In this study the toxicity of antimalarial drug chloroquine (CQ) on certain enzymological (GOT, GPT and LDH) and histopathological alterations (Gill, liver and kidney) of a freshwater fish Cyprinus carpio was studied after acute (96 h) and sublethal (35 days) exposure. The median lethal concentration (96 h) of CQ was 31.62 mg/ml. During acute treatment (CQ at 31.62 mg/ml) the treated fish groups showed a significant increase in GOT and GPT activities in blood plasma; whereas LDH activity was decreased when compare to control groups. To analyse the effects of drug at the lowest concentration, the fish were exposed to 3.16 mg/ml (1/10th of 96 h LC50 value) for 96 h. In sublethal treatment (3.16 mg/ml) GOT activity increased up to 14th day and decreased during the rest of the exposure period (21, 28 and 35th day). A biphasic response in GPT activity was observed. LDH activity was found to be increased throughout the study period (35 days) compare to control groups. The alterations in enzyme activities in blood plasma were found to be significant at p < 0.05 (DMRT). Many histopathological changes in vital organs such as gill, liver and kidney of fish were observed in CQ treated group (acute and sub-lethal) compare to normal group. The alterations in the enzymological and histopathological study in the present investigation indicate that the drug CQ has toxic effects on non-target organisms. We conclude that the alterations in enzymological parameters and histopathological changes can be used as biomarker to assess the health of the aquatic organism/environment. Further data on molecular studies are needed to define the mode of action and toxicity of these emerging pollutants.

BackgroundUse of pesticides in agricultural fields has a series of toxicological and environmental problems. Methyl parathion (MP), an organophosphorus (OP) insecticide is a widely used pesticide and is highly toxic to non-target organisms. Fish has been used as indicator species for monitoring of pollution in the aquatic environment. Catla catla an Indian major carp is an edible fish and is highly sensitive to slight stress. Recently, fish biomarkers are widely used to determine the internal and external health status caused by chemicals.ResultsC. catla were exposed to acute (0.09ppm) and sublethal (0.009ppm) concentrations of MP to determine the alterations in antioxidant and metabolic enzyme activities in blood plasma and tissues (gill and liver). Intoxication with MP resulted in induction of oxidative stress which implies that fish utilizes enzymatic mechanisms to tolerate the effects caused by generated ROS due to MP accumulation. Significant alterations in GOT and GPT activity in plasma and tissues during acute as well as sublethal exposure might have resulted from the organal damage. The significant increase of LDH activity indicates severe cellular damage in organ/tissues of MP treated fish.ConclusionThe results of the present investigation suggest that gill is the most sensitive organ to MP toxicity. The alterations of the enzymatic parameters can be effectively used as potential biomarkers for monitoring of the organophosphorus pesticides in aquatic environment. Further, MP should be used with caution in order to protect natural waters and aquatic organisms

In this study, the chronic toxicity effects of iron oxide (Fe2O3) nanoparticles (NPs) (500mgl−l) on certain hematological, ionoregulatory and gill Na+/K+ ATPase activity of an Indian major carp, Labeo rohita were estimated for a period of 25days under static bioassay. A significant increase in hemoglobin (Hb) content, red blood cell (RBC) count and hematocrit (Ht) value was noticed throughout the study period when compared to control groups. In contrast, mean cellular volume (MCV), mean cellular hemoglobin (MCH) (except on 5th day) and mean cellular hemoglobin concentration (MCHC) levels and white blood cell (WBC) counts were found to be decreased during the above study period. Fe2O3 NPs also caused alterations in iono regulation resulting in hyponatremia (Na+), hypochloremia (Cl−) (except on 5th day) and hypokalemia (K