Environmental Fate and Analysis of Insecticidal Fumigant Residues in Stored Grain and Grain-Based Products

[摘要] The work described in this thesis is principally concerned with the environmental fate and analysis of halogenated hydrocarbons commonly used as insecticidal fumigants on stored grains and their by-products. The fumigation of stored products with these volatile compounds, which has been a common practice for centuries, is designed to destroy insects infesting the food and the storage area. The fumigated grains are normally used as food for human and animal consumption. The chemicals applied on them are highly toxic and are environmental hazards. There has been consistent evidence that some of these chemicals remain associated with foodstuffs as residues for a long period after treatment and therefore become a potential risk to human beings and the environment as a whole. Environmental pollution, an increasing threat to the world, is often not directly perceptible and therefore its protection has become a major goal all over the world. In attempting to predict the fate of fumigants in cereal grains, a full understanding of how the many parameters may influence the physical or chemical interaction of fumigants with grains or other food commodities and the ability to detect and determine the residues remaining in such food is essential to understanding their impact upon the environment. The effective use of these pesticides and the control of their contamination of the food supply and the environment, depends heavily on the ability to detect, identify and quantify them, often in very low concentrations. Analytical methods have been developed for the detection of fumigants as residues on fumigated food products or in the environment. The work carried out here is basically a description of an attempt to meet the main objectives of the research project discussed in Chapter One, namely; 1) critical literature review on modern fumigants and methods of fumigation, 2) environmental fate and reaction of these fumigants with the constituents of foodstuffs, and 3) development of a method or methods for fumigant residues or multiresidue analysis. Chapter Two describes a comprehensive review of the existing literature pertaining to important fumigants and their method fo application with special reference to maize and wheat grains and their by-products. The study which was carried out during the first part of the research, revealed that only about six insecticidal fumigants are currently in use largely in tropical countries. Environmental fate discussed in Chapter Three illustrated that the fumigants used for fumigation in storage are not only a public health hazard to those directly involved in fumigation or other related occupations but also those beyond the fumigation and storage premises. These chemicals have been detected in the air, water and soil especially around the fumigation area and therefore a great need for their monitoring and detection in the environment. Chapter Four deals exclusively with developments of methods that are specifically suitable for single fumigant residues. Three analytical methods with high precision and good overall recoveries were developed which allowed the determination of such a volatile fumigant as methyl bromide in very low concentrations. With the help of other improved parameters such as the electron capture detector, the capillary column and the tenax adsorbent trap, efficient and sensitive detection with good reproducibility and high recoveries was observed (Chapter Five). Chapter Six describes the advantages and disadvantages of fumigant residues methodology and evaluation assessment and compares its effectiveness with other available methods. The underlying fact revealed that a more broad and integrated method of assessment which utilises all effective methods is advisable. Finally, Chapter Seven concludes the findings, with recommendations for further vigilance and monitoring of the fumigant residues in the food supply and the environment. This suggests that, for any meaningful reduction in the risk from these chemicals and to check that internationally recommended maximum residue levels are fully adhered to, determination of fumigant residues is essential before any treated commodity is consumed by humans or animals.(Abstract shortened by ProQuest.).

[发布机构] University:University of Glasgow

[关键词] Agricultural engineering, Organic chemistry