27 Pesticides in the Environment: Impacts and Their Biodegradation as a Strategy for Residues Treatment Ma. Laura Ortiz-Hernández, Enrique Sánchez-Salinas, Angeluz Olvera-Velona and Jorge Luis Folch-Mallol Universidad Autónoma del Estado de Morelos México 1. Introduction A vast number of pollutants and waste materials including heavy metals are disposed into the environment per annum. Approximately 6 x 10 6 chemical compounds have been synthesized, with 1,000 new chemicals being synthesized annually. Almost 60,000 to 95,000 chemicals are in commercial use. According to Third World Network reports, more than one billion pounds (450 million kilograms) of toxins are released globally in air and water. The contaminants causing ecological problems leading to imbalance in nature is of global concern. The environmentalists around the world are trying to overcome this by several means. However, although they are raising their voices at international platforms regarding the depletion of natural resources; little attention is given to their words and many substances are still used without caring of the adverse consequences (Shukla et al., 2010). Among these chemicals we can find pesticides, which are defined as any substance or mixture of substances which are used to control destructive pests such as insects, plant disease organisms and weeds, including many other living organisms such as nematodes, arthropods other than insects, and vertebrates that endanger our food supply, health, or comfort. In particular, the term pesticide refers to chemical substances that alter biological processes of living organisms deemed to be pests, whether these are insects, mould or fungi, weeds or noxious plants. Pesticides are widely used in most areas of crop production to minimize infestations by pests and thus protect crops from potential yield losses and reduction of product quality (Damalas, 2009). These pests potentially cause damage or interfere in any other way in the production, elaboration, storage, transport, or commercialization of food, agricultural products and wood products or animal food. Pesticides may be given to animals to prevent insects, arachnids or other plagues in or over their bodies (FAO, 2002). Certainly, pesticides have improved longevity and quality of life, chiefly in the area of public health. Insect control programs have saved millions of lives by combating diseases such as malaria, yellow fever and typhus. In addition, the use of pesticides constitutes an important aspect of modern agriculture, as they are absolutely necessary for economical pest management (Gouma, 2009). The most promising opportunity for maximizing benefits and minimizing risks is to invest time, money, and effort into developing a diverse toolbox of