Pesticide application, educational treatment and infectious respiratory diseases: A mechanistic model with two impulsive controls.

In this paper, we develop and analyze an SIS-type epidemiological-mathematical model of the interaction between pesticide use and infectious respiratory disease transmission for investigating the impact of pesticide intoxication on the spread of these types of diseases. We further investigate the role of educational treatment for appropriate pesticide use on the transmission dynamics. Two impulsive control events are proposed: pesticide use and educational treatment. From the proposed model, it was obtained that the rate of forgetfulness towards educational treatment is a determining factor for the reduction of intoxicated people, as well as for the reduction of costs associated with educational interventions. To get reduced intoxications, the population's fraction to which is necessary to apply the educational treatment depends on its individual effectiveness level and the educational treatments' forgetfulness rate. In addition, the turnover of agricultural workers plays a fundamental role in the dynamics of agrotoxic use, particularly in the application of educational treatment. For illustration, a flu-like disease with a basic reproductive number below the epidemic threshold of 1.0 is shown can acquire epidemic potential in a population at risk of pesticide exposure. Hence, our findings suggest that educational treatment targeting pesticide exposure is an effective tool to reduce the transmission rate of an infectious respiratory disease in a population exposed to the toxic substance.

Using ex-ante economic evaluation to inform research priorities in pesticide self-poisoning prevention: the case of a shop-based gatekeeper training programme in rural Sri Lanka.

OBJECTIVES: Suicide by pesticide self-poisoning is a major public health challenge in low- and middle-income countries. While effectiveness studies are required to test alternative prevention approaches, economic evidence is lacking to inform decision-making in research priority setting. Therefore, this study aimed to estimate the costs of a shop-based gatekeeper training programme for pesticide vendors seeking to prevent pesticide self-poisoning in rural Sri Lanka and assess its potential for cost-effectiveness. METHODS: Ex-ante cost and cost-effectiveness threshold (CET) analyses were performed from a governmental perspective based on a three-year analytic horizon, using 'no programme' as a comparator. A programme model targeting all 535 pesticide shops in the North Central Province and border areas was applied. Total programme costs (TPC) were estimated in 2019 USD using an ingredients approach and 3% annual discounting. The Sri Lankan gross domestic product per capita and life years saved were used as CET and effectiveness measure, respectively. Sensitivity analyses were performed. RESULTS: TPC were estimated at 31 603.03 USD. TPC were sensitive to cost changes of training material and equipment and the programme lifetime. The programme needs to prevent an estimated 0.23 fatal pesticide self-poisoning cases over three years to be considered cost-effective. In the sensitivity analyses, the highest number of fatal cases needed to be prevented to obtain cost-effectiveness was 4.55 over three years. CONCLUSIONS: From an economic perspective, the programme has a very high potential to be cost-effective. Research assessing its effectiveness should therefore be completed, and research analysing its transferability to other settings prioritised.

OBJECTIFS: Le suicide par auto-intoxication par les pesticides est un défi majeur de santé publique dans les pays à revenu faible ou intermédiaire. Bien que des études d'efficacité soient nécessaires pour tester d'autres approches de prévention, les données économiques manquent pour informer la prise de décision dans les priorités de recherche. Par conséquent, cette étude visait à estimer les coûts d'un programme de formation des vendeurs dans les magasins de pesticides visant à prévenir l'auto-intoxication par les pesticides dans les régions rurales du Sri Lanka et à évaluer son potentiel de rentabilité. MÉTHODES: Les analyses ex-ante des coûts et des seuils de rentabilité (SR) ont été réalisées dans une perspective gouvernementale sur la base d'un horizon analytique de trois ans, en utilisant «l'absence de programme¼ comme comparateur. Un modèle de programme ciblant les 535 magasins de pesticides de la province du Centre-Nord et des zones frontalières a été appliqué. Les coûts totaux du programme (CTP) ont été estimés en USD 2019 en utilisant une approche d'ingrédients et une remise annuelle de 3%. Le produit intérieur brut sri-lankais par habitant et les années de vie sauvées ont été utilisés comme SR et mesure d'efficacité, respectivement. Des analyses de sensibilité ont été effectuées. RÉSULTATS: le CTP a été estimé à 31.603,03 USD. Le CTP était sensible aux changements de coût du matériel et de l'équipement de formation et de la durée de vie du programme. Le programme devrait prévenir environ 0,23 cas d'auto-intoxication mortelle par des pesticide sur trois ans pour être considéré comme rentable. Dans les analyses de sensibilité, le plus grand nombre de cas mortels à prévenir pour obtenir une rentabilité était de 4,55 sur trois ans. CONCLUSIONS: D'un point de vue économique, le programme a un potentiel très élevé pour être rentable. La recherche évaluant son efficacité doit donc être complétée et la recherche analysant sa transférabilité à d'autres contextes doit être priorisée.

