TOXICOLOGICAL STUDY of ORGANOTHIO PHOSPHATES

Pesticides have contributed impressively to our present-day agricultural productivity, but at the same time they are at the centre of serious concerns about safety, health, and the environment. Pesticide poisoning from occupational, accidental and intentional exposure is a major developing world health problem. Millions of people are exposed to danger by hazardous occupational practices and unsafe storage. However, it is the deliberate self poisoning that causes the great majority of the deaths, particularly in Asia (Eddleston, 2000). Pesticide poisoning is a significant concern in India. OPPs cause most self-poisoning death in southern and central India (Srinivas Rao et al., 2005). There are more than 100 different OPPs that are extensively employed over the world for their broad insecticidal spectrum and short persistence in the environment. A wide range of OPPs, especially thiophosphorus OP insecticides were used in India and in most instances of poisoning, the identity of the OP agent involved was not known with certainty, resulting in deficiencies or delays in management. 



Thus, a rapid identification of causal pesticide would provide very useful information to clinicians for making treatment decisions in emergencies, which is also important in forensic cases (Musshoff et al., 2002). Due to numerous applications of triphosphates on the one hand and difficulties with their analysis on the other hand, it is crucial to improve their determination methods in terms of selectivity and sensitivity. Overall, OPPs account for an increasing number of human intoxication cases, which are not always well-diagnosed or documented. 



Furthermore, the acute lethal doses of many pesticides in humans remain to be established. Moreover, although several fatalities due to OPPs have been previously published, little quantitative toxicological data have been found in the literature. Usually, these compounds were detected using a general extraction and screening procedure, but these methods were not developed or optimized to selectively extract and detect the exact causal OP compound. In some medico-legal jurisdictions, the courts require unambiguous identification of the parent compound, which poses a problem for the toxicologist, and much effort has been expended on developing suitable analytical approaches. 



The broad aims of this study were to characterize the toxicity of selected OPPs and to access the feasibility of determining residues of intact OPPs in forensic matrices, especially in biological specimens obtained in acute fatal cases. The OPPs selected for this study are chlorpyrifos (CPF), quinalphos (QLP) and triazophos (TZP). These diethyl thiophosphates are those that are commonly ingested OPPs with numerous reported acute fatal cases in forensic toxicology laboratory.