Concomitant exposure to arsenic and organophosphates on tissue oxidative stress in rats

Increased use of organophosphates (OPs) and ever increasing arsenic levels in drinking water and their co-existence in the environment could be potentially hazardous. The present study examines the effects of dichlorvos (DDVP) or monocrotophos (MCP) and sodium meta arsenite, individually or in combination for 16 weeks on variables indicative of hematological and tissue oxidative injury in rats. Co-exposure to DDVP, MCP or arsenic produced significant inhibition of brain and serum AChE levels suggesting synergism. Significant increase in hepatic reactive oxygen species and brain thiobarbituric acid reactive substances was observed in arsenic and OPs exposed animals. Co-exposure to arsenic and OPs exhibited synergism in case of ROS while antagonism was noted in case of TBARS. Serum transaminases increased significantly on exposure to OPs and arsenic suggesting liver injury which was less pronounced in case of co-exposure to DDVP and arsenic. WBC counts too showed less pronounced increase on co-exposure to arsenic with OPs compared to all other exposure. Blood arsenic level decreased on co-exposure to arsenic with OPs. The present study points to some interesting observations regarding interaction between arsenic and organophosphates. While, exposure to arsenic, DDVP and MCP lead to significant oxidative stress, their co-exposure not necessarily produce synergistic effects.