ISSN 2320-5407 International Journal of Advanced Research (2016), Volume 4, Issue 2, 926-931 926 Journal homepage: http://www.journalijar.com INTERNATIONAL JOURNAL OF ADVANCED RESEARCH RESEARCH ARTICLE TOXIC INFLUENCE OF DICOFOL ON THYROID GLAND IN FEMALE PUBERTAL RATS. K.V Kavitha , Nimmi Francis, E Jayadevi Variyar. Department of Biotechnology and Microbiology, Kannur University, Thalassery Campus, Palayad P.O; Kannur, Kerala, 670661, India. Manuscript Info Abstract Manuscript History: Received: 14 December 2015 Final Accepted: 19 January 2016 Published Online: February 2016 Key words: Dicofol, Thyroid, Pubertal, histology. *Corresponding Author E Jayadevi Variyar Evidences for thyroid disruption due to organochlorine exposure are increasing. The present study investigated the toxic influence of dicofol, an organochlorine pesticide on thyroid gland in female pubertal rats. The experiments were carried out in three equal groups of animals from PND 22 to 60 day .Two groups received dicofol orally at 5.87(1/100 LD50) and 19.27(1/30 LD50) mg/kg body wt. The third group was kept as control. Daily body weight was checked during the exposure period. Upon completion of exposure blood samples were taken for thyroid hormone estimation and thyroid gland was dissected, weight determined and processed for histopathological studies. There was a dose dependent significant decrease in the body weight gain in dicofol treated groups when compared with control. A significant increase in the thyroid weight was observed in high dose treated group. Histological studies of thyroid revealed degenerative changes in a dose dependent manner. The serum T3,T4 and TSH levels also indicate such a hypoactive thyroid, similar with histological results. These data suggest that exposure to dicofol may cause a hypofunctioning of thyroid gland. Copy Right, IJAR, 2016,. All rights reserved. Introduction:- Pesticides are a group of chemicals made for the purpose of killing or deterring pest. Irrational use of pesticides has led to many clinical symptoms in humans, animals and led to the deterioration of environment. Problems associated with pesticide hazard to man and environment are not confined to developing nations, but extended to developed countries as well (Nuckols JR et al.,2007). Europe is now the largest pesticide consumer in the world, followed by Asia. China is the largest pesticide producer and exporter in the world (WenJun Zhang, 2011). Most of the pesticides worldwide are used on fruit and vegetable crops. Among the pesticides organochlorine pesticides are a major class of commonly used pesticides. They degrade relatively slowly in the environment and being lipophilic accumulates in the fatty tissues of animals. Thus they remain in the environment and food web long after application (Swackhamer D, 1988). Chronic exposure to low concentrations of organochlorine pesticides over a long period may eventually lead to the accumulation of these toxic chemicals in the body (Penelope J.E. Quintana et al., 2004). In recent years, the presences of toxic pesticides have been reported in various biological materials such as milk, blood and fatty tissues from animals and humans (John PJ et al., 2001, Minakshi Rathore et al., 2002, FujiiY etal. 2011). According to the Center for Disease Control and Prevention(CDC), presence of a low percentage of organochlorine pesticides have been detected in tissues of most humans and animals (NCEH.2005).This causes great problems in the body including the disturbances of hormones controlling the metabolism. Food is considered to be the main source of organochlorine pesticides in the human body (Morgan DP,1974). Many organochlorine pesticides are endocrine disrupting chemicals, leading to toxic effects on the body’s hormonal systems (Lemaire G et al., 2004). Dicofol is an organochlorine pesticide currently registered for use on a variety of food crops in India and many other countries. It is structurally similar to DDT. It is a non systemic miticide (a chemical that kills mites) with several