Pesticides Surveillance on Surface Waters: Developing a Method for Watersheds Prioritization

The occurrence of pesticides in drinking water is a matter of growing concern in several parts of the world, mainly in developing countries, due to the possible adverse effects on human health and the environment. Pesticides applied in the agriculture, important source of contamination, can persist for several years in soil, be retained in agricultural products, be dispersed by the wind or reach the surface and ground waters (Tomita & Beyruth, 2003). Traces of pesticides can be found, both in soil and water sources, depending on their physical and chemical properties, their application and dose patterns, as well as the local environmental characteristics. In Brazil, pesticide monitoring in surface water, both by water supply operators and health authorities, is still rare and insufficient for assessing health risks, often not accomplishing the legal issues regarding the quality control of raw waters (Brazil, 2004b). Inclusion of the whole set of these parameters in monitoring plans is unusual, mainly due to high costs of the analyses and to necessity of specialized manpower. There is also a lack of data on pesticides use in agriculture, in the several Brazilian regions, as well as of studies that associate their use with presence in water and with health risks. Additionally, low potential of pesticides removal in most of the Brazilian water treatment plants completes the picture of lack of reliable information on health risks associated with pesticides exposure by water ingestion. The lack of data and of financial and material resources to comprehensive pesticide surveillance suggests tracing other alternatives to the evaluation of potentiality of pesticides occurrence in surface water. Thus, the aim of this chapter is to discuss a method for prioritization of surveillance actions of pesticides in surface waters, through multicriteria analysis. In the chapter, firstly we discuss concepts related to the subject. Secondly, the structure of the method is presented and, thirdly, we describe an application in Rio Grande basin, Minas Gerais, Brazil. Finally, we draw some conclusions on the study.