Advances in Biological Chemistry, 2015, 5, 225-233 Published Online October 2015 in SciRes. http://www.scirp.org/journal/abc http://dx.doi.org/10.4236/abc.2015.56019 How to cite this paper: Basopo, N. and Ngabaza, T. (2015) Toxicological Effects of Chlorpyrifos and Lead on the Aquatic Snail Helisoma duryi. Advances in Biological Chemistry, 5, 225-233. http://dx.doi.org/10.4236/abc.2015.56019 Toxicological Effects of Chlorpyrifos and Lead on the Aquatic Snail Helisoma duryi Norah Basopo * , Thamsanqa Ngabaza Department of Applied Biology and Biochemistry, National University of Science and Technology, Bulawayo, Zimbabwe Email: * norah.basopo@nust.ac.zw Received 1 September 2015; accepted 18 October 2015; published 21 October 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Aquatic reservoirs remain the ultimate sink of chemical pollutants emanating from anthropogenic activities such as agriculture, mining and industry. Freshwater biota undoubtedly is at risk from the adverse effects of these water pollutants and there is therefore, a need to monitor effects of these chemical pollutants in order to safeguard the health of aquatic biota. We investigated the oxidative stress effects of chlorpyrifos and lead on the freshwater snail Helisoma duryi to assess the potential of using this enzyme system as a biondicator of exposure to environmental pollu- tants. Groups of snails were exposed to 5 ppb lead acetate and 25 ppb chlorpyrifos for 7 days after which half of the snails were sacrificed and the other half were allowed to recover in clean water and sacrificed after another 7 days. Post mitochondrial fractions were used to measure the activi- ties of the following antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and diphosphotriphosphodiaphorase. Both pollutants enhanced the ac- tivities of all the antioxidant enzymes suggesting a defensive mechanism by the snail to combat the oxidative stress due to the organophosphate chlopryrifos and metal pollutant lead. There was a significant recovery of the antioxidant defense system of the snails allowed to recover in clean water shown by the reduced alteration of the antioxidant enzyme activities of the snails allowed to recover for 7 days. This suggests the need to minimize exposure of aquatic biota to chemical pol- lutants and remediate the polluted water reservoirs in order to safeguard the health of aquatic life. Keywords Pollutants, Snails, Oxidative-Stress, Organophosphates, Metals * Corresponding author.