheless, results indicate the need to consider further the influence of co-formulants in pesticide formulations on behaviour of the active ingredient in soil.

Predicting runoff induced mass loads in urban watersheds: Linking land use and pyrethroid contamination

Pyrethroid pesticide mass loadings in the Ballona Creek Watershed were calculated using the volume-concentration method with a Geographic Information Systems (GIS) to explore potential relationships between urban land use, impervious surfaces, and pyrethroid runoff flowing into an urban stream. A calibration of the GIS volume-concentration model was performed using 2013 and 2014 wet-weather sampling data. Permethrin and lambda-cyhalothrin were detected as the highest concentrations; deltamethrin, lambda-cyhalothrin, permethrin and cyfluthrin were the most frequently detected synthetic pyrethroids. Eight neighborhoods within the watershed were highlighted as target areas based on a Weighted Overlay Analysis (WOA) in GIS. Water phase concentration of synthetic pyrethroids (SPs) were calculated from the reported usage. The need for stricter BMP and consumer product controls was identified as a possible way of reducing the detections of pyrethroids in Ballona Creek. This model has significant implications for determining mass loadings due to land use influence, and offers a flexible method to extrapolate data for a limited amount of samplings for a larger watershed, particularly for chemicals that are not subject to environmental monitoring. Offered as a simple approach to watershed management, the GIS-volume concentration model has the potential to be applied to other target pesticides and is useful for simulating different watershed scenarios. Further research is needed to compare results against other similar urban watersheds situated in mediterranean climates.

Integration of transport concepts for risk assessment of pesticide erosion

Environmental contamination by agrochemicals has been a large problem for decades. Pesticides are transported in runoff and remain attached to eroded soil particles, posing a risk to water and soil quality and human health. We have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation.

Do constructed wetlands in grass strips reduce water contamination from drained fields?

This study evaluates the efficiency of two small constructed wetlands installed in the regulatory grass strips between a drained plot and a river. The observed nitrate removal efficiencies were independent of the season or type of constructed wetland and ranged from 5.4 to 10.9% of the inlet amounts. The pesticide mass budgets ranged from −618.5 to 100%, depending on the molecule. The negative efficiencies were attributed to runoff and remobilization. In contrast, the highest efficiencies were associated with pesticides with high Koc and low DT50 (half-life) values, suggesting sorption and degradation. However, the effectiveness of these wetlands is limited for pesticides with low Koc or high DT50 values; thus, the use of these molecules must be reduced. Increasing the number of these small, inexpensive and low-maintenance wetlands in the agricultural landscape would reduce the level of water pollution whilst preserving the extent of cultivated land, but their long-term effectiveness should be evaluated.

Evaluation of Three Models for Simulating Pesticide Runoff from Irrigated Agricultural Fields.

Three models were evaluated for their accuracy in simulating pesticide runoff at the edge of agricultural fields: Pesticide Root Zone Model (PRZM), Root Zone Water Quality Model (RZWQM), and OpusCZ. Modeling results on runoff volume, sediment erosion, and pesticide loss were compared with measurements taken from field studies. Models were also compared on their theoretical foundations and ease of use. For runoff events generated by sprinkler irrigation and rainfall, all models performed equally well with small errors in simulating water, sediment, and pesticide runoff. The mean absolute percentage errors (MAPEs) were between 3 and 161%. For flood irrigation, OpusCZ simulated runoff and pesticide mass with the highest accuracy, followed by RZWQM and PRZM, likely owning to its unique hydrological algorithm for runoff simulations during flood irrigation. Simulation results from cold model runs by OpusCZ and RZWQM using measured values for model inputs matched closely to the observed values. The MAPE ranged from 28 to 384 and 42 to 168% for OpusCZ and RZWQM, respectively. These satisfactory model outputs showed the models' abilities in mimicking reality. Theoretical evaluations indicated that OpusCZ and RZWQM use mechanistic approaches for hydrology simulation, output data on a subdaily time-step, and were able to simulate management practices and subsurface flow via tile drainage. In contrast, PRZM operates at daily time-step and simulates surface runoff using the USDA Soil Conservation Service's curve number method. Among the three models, OpusCZ and RZWQM were suitable for simulating pesticide runoff in semiarid areas where agriculture is heavily dependent on irrigation.

An Improved Indirect Procedure for Estimating Pesticide Volatility from Field Trials.

Conventional indirect approaches for estimating pesticide volatility from agricultural fields require an air dispersion model and near-field, temporal air concentration measurements. The model pesticide flux profile is chosen such that field observations are recovered. Ross et al. (1996) first proposed a back-calculation method (BCM) using a single iteration of the Industrial Source Complex Short Term (ISCST) parameterized by a unit source flux. The unit flux is updated by scaling with the slope of a linear regression line between model predictions and actual field observations at each measured time point and location, yielding an estimate for the field flux that occurred over the sampling period. The BCM is expanded using a downhill simplex optimization procedure requiring many ISCST iterations to consecutively adjust the volatility flux rate such that the sum of the squared residuals between predicted and measured air concentrations is minimized (denoted as BCMO). The BCMO is ideally suited for comparing the volatility of different pesticide formulations of the same active from field studies performed simultaneously. Comparison of the BCM and BCMO from field trials containing single (Texas) and multiple simultaneously treated fields (Indiana) are provided for pesticides ranging from low to high volatility. The advanced BCMO is a better alternative than the original BCM, as shown by closer model predictions to measured air concentrations. A major advantage of the BCMO is the ability to extract unique flux source strengths for each field when multiple fields are present and treated consecutively and contiguously with each field emitting pesticide mass at different rates.