Factors associated with purchasing pesticide from shops for intentional self-poisoning in Sri Lanka.

OBJECTIVE: In South Asia, up to one in five individuals who ingest pesticides for self-poisoning and survive purchased them from a shop immediately prior to the event. Thus far, no research has taken place to determine whether interventions implemented through the pesticide sellers might be acceptable or effective, despite the hundreds of thousands of such risk purchases each year. We aimed to investigate factors associated with purchasing pesticides for self-poisoning in Sri Lanka. METHODS: We used a case-control study. Cases (n = 50) were individuals who ingested pesticides after purchasing them for the act, and controls (n = 200) were customers who bought pesticides but did not use them for self-harm. Logistic regression analysis was used to assess socio-demographic and purchase-specific risk factors. RESULTS: Alcohol intoxication (adjusted odds ratios [AOR] 36.5, 95% confidence intervals [CI] 1.7-783.4) and being a non-farmer AOR 13.3, 95% CI 1.8-99.6 were the main distinguishing factors when purchasing pesticides for self-poisoning. The positive predictive values were 93.3% (95% CI 68.0-99.8%) and 88.2% (95% CI 72.5-96.7%), respectively. One and/or other of these factors characterised 72.0% of cases but only 2.5% controls. CONCLUSION: While results need to be interpreted cautiously, sales restrictions to prevent alcohol-intoxicated persons and non-farmers purchasing pesticides for self-poisoning may be effective.

OBJECTIF: En Asie du Sud, jusqu'à une personne sur cinq qui ingère des pesticides pour s'auto­intoxiquer et survi les a achetés dans un magasin immédiatement avant l'événement. Jusqu'à présent, aucune recherche n'a eu lieu pour déterminer si les interventions mises en œuvre chez les vendeurs de pesticides pourraient être acceptables ou efficaces, malgré les centaines de milliers d'achats à risque chaque année. Nous visions à étudier les facteurs associés à l'achat de pesticides pour l'auto­intoxication au Sri Lanka. MÉTHODES: Nous avons utilisé une étude cas­témoins. Les cas (n = 50) étaient des personnes qui avaient ingéré des pesticides après les avoir achetés pour l'acte et les témoins (n = 200) étaient des clients qui achetaient des pesticides mais ne les utilisaient pas pour se faire du mal. Une analyse de régression logistique a été utilisée pour évaluer les facteurs de risque sociodémographiques et spécifiques à l'achat. RÉSULTATS: L'intoxication alcoolique (rapport de cotes ajusté [AOR] 36,5, intervalles de confiance à 95% [IC] 1,7­783,4) et étant un non­agriculteur AOR 13,3 ; IC95%: 1,8­99,6 étaient les principaux facteurs distinctifs lors de l'achat de pesticides pour l'auto­intoxication. Les valeurs prédictives positives étaient respectivement de 93,3% (IC95%: 68,0% ­99,8%) et 88,2% (IC95%: 72,5% ­96,7%). L'un et/ou l'autre de ces facteurs caractérisaient 72,0% des cas mais seulement 2,5% des témoins. CONCLUSION: Bien que les résultats doivent être interprétés avec prudence, des restrictions de vente visant à empêcher les personnes intoxiquées à l'alcool et les non­agriculteurs d'acheter des pesticides pour l'auto­intoxication peuvent être efficaces.

Estimating the government health-care costs of treating pesticide poisoned and pesticide self-poisoned patients in Sri Lanka.

