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Cycle 6 (2017 Deadline)

Mapping of pesticide residue and oocysts on vegetable and fruits using low-cost field based assays

PI: Basant Giri,, Kathmandu Institute of Applied Sciences
U.S. Partner: Toni Barstis, Saint Mary's College, Notre Dame, Indiana
Project Dates: December 2017 - November 2019

Project Overview:

Contamination of vegetables and fruits by pesticides and endoparasites is a major public health concern in developing countries, including Nepal. Pesticides are widely used worldwide to protect crops from pests, but their excessive and unmanaged use is harmful to humans and the ecosystem. Pesticides are well-known toxins that cause acute and delayed health effects, including disruption of the central and peripheral nervous systems and cancer. Similarly, according to the World Health Organization (WHO), about 8% of total deaths reported in Southeast Asia are caused by diarrhea. In Nepal, several instances of diarrheal outbreaks are reported every year. Human exposure to pesticides and parasites is due to contaminated food and water. Concerns over food pollution are rising in Nepal, but science-based understanding of the level of pollution is limited, due in part to the unavailability of reliable, economical, easy-to-use, and rapid field test methods to be used as important early warning tools for consumers. Conventional methods for determining pesticide residues on food involve sophisticated, time-consuming, expensive chromatographic methods that require advanced lab facilities and skilled operators. Similarly, endoparasite oocysts in food products are identified using expensive, high resolution optical microscopes, immunofluorescence-based microscopy, and polymerase chain reaction techniques that are not suitable for field screening of samples in developing countries. This project aims to develop (1) a paper-based pesticide residue assay and (2) smartphone-based oocyst assay methods. Both of these high throughput, low-cost, easy methods will be first developed and validated in the laboratory and later tested with vegetable samples at various locations across Nepal. It will be the first large-scale field testing of these methods with real samples. Other activities on the project will include providing training to students and government technicians, organizing workshops for concerned stakeholders, creating online map with field results, and disseminating information. Bringing reliable assay methods for pesticide residue and oocysts for public use with the possibility of commercialization will be the major output of the project. The USG-supported partner will provide technical advice and training for both the lab development and field testing components.

In addition, the team will involve undergraduate students from the Tri-Chandra Multiple Campus, Tribhuvan University. They will learn to use the newly developed assay methods and go into the field to test food pollution levels. In addition, two Master’s students from the Central Department of Environmental Science, Tribhuvan University, will be given the opportunity to carry out their thesis work in the framework of this project. The PI and his colleagues will share their field screening findings and involve the Plant Protection Directorate (PPD) of the Government of Nepal. PPD technicians will be trained in the new methods and be given some of the assay tools. Two workshops and one symposium will also be organized to share the results of the project.

Summary of Recent Events

In this project, the PI Dr. Basant and his team aim to develop two types of devices and methods. The first one is a paper-based analytical device to determine the pesticide residue in vegetables and fruits. The second one is a smartphone-based microscope that will count the (oo)cysts in vegetable and fruits samples. After developing these two techniques, the project also aims to test and validate the methods using field-collected samples.

In this reporting period, the PEER team obtained three important pieces of equipment: a fluorescence microscope, a digital balance, and a water purification system. The smartphone microscopic method has been optimized with several parameters such as lens size, light source, type of stain, and so on. They have also completed spike recovery experiments using drinking water, river water, and five types of vegetable samples. Currently, they are testing contamination of river water using this technology. Since they now have a fluorescence microscope, they will also compare the results from the smartphone microscopic method with the fluorescence microscopic method in the next quarter. Similarly, a beta version of the smartphone application for data reading and reporting of pesticide PAD is ready.

The PI and his team are currently assessing the accuracy of the app and looking at it from a user perspective. They continued to study the improvement in the storage time of the enzyme and enzyme substrate that are used for pesticide detection on paper at ambient condition. They have been able to retain more than 70% of enzyme activity for four months and more than 88% of substrate activity for 40 days. In the next reporting period, they will finalize the smartphone application and paper device. They will also make a sample collection plan, visit collection sites, and organize a training program for undergraduate students on paper device.

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