Does mechanistic modeling of filter strip pesticide mass balance and degradation processes affect environmental exposure assessments?

Vegetative filter strips (VFS) are a widely adopted practice for limiting pesticide transport from adjacent fields to receiving waterbodies. The efficacy of VFS depends on site-specific input factors. To elucidate the complex and non-linear relationships among these factors requires a process-based modeling framework. Previous research proposed linking existing higher-tier environmental exposure models with a well-tested VFS model (VFSMOD). However, the framework assumed pesticide mass stored in the VFS was not available for transport in subsequent storm events. A new pesticide mass balance component was developed to estimate surface pesticide residue trapped in the VFS and its degradation between consecutive runoff events. The influence and necessity of the updated framework on acute and chronic estimated environmental concentrations (EECs) and percent reductions in EECs were investigated across three, 30-year U.S. EPA scenarios: Illinois corn, California tomato, and Oregon wheat. The updated framework with degradation predicted higher EECs than the existing framework without degradation for scenarios with greater sediment transport, longer VFS lengths, and highly sorbing and persistent pesticides. Global sensitivity analysis (GSA) assessed the relative importance of mass balance and degradation processes in the context of other input factors like VFS length (VL), organic-carbon sorption coefficient (Koc), and soil and water half-lives. Considering VFS pesticide residue and degradation was not important if single, large runoff events controlled transport, as is typical for higher percentiles considered in exposure assessments. Degradation processes become more important when considering percent reductions in acute or chronic EECs, especially under scenarios with lower pesticide losses.

Fate of micropollutants during sewage sludge disintegration by low-frequency ultrasound

The degradation of micropollutants (pesticides) absorbed in agro-food industrial sewage sludge was investigated during its excess reduction by disintegration with ultrasound treatment. Sludge sonication (24kHz and 323W) was performed in batch mode in a stainless steel ultrasonic flow-through reactor connected to a recirculation tank. The maximum sludge disintegration was reached by supplying 0.87MJL−1 ultrasound dose (UD) giving rise to 68.7% solubilisation of the carbon content in the disintegrated biomass. The sonicated sludge was biodegradable, thus able to be returned as feed in the secondary wastewater treatment. The ultrasound (US) treatment resulted in a significant reduction in the sludge pesticide content (90% of the total pesticide mass was removed), therefore preventing pollutant accumulation in the sludge. Investigation into the sono-degradation of three characteristic pesticides (thiabendazole, acetamiprid and imazalil) revealed the formation of transformation products (TPs) already reported in studies on the degradation of these compounds by advanced oxidation processes, thus confirming that ultrasonication involves hydroxyl radical reactions. Our results show that this US treatment for the excess sludge reduction is also efficient for pesticides and their TPs removal.

Life cycle human health impacts of 875 pesticides

Residues in field crops grown and harvested for human consumption are the main contributor to overall human exposure toward agricultural pesticides for the general population. However, exposure from crop residues is currently not considered in life cycle assessment practice. We therefore present a consistent framework for characterizing human toxicological impacts associated with pesticides applied to agricultural crops in the frame of life cycle impact assessment based on state-of-the-art data and methods. We combine a dynamic multicrop plant uptake model designed for evaluating human exposure to residues for a wide range of pesticide-crop combinations with latest findings of pesticide dissipation kinetics in crops and post-harvest food processing. Outcome is a set of intake fractions and characterization factors for 875 organic pesticides and six major food crops along with specific confidence intervals for each factor. Intake fractions aggregating exposure via crop residues and exposure via fractions lost to air and soil for pesticides applied to agricultural crops vary between 10−8 and 10−1 kg intake per kilogram applied as a function of pesticide and crop. Intake fractions are typically highest for lettuce and tomato and lowest for potato due to differences in application times before crop harvest and soil as additional barrier for uptake into potato tubers. Uncertainty in intake fractions is mainly associated with dissipation dynamics in crops, where results demonstrate that using pesticide- and crop-specific data is crucial. Combined with the uncertainty in effect modeling, characterization factors per pesticide and crop show squared geometric mean standard deviations ranging from 38 to 15,560 over a variability range across pesticide-crop combinations of 10 orders of magnitude. Our framework is operational for use in current life cycle impact assessment models, is made available for USEtox, and closes an important gap in the assessment of human exposure to pesticides. For ready use in life cycle assessment studies, we present pesticide-crop combination-specific characterization factors normalized to pesticide mass applied and provide default data for application times and loss due to post-harvest food processing. When using our data, we emphasize the need to consult current pesticide regulation, since each pesticide is registered for use on certain crops only, which varies between countries.