Ronnie Juraske

Life Cycle Inventory and Carbon and Water FoodPrint of Fruits and Vegetables: Application to a Swiss Retailer

Food production and consumption is known to have significant environmental impacts. In the present work, the life cycle assessment methodology is used for the environmental assessment of an assortment of 34 fruits and vegetables of a large Swiss retailer, with the aim of providing environmental decision-support to the retailer and establishing life cycle inventories (LCI) also applicable to other case studies. The LCI includes, among others, seedling production, farm machinery use, fuels for the heating of greenhouses, irrigation, fertilizers, pesticides, storage and transport to and within Switzerland. The results show that the largest reduction of environmental impacts can be achieved by consuming seasonal fruits and vegetables, followed by reduction of transport by airplane. Sourcing fruits and vegetables locally is only a good strategy to reduce the carbon footprint if no greenhouse heating with fossil fuels is involved. The impact of water consumption depends on the location of agricultural production. For some crops a trade-off between the carbon footprint and the induced water stress is observed. The results were used by the retailer to support the purchasing decisions and improve the supply chain management.

Environmental impacts of organic and conventional agricultural products – Are the differences captured by life cycle assessment?

Comprehensive assessment tools are needed that reliably describe environmental impacts of different agricultural systems in order to develop sustainable high yielding agricultural production systems with minimal impacts on the environment. Today, Life Cycle Assessment (LCA) is increasingly used to assess and compare the environmental sustainability of agricultural products from conventional and organic agriculture. However, LCA studies comparing agricultural products from conventional and organic farming systems report a wide variation in the resource efficiency of products from these systems. The studies show that impacts per area farmed land are usually less in organic systems, but related to the quantity produced impacts are often higher. We reviewed 34 comparative LCA studies of organic and conventional agricultural products to analyze whether this result is solely due to the usually lower yields in organic systems or also due to inaccurate modeling within LCA. Comparative LCAs on agricultural products from organic and conventional farming systems often do not adequately differentiate the specific characteristics of the respective farming system in the goal and scope definition and in the inventory analysis. Further, often only a limited number of impact categories are assessed within the impact assessment not allowing for a comprehensive environmental assessment. The most critical points we identified relate to the nitrogen (N) fluxes influencing acidification, eutrophication, and global warming potential, and biodiversity. Usually, N-emissions in LCA inventories of agricultural products are based on model calculations. Modeled N-emissions often do not correspond with the actual amount of N left in the system that may result in potential emissions. Reasons for this may be that N-models are not well adapted to the mode of action of organic fertilizers and that N-emission models often are built on assumptions from conventional agriculture leading to even greater deviances for organic systems between the amount of N calculated by emission models and the actual amount of N available for emissions. Improvements are needed regarding a more precise differentiation between farming systems and regarding the development of N emission models that better represent actual N-fluxes within different systems. We recommend adjusting N- and C-emissions during farmyard manure management and farmyard manure fertilization in plant production to the feed ration provided in the animal production of the respective farming system leading to different N- and C-compositions within the excrement. In the future, more representative background data on organic farming systems (e.g. N content of farmyard manure) should be generated and compiled so as to be available for use within LCA inventories. Finally, we recommend conducting consequential LCA - if possible - when using LCA for policy-making or strategic environmental planning to account for different functions of the analyzed farming systems.

Uptake and persistence of pesticides in plants: measurements and model estimates for imidacloprid after foliar and soil application.

The uptake and persistence behaviour of the insecticide imidacloprid in tomato plants treated by (i) foliar spray application and (ii) soil irrigation was studied using two plant uptake models. In addition to a pesticide deposition model, a dynamic root uptake and translocation model was developed, and both models predict residual concentrations of pesticides in or on fruits. The model results were experimentally validated. The fraction of imidacloprid ingested by the human population is on average 10(-2) to 10(-6), depending on the time between pesticide application and ingestion, the processing step, and the application method. Model and experimentally derived intake fractions deviated by less than a factor of 2 for both application techniques. Total imidacloprid residues were up to five times higher in plants treated by foliar spray application than by soil irrigation. However, peeling tomatoes treated by spray application reduces the human intake fraction by up to three orders of magnitude. Model calculations suggest that drip-irrigation in a closed hydroponic system minimizes worker and consumer exposure to pesticides and prevents runoff of pesticide by spray drift and leaching into the environment.

Life cycle human toxicity assessment of pesticides: comparing fruit and vegetable diets in Switzerland and the United States.