Background: Pesticide self-poisoning as a method of suicide is a major global health problem.Objectives: To estimate the cost and per patient cost of treating pesticide self-poisoning at different hospital levels in a Sri Lankan district, and to examine the distribution of cost components. Another objective was to investigate changes in total cost of treatment of pesticide poisoning for all causes at different administrative levels in Sri Lanka in 2005 and 2015.Methods: The economic framework was a costing analysis, adopting a government perspective. Cost data were collected prospectively over a 4-month period in 2016 for patients admitted for pesticide self-poisoning to six hospitals in the Anuradhapura District. Assumption-based scenario analyses were run to determine changes in total pesticide poisoning treatment costs.Results: We included 67 self-poisoned patients in the study. The total cost of treatment was US$ 5,714 at an average treatment cost of US$ 85.3 (9.7-286.6) per patient (across all hospital levels). Hospital costs constituted 67% of the total cost for treating self-poisoning cases and patient-specific costs accounted for 29%. Direct cost of patient hospital transfer constituted the smallest share of costs (4%) but accounted for almost half of the total costs at primary level. The estimated total cost of treating all causes of pesticide poisoning in Sri Lanka was US$ 2.5 million or 0.19% of the total government health expenditure (GHE) in 2015.Conclusion: Our findings indicate that the average per patient cost of pesticide self-poisoning treatment has increased while the total cost of pesticide poisoning treatment as a percentage of the total GHE in Sri Lanka has declined over the past decade. A continuous focus on banning the most hazardous pesticides available would likely further drive down the cost of pesticide self-poisoning and pesticide poisoning to the government.

Farm Machine Use and Pesticide Expenditure in Maize Production: Health and Environment Implications.

Although chemical pesticide use has increased agricultural productivity, it has caused adverse effects on human health and the environment. For example, pesticide exposure may result in the incidence of a human health condition (e.g., heart disease, immune disorders, cancer, and damaged skin) and it can pollute air, water, and soil conditions and damage biodiversity. Mitigating the negative externalities associated with pesticide use is essential to improve human health and environmental performance. In this study, we are trying to explore whether farm machine use reduces pesticide expenditure by analyzing farm household survey data collected from 493 maize farmers in China. An endogenous switching regression model is employed to address the sample selection bias issue associated with voluntary farm machine use. The empirical results reveal that farm machine use exerts a negative and statistically significant impact on pesticide expenditure. The findings highlight the important role of farm machines in helping reduce pesticide expenditure, which is, in turn, beneficial for improving human health conditions and environmental performance.

Socioeconomic, agricultural, and individual factors influencing farmers' perceptions and willingness of compost production and use: an evidence from Wadi al-Far'a Watershed-Palestine.

In Palestine, open dumping and/or burning the waste, including agricultural waste, are prevalent practices resulting in emitting leachate and acidifying greenhouse gases. Composting the agricultural waste can reduce emissions and provide 'compost' as an organic fertilizer and soil amendment; yet, it has not been implemented at the national level. To develop a local marketing strategy for compost, this study views a need to identify farmers' perceptions and willingness of compost production and use in agriculture and examine various socioeconomic, agricultural, and individual factors shaping them. The case of Wadi al-Far'a watershed (WFW) is investigated, where farmers practice inappropriate waste disposal and overuse of agrochemicals. A semi-structured questionnaire is administered to 409 farmers through face-to-face interviews. Descriptive statistics, bivariate analyses, Chi-square test, and binary logistic regression are used for data analysis. High acceptance level (84%) is disclosed among farmers in WFW for the hypothetical idea of producing and using compost. Farmers also have high, yet lower, willingness level (63.6%) of the more salient option of producing compost themselves and using it in agriculture. Tenure systems, large cultivated areas, rainfed irrigation, and lack of access to training sessions inhibit farmers' acceptance of the idea of compost production (overall p value = 0.000). Large cultivated areas and rainfed irrigation is also associated with farmers' unwillingness to produce compost, besides high household monthly income, animal or mixed animal-plant farming, experience in compost production, and use of pesticides (overall p value = 0.000).

Perspective: regulation of pest and disease control strategies and why (many) economists are concerned.

Pests and diseases are a continuous challenge in agriculture production. A wide range of control strategies have been and will continue to be developed. New control strategies are in almost all countries around the world assessed prior to approval for use in farmers' fields. This is rightly so to avoid and even reduce negative effects for human health and the environment. Over the past decades the approval processes have become increasingly politicized resulting in an increase in the direct approval costs and the length in approval time without increasing the safety of the final product. This reduces the development of control strategies and often has negative human health and environmental effects. Possibilities exist for improvements. They include reducing approval costs and approval time by streamlining the approval process and substituting approval requirements by strengthening ex-post liability. © 2018 Society of Chemical Industry.

How low can you go? Estimating impacts of reduced pesticide use.

