Reducing human health and environmental risks from pesticide use: Integrating decision-making with spatially-explicit risk assessment models. The case of Vereda La Hoya, Colombia
The livelihood of small farmers in developing countries depends on their ability to employ ecologically and economically sound production methods. While properly applied pesticides reduce yield losses up to 40% and improve product quality, their misuse may cause serious human health and environmental problems. Farmers and farm workers in developing countries are directly exposed to pesticides during preparation of the pesticide mixture, pesticide application, and washing of the pesticide receptacles and the clothes used for application. Farmers might be indirectly exposed through inhalation during application; and farmers’ family members through contact with contaminated plants, clothes and residues brought into the house. In Colombia, for people living in mountainous regions, agricultural production is one the most important sources of income. It accounts for the 21% of the Gross National Product and 40 % of the labor force. Regarding pesticide use, Colombia has the 4th highest consumption and use of fungicides in the world and the 2nd in South America after Brazil. Results from the surveillance program for pesticides that affect the neurological system, e.g., organophosphates and carbamates, showed 21,450 individuals with high-risk exposure to these chemicals. Since the 1970s, the Colombian government has been developing a regulation program for agrochemical production and applications and has issued several administrative rules and codes. Despite the existing regulatory restrictions, the current use of pesticides in Colombia has not decreased and human health and environmental problems remain an issue of major concern.
A number of important aspects must be considered in research efforts aimed at reducing environmental risks originating from the misuse of pesticides. On one hand, there is a considerable need to adapt and develop risk assessment models applicable within the defined conditions of developing countries (low amount of resources, low data availability). On the other, there is a specific need to learn more about the farmers’ perceptions of the potential risks, as well as the relevance of parameters such as traditions, and cultural values for farmers’ behavior and to integrate the findings into the development of educational programs.
The selected study area Vereda la Hoya is located in the rural part of Tunja, the capital of the Departamento de Boyacá in Colombia. It is located in the eastern chain of the Andes at an altitude of 2800 m above sea level. Vereda la Hoya has an area of 840 ha and a population of about 747 inhabitants. Due to its altitude and geographical location, the average temperature in the region is 13°C, with an average night-time temperature of 5°C and an average day-time temperature of 20°C. It is a relatively dry region with an average precipitation of 600 mm per year in two wet seasons. The main source of income is farming. Farmers cultivate minifundios, i.e., their property has an average size of 3 ha. Land use in the area consists of (i) forest: 40%, (ii) animal husbandry: 35%; and (iii) agriculture: 25%. The main agricultural products grown are potatoes (85%) and carrots (9%). Given the high soil fertility and the climatic conditions, farmers typically cultivate two cycles of potatoes a year, followed by either one or two carrot crops or one bean crop, and finishing with two to three years of pasture. Potato crops in this region are vulnerable to three major pests: the soil-dwelling larvae of the Andean weevil (Premnotrypes vorax, “Gusano blanco”), the late blight fungus (Phytophthora infestans, “Gota”) and the Guatemalan potato moth (Tecia solanivora, “Polilla guatemalteca”).
The project aimed to develop a model for deriving and assessing strategies for reducing human health and environmental risks from pesticide use.
In pursuing these aims, the proposed research integrates farmers’ decision-making with a spatially explicit dynamic risk assessment to address the following questions:
1. How do farmers perceive the risk associated with pesticide application; how does their perception differ from that of experts and scientific models?
2. How do parameters (e.g. assets, such as education, norms, and culture) structure and determine farmers’ production choices?
3. What is farmers’ exposure to pesticides and what is the spatial distribution of the environmental risks from pesticide application?
4. What is the potential effect of farmers’ scenarios and policy measures on farmers’ behavior and on the environment?
The research was divided into the modules (i) farmers’ perception and decisionmaking, (ii) spatially explicit dynamic risk assessment and (iii) simulation and assessment of scenarios and mitigation strategies. The project adopted several methods, including the Structured Mental Model Approach, a System Analysis Workshop, a survey, statistical and system dynamics modelling, and spatially-explicit pestcide fate modelling. The final simulation model is composed of farmers’ decision-making model and the spatially explicit risk assessment model.
The project was led by Prof. Dr. Claudia R. Binder in Switzerland (University of Zurich) and Prof. Ing. Jaime Diaz in Colombia (Universidad de Boyacá). The core research team consisted of Giuseppe Feola; Dr. Glenda Garcia Santos; Dr. Stefan Leyk; Regina Schöll and Jing Yang. During this project several researchers and students in Switzerland and Colombia were involved
Swiss National Science Foundation.
Binder, C.R., García-Santos, G., Andreoli, R., Diaz, J., Feola, G., Wittensöldner, M., Yang, J., 2016. Simulating human and environmental exposure from hand-held knapsack pesticide application: Be-WetSpa-Pest, an integrative, spatially explicit modeling approach. Journal of Agricultural and Food Chemistry 64, 3999−4008. [Open access here]
García-Santos, G., Feola, G., Nuyttens, D., Diaz, J. ,2016. Drift from the use of handheld knapsack pesticide sprayers in Boyacá (Colombian Andes). Journal of Agricultural and Food Chemistry 64, 3990−3998. [Open access here]
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Feola, G., Schoell, R., Binder, C.R., 2010. Identifying barriers and opportunities for transitions towards more sustainable agriculture through system analysis. The case of Vereda La Hoya,Colombia. In: Darnhofer, I., Grötzer, M. (Eds.), Building sustainable rural futures: The added value of systems approaches in times of change and uncertainty: proceedings. Vienna, A, University of Natural Resources and Applied Life Sciences, 1873-1883. [Also available here]