Food consumption represents the dominant exposure pathway of the general public to pesticides. In this paper, we characterize the lifelong cumulative human health damage from ingestion of pesticides contained in fruits and vegetables in Switzerland and the United States. We evaluated pesticide residues in 62,151 food samples. Chemical specific concentrations were combined with pesticide emission data and information on country-specific diets and chemical toxicity to assess the human health impacts of 51 food commodities and national average diets. Furthermore, a list of characterization factors for pesticide ingestion via food was calculated for use in life cycle impact assessment. On average, the Swiss population takes in via food ingestion 0.41g of every 1kg of pesticide applied during agricultural cultivation. The corresponding value in the United States is 0.51. Intake fractions based on experimental monitoring data were compared with outputs from the USEtox model for life cycle impact assessment of toxic substances. The modeled intake fractions were underestimated by up to two orders of magnitude. However, even when using the monitored residue concentration data, the absolute health damage via fruits and vegetable ingestion was small: The potential lifelong damage of pesticides is estimated to be only 4.2 and 3.2 min of life lost per person in Switzerland and the United States, respectively. The results of this study indicate that pesticide intake due to the ingestion of fruits and vegetables consumed in Switzerland and the United States does not lead to significant human health damages.

Dynamic Multicrop Model to Characterize Impacts of Pesticides in Food

A new dynamic plant uptake model is presented to characterize health impacts of pesticides applied to food crops, based on a flexible set of interconnected compartments. We assess six crops covering a large fraction of the worldwide consumption. Model estimates correspond well with observed pesticide residues for 12 substance-crop combinations, showing residual errors between a factor 1.5 and 19. Human intake fractions, effect and characterization factors are provided for use in life cycle impact assessment for 726 substance-crop combinations and different application times. Intake fractions typically range from 10⁻² to 10⁻⁸ kg(intake) kg(applied)⁻¹. Human health impacts vary up to 9 orders of magnitude between crops and 10 orders of magnitude between pesticides, stressing the importance of considering interactions between specific crop-environments and pesticides. Time between application and harvest, degradation half-life in plants and residence time in soil are driving the evolution of pesticide masses.We demonstrate that toxicity potentials can be reduced up to 99% by defining adequate pesticide substitutions. Overall, leafy vegetables only contribute to 2% of the vegetal consumption, but due to later application times and higher intake fractions may nevertheless lead to impacts comparable or even higher than via the larger amount of ingested cereals.

Estimating Half-Lives for Pesticide Dissipation from Plants

Pesticide risk and impact assessment models critically rely on and are sensitive to information describing dissipation from plants. Despite recent progress, experimental data are not available for all relevant pesticide-plant combinations, and currently no model predicting plant dissipation accounts for the influence of substance properties, plant characteristics, temperature, and study conditions. In this study, we propose models to estimate half-lives for pesticide dissipation from plants and provide recommendations for how to use our results. On the basis of fitting experimental dissipation data with reported average air temperatures, we estimated a reaction activation energy of 14.25 kJ/mol and a temperature coefficient Q10 of 1.22 to correct dissipation from plants for the influence of temperature. We calculated a set of dissipation half-lives for 333 substances applied at 20 °C under field conditions. Half-lives range from 0.2 days for pyrethrins to 31 days for dalapon. Parameter estimates are provided to correct for specific plant species, temperatures, and study conditions. Finally, we propose a predictive regression model for pesticides without available measured dissipation data to estimate half-lives based on substance properties at the level of chemical substance class. Estimated half-lives from our study are designed to be applied in risk and impact assessment models to either directly describe dissipation or as first proxy for describing degradation.

Pesticide uptake in potatoes: model and field experiments.

A dynamic model for uptake of pesticides in potatoes is presented and evaluated with measurements performed within a field trial in the region of Boyacá, Colombia. The model takes into account the time between pesticide applications and harvest, the time between harvest and consumption, the amount of spray deposition on soil surface, mobility and degradation of pesticide in soil, diffusive uptake and persistence due to crop growth and metabolism in plant material, and loss due to food processing. Food processing steps included were cleaning, washing, storing, and cooking. Pesticide concentrations were measured periodically in soil and potato samples from the beginning of tuber formation until harvest. The model was able to predict the magnitude and temporal profile of the experimentally derived pesticide concentrations well, with all measurements falling within the 90% confidence interval. The fraction of chlorpyrifos applied on the field during plant cultivation that eventually is ingested by the consumer is on average 10(-4)-10(-7), depending on the time between pesticide application and ingestion and the processing step considered.

Parameterization models for pesticide exposure via crop consumption.