Recent research has suggested that a high proportion of farms can dramatically reduce pesticide applications without reducing crop yields or farm profits. Yet this research has made estimation choices that may systematically bias downwards estimates of the productivity and profitability of pesticides. Fifty years of agricultural economics research provides lessons about how to avoid pitfalls in estimating pesticide productivity. Carefully executed econometric studies have found evidence of overuse, underuse, and near-optimal use of pesticides in different cropping systems. There are now standard methods to test and correct for sources of biases (either upward or downward) in estimates of pesticide productivity. Ignoring these lessons and methods can seriously bias estimates of the potential for reducing pesticide use at little or no economic cost. © 2018 Society of Chemical Industry.

Crop Protection Discovery: Is Being the First Best?

Current crop protection chemicals span an array of chemistry classes and modes of action. Typically, within each chemistry class, there are multiple chemically distinct active ingredients competing with each other for market position. In this competition, the first product to market in a new class or mode of action may or may not have an advantage depending upon a number of parameters, including relative efficacy against the target pests, pest resistance, regulatory pressures, synthetic complexity, and marketing effectiveness. The number of companies involved in the discovery of new crop protection compounds has been declining, and patenting strategies have become more sophisticated, making it more challenging to break into an existing area of chemistry. One result is new classes of chemistry tend to be smaller, making first to market more beneficial than in the past. Additionally, the first into a market with a new class of chemistry has the opportunity to set positioning and expectations.

Official control of plant protection products in Poland: detection of illegal products.

Market presence of illegal and counterfeit pesticides is now a global problem. According to data published in 2012 by the European Crop Protection Association (ECPA), illegal products represent over 10% of the global market of plant protection products. Financial benefits are the main reason for the prevalence of this practice. Counterfeit and illegal pesticides may contain substances that may pose a threat to the environment, crops, animals, and humans, inconsistent with the label and registration dossier. In Poland, action against illegal and counterfeit plant protection products is undertaken by the Main Inspectorate of Plant Health and Seed Inspection (PIORiN), the police, the prosecution, and the pesticide producers. Results of chemical analyses carried out by the Institute of Plant Protection - National Research Institute Sosnicowice Branch, Pesticide Quality Testing Laboratory (PQTL IPP-NRI Sosnicowice Branch) indicate that a majority of illegal pesticides in Poland are detected in the group of herbicides. Products from parallel trade tend to have the most irregularities. This article describes the official quality control system of plant protection products in Poland and presents the analytical methods for testing pesticides suspected of adulteration and recent test results.

Farmers' Willingness to Pay for Health Risk Reductions of Pesticide Use in China: A Contingent Valuation Study.

This study aimed to estimate farmers' willingness to pay (WTP) for health risk reductions of pesticide use by applying the contingent valuation method (CVM) and to explore the factors that influence farmers' WTP in China. In total, 244 farmers were randomly selected and interviewed. The mean WTP was estimated to be $65.38 (0.94% of total household income) per household per year for a 5/10,000 reduction in morbidity risk. This study shows that farmers' socioeconomic and attitudinal factors that significantly affect their WTP include farmers' farming income, education, household size and risk perceptions. In particular, the results demonstrate that respondents' social trust, social reciprocity and social networks have significant impacts on their WTP. The findings of this study can provide useful insights for policy makers to design effective policies to address health problems related to pesticide use in the developing world.

Parkinsonism Signs and Symptoms in Agricultural Pesticide Handlers in Washington State.

OBJECTIVES: Examine associations between pesticide exposure and signs or symptoms of parkinsonism. METHODS: Prior to the 2014 pesticide spray season, the authors examined 38 active pesticide handlers aged 35 to 65 (median: 43.5) who participated in the State of Washington's cholinesterase monitoring program in the Yakima Valley, where cholinesterase-inhibiting insecticides are applied in fruit orchards. A movement disorder specialist assessed the workers using the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscore 3 (UPDRS3). Participants also self-reported work and medical histories, including the UPDRS activities of daily living subscore 2 (UPDRS2). The authors explored the relation between these scores and lifetime occupational pesticide exposure while accounting for age. RESULTS: All participants were Hispanic men born in Mexico who had worked in agriculture for 4 to 43 years (median: 21 years, including 11 years applying pesticides, mostly in the United States). Ten participants (26%) reported difficulty with one or more UPDRS2 activities of daily living (maximum = 2), and nine (24%) had a UPDRS3 >0 (maximum = 10). The most common symptom and sign, respectively, were excess saliva (n = 6) and action tremor (n = 5). UPDRS2 and UPDRS3 scores were unrelated to the number of years applying pesticides, but UPDRS3, especially action tremor, was positively associated with living on or by a farm. CONCLUSIONS: Symptoms and signs of parkinsonism were absent to mild in this small sample of active workers who apply cholinesterase-inhibiting insecticides in Washington State, USA. Future studies should be larger and examine older, retired workers with greater cumulative exposure to agricultural pesticides at work and home, including other types of agricultural pesticides.

