Chronic Exposure to Pesticides- Neurological, Neurobehavioral and Molecular Targets of Neurotoxicity

There is an increasing concern regarding the widespread use of pesticides and their potential impacts on public health. Pesticides differ from other chemical substances because they are toxic chemicals deliberately spread into the environment with the aim of controlling undesired living species. Since their toxicity may not be completely specific for the target organisms, their use may pose a risk to human health. Pesticide poisoning remains a serious public health problem worldwide. More than 5 billion pounds of pesticides are used annually worldwide, with about 25% being used in the United States (US Environmental Protection Agency 2001, 2002). Pesticide exposure occurs during their application, via their drainage into water supplies, and through the consumption of food. According to the World Health Organization’s estimate, 3 million cases of pesticide poisoning occur every year, resulting in more than 250,000 deaths. This number also accounts for a substantial fraction of the almost 900,000 people worldwide who die by suicide every year. Organo-phosphorus pesticides (OPs) are currently the most commonly utilized pesticides in the world, consisting of nearly 40 different chemical members registered by the US-EPA (www.epa.gov). About 73 million pounds of OP pesticides were used in the United States above in 2001 (70% of all insecticides; Kiely et al.,2004). Pesticide poisonings are relatively common in countries such as Sri Lanka, Venezuela, Indonesia, South Africa, and Brazil. Among numerous pesticides that can result in death, organophosphate insecticides are the most common culprit agents because of their high toxicity. In developing countries, in which the use of OP compounds is particularly widespread because the hot climatic conditions, the number of deaths may be high. There is an increasing concern regarding the widespread use of pesticides and their potential impacts on public health. In the United States, a mixture of pesticide residues are detected in blood and/or urine of nearly all persons sampled (Barr et al., 2005). During the 1990s some 2.5–5.0 million agricultural workers were exposed to OPs, which are used as insecticides around the world (Abou-Donia, 2003; Das et al., 2001; Farahat et al., 2010; London et al., 1997). Although OPs are increasingly restricted for use in the US (EPA, 2002), many of the pesticides that are no longer available in the US and other developed countries are still being produced and used in agricultural or urban applications in developing countries.