An approach for estimating human exposure to pesticides via consumption of six important food crops is presented that can be used to extend multimedia models applied in health risk and life cycle impact assessment. We first assessed the variation of model output (pesticide residues per kg applied) as a function of model input variables (substance, crop, and environmental properties) including their possible correlations using matrix algebra. We identified five key parameters responsible for between 80% and 93% of the variation in pesticide residues, namely time between substance application and crop harvest, degradation half-lives in crops and on crop surfaces, overall residence times in soil, and substance molecular weight. Partition coefficients also play an important role for fruit trees and tomato (Kow), potato (Koc), and lettuce (Kaw, Kow). Focusing on these parameters, we develop crop-specific models by parametrizing a complex fate and exposure assessment framework. The parametric models thereby reflect the frameworks physical and chemical mechanisms and predict pesticide residues in harvest using linear combinations of crop, crop surface, and soil compartments. Parametric model results correspond well with results from the complex framework for 1540 substance-crop combinations with total deviations between a factor 4 (potato) and a factor 66 (lettuce). Predicted residues also correspond well with experimental data previously used to evaluate the complex framework. Pesticide mass in harvest can finally be combined with reduction factors accounting for food processing to estimate human exposure from crop consumption. All parametric models can be easily implemented into existing assessment frameworks.

The Glasgow consensus on the delineation between pesticide emission inventory and impact assessment for LCA

PurposePesticides are applied to agricultural fields to optimise crop yield and their global use is substantial. Their consideration in life cycle assessment (LCA) is affected by important inconsistencies between the emission inventory and impact assessment phases of LCA. A clear definition of the delineation between the product system model (life cycle inventory—LCI, technosphere) and the natural environment (life cycle impact assessment—LCIA, ecosphere) is missing and could be established via consensus building.MethodsA workshop held in 2013 in Glasgow, UK, had the goal of establishing consensus and creating clear guidelines in the following topics: (1) boundary between emission inventory and impact characterisation model, (2) spatial dimensions and the time periods assumed for the application of substances to open agricultural fields or in greenhouses and (3) emissions to the natural environment and their potential impacts. More than 30 specialists in agrifood LCI, LCIA, risk assessment and ecotoxicology, representing industry, government and academia from 15 countries and four continents, met to discuss and reach consensus. The resulting guidelines target LCA practitioners, data (base) and characterisation method developers, and decision makers.Results and discussionThe focus was on defining a clear interface between LCI and LCIA, capable of supporting any goal and scope requirements while avoiding double counting or exclusion of important emission flows/impacts. Consensus was reached accordingly on distinct sets of recommendations for LCI and LCIA, respectively, recommending, for example, that buffer zones should be considered as part of the crop production system and the change in yield be considered. While the spatial dimensions of the field were not fixed, the temporal boundary between dynamic LCI fate modelling and steady-state LCIA fate modelling needs to be defined.Conclusions and recommendationsFor pesticide application, the inventory should report pesticide identification, crop, mass applied per active ingredient, application method or formulation type, presence of buffer zones, location/country, application time before harvest and crop growth stage during application, adherence with Good Agricultural Practice, and whether the field is considered part of the technosphere or the ecosphere. Additionally, emission fractions to environmental media on-field and off-field should be reported. For LCIA, the directly concerned impact categories and a list of relevant fate and exposure processes were identified. Next steps were identified: (1) establishing default emission fractions to environmental media for integration into LCI databases and (2) interaction among impact model developers to extend current methods with new elements/processes mentioned in the recommendations.

Exposure to engineered nanoparticles: Model and measurements for accident situations in laboratories

In the life cycle of engineered nanoparticles (ENP), their manufacturing requires particular attention because of unwanted potential ENP emissions to workplaces. We simulated three scenarios of equipment failure during gas phase production of nanoparticles in a laboratory. The emission plume of nanoparticles was tracked with high spatial and temporal resolution by 10 measurement devices. While under normal production conditions, no elevated ENP concentrations were observed, worst case scenarios led to homogeneous indoor ENP concentrations of up to 10(6)cm(-3) in a 300m(3) production room after only 60s. The fast dispersal in the room was followed by an exponential decrease in number concentration after the emission event. Under conditions like those observed - rapid dispersal and good mixing - a single measurement device alone can provide valuable information for an ENP exposure assessment. A one-box model adequately reflected measured number concentrations (r(2)>0.99). The ENP emission rates to the workplace were estimated between 2.5·10(11) and 6·10(12)s(-1) for the three emission scenarios. The worst case emission rate at the production zone was also estimated at 2·10(13)s(-1) with a stoichiometric calculation based on the precursor input, density and particle size. ENP intake fractions were 3.8-5.1·10(-4) inhaled ENP per produced ENP in the investigated setting. These could only be substantially lowered by leaving the production room within a few minutes after the emission event.