Degradation of pesticides

Abstract

The ever-growing human population, which is expected to be 9.1 billion by 2050 (UN 2005), will require more agricultural production, especially in tropical regions. Increasing agricultural production in these regions relies on the use of agrochemicals, as shown by the growth of agrochemical market by approximately 4.5% annually. On the one hand, use of agrochemicals helps in meeting with the dietary needs of the ever-increasing world population, but on the other hand, many agrochemicals used in agricultural activities contaminate soil, air, and water resources. Therefore, it becomes imperative to identify and quantify the chemical and biological processes that control the behavior of organic chemicals in the environment to improve pesticidal management for minimizing contamination of our natural resources and remediating contaminated environment. To an estimate, we have an annual production of approximately 106 tons of active ingredients worldwide. Assuming a total arable land area of 13.8 × 106 km2 on earth, though unrealistic, the even distribution of pesticides would amount to about 0.7 kg/ha year. So, much use of organic chemicals by all sectors of the economy is affecting human health and environment as the result of soil, air, and water contamination. These effects may range from growth retardation to physiological or behavioral deficiencies, which substantially affect the most sensitive individuals or species (Atterby et al. 2002; Bollag and Liu 1990). Subsequently, it may lead to population shift resulting in ecological changes. Pesticides, when used in agriculture, are likely to enter various compartments of the environment. They may undergo leaching by water, volatilization into atmosphere, or sorption to various surfaces. When introduced into the environment, the fate of pesticides is influenced by three major processes: transfer (sorption), transport (runoff, leaching, and volatilization), and transformation (chemical degradation (hydrolysis and photolysis) and microbial degradation).