Glycolipid biosurfactants: main properties and potential applications in agriculture and food industry.

Glycolipids, consisting of a carbohydrate moiety linked to fatty acids, are microbial surface active compounds produced by various microorganisms. They are characterized by high structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface, respectively. Rhamnolipids, trehalolipids, mannosylerythritol lipids and cellobiose lipids are among the most popular glycolipids. They have received much practical attention as biopesticides for controlling plant diseases and protecting stored products. As a result of their antifungal activity towards phytopathogenic fungi and larvicidal and mosquitocidal potencies, glycolipid biosurfactants permit the preservation of plants and plant crops from pest invasion. Also, as a result of their emulsifying and antibacterial activities, glycolipids have great potential as food additives and food preservatives. Furthermore, the valorization of food byproducts via the production of glycolipid biosurfactant has received much attention because it permits the bioconversion of byproducts on valuable compounds and decreases the cost of production. Generally, the use of glycolipids in many fields requires their retention from fermentation media. Accordingly, different strategies have been developed to extract and purify glycolipids. © 2016 Society of Chemical Industry.

Increasing social welfare by taxing pesticide externalities in the Indian cotton sector.

BACKGROUND: Pesticide use in the Indian cotton industry has decreased with the introduction of Bt cotton, but rates are still high in comparison with other countries. The adoption of alternative strategies, such as integrated pest management, has been slow, even though benefits are potentially high, more so if the full costs of the external effects of the technologies are taken into account. In order to estimate true societal benefits of different strategies, we compare their external costs and economic performance under external cost taxation, using a state-of-the-art partial equilibrium model of the Indian agricultural sector. RESULTS: Pesticide externalities lower social welfare in the Indian cotton sector by $US 400-2200 million, depending on the technologies employed. A full internalisation reduces producer revenues by $US 100 ha-1 if only Bt cotton is used, and by $US 30 ha-1 if IPM is another option. Consumers do not start to lose surplus until 20-70% are internalised, and losses are smaller if all technologies are available. CONCLUSION: External pesticide costs can be internalised partially without substantially affecting consumer surplus while still increasing social welfare, but producers need to have access to and the knowledge to employ all available cotton production technologies to minimise losses. © 2016 Society of Chemical Industry.

Aerial Prefeeding Followed by Ground Based Toxic Baiting for More Efficient and Acceptable Poisoning of Invasive Small Mammalian Pests.

Introduced brushtail possums (Trichosurus vulpecula) and rat species (Rattus spp.) are major vertebrate pests in New Zealand, with impacts on conservation and agriculture being managed largely through poisoning operations. Aerial distribution of baits containing sodium fluoroacetate (1080) has been refined to maximise cost effectiveness and minimise environmental impact, but this method is strongly opposed by some as it is perceived as being indiscriminate. Although ground based control enables precise placement of baits, operations are often more than twice as costly as aerial control, mainly due to the high labour costs. We investigated a new approach to ground based control that combined aerial distribution of non-toxic 'prefeed' baits followed by sparse distribution of toxic baits at regular intervals along the GPS tracked prefeeding flight paths. This approach was tested in two field trials in which both 1080 baits and cholecalciferol baits were used in separate areas. Effectiveness of the approach, assessed primarily using 'chewcards', was compared with that of scheduled aerial 1080 operations that were conducted in outlying areas of both trials. Contractors carrying out ground based control were able to follow the GPS tracks of aerial prefeeding flight lines very accurately, and with 1080 baits achieved very high levels of kill of possums and rats similar to those achieved by aerial 1080 baiting. Cholecalciferol was less effective in the first trial, but by doubling the amount of cholecalciferol bait used in the second trial, few possums or rats survived. By measuring the time taken to complete ground baiting from GPS tracks, we predicted that the method (using 1080 baits) would be similarly cost effective to aerial 1080 operations for controlling possums and rats, and considerably less expensive than typical current costs of ground based control. The main limitations to the use of the method will be access to, and size of, the operational site, along with topography and vegetation density.