Development and application of simple test kits for pesticide residues in plant-derived foods

• Central Food Technological Research Institute, India

In India, agriculture is the most important sector of the economy, accounting for over 30% of gross domestic product. The use of chemicals (mainly insecticides) to control pests, poses a regular health risk. India is the largest producer and user of pesticides in Asia and continues high-level consumption of many active ingredients which have been banned elsewhere. A comprehensive and reliable residue monitoring program is needed to complement pest and postharvest management strategies to ensure that levels of residues in food remain acceptably low.

Major techniques currently used for monitoring chemical residues are gas chromatography (GC) and high performance liquid chromatography (HPLC) but these methods require extremely expensive equipment and highly trained technicians, and are rarely available in developing countries such as India. Indian scientists have been active in research to develop simple spectroscopic tests, but the sensitivity of the assay is low and scientists need more laboratory equipment.

The main objective of the project is to develop tests for pesticides that have given rise to significant residue problems in India or Australia. Antibody tests will be developed for individual pesticides such as DDT and its metabolites, hexachlorocyclohexane (HCH, and its gamma isomer), endosulfan and dimethoate. A range of broad-specificity tests will be developed for analysis of groups of pesticides such as organophosphates, carbamates, organochlorines and fungicides. Test procedures already developed by CSIRO will be modified for use on fruit, vegetables, tea, oilseeds and other fatty commodities. An appropriate kit format for drinking water will also be included.

The CSIRO Division of Plant Industry have been developing new tests for pesticide residues in cereals and cereal-based foods, using specific antibodies and pesticide-enzyme complexes. Test kits have been produced for either laboratory or field use. The tests kits are for personnel with minimal training and are more sensitive than conventional methods. Successful trials were carried out in Australia and overseas in 1992 and the first kits became routinely available in December 1992.

Development of specific immunoassays and broad receptor assays and production of prototype kits for use in India and Australia will be undertaken by scientists at the CSIRO Division of Plant Industry, Canberra. Existing expertise in the CSIRO in developing these assays means the chance of success is very high. Researchers in both Australia and at the CFTRI, India will collaborate in the development of suitable extraction methods for residues from water and various foods. CFTRI researchers will perform most of the food collection, GC analysis and assessment of the new assays with a wide range of foods. A member of the research team at CFTRI will spend five months at CSIRO to gain experience in the each of the test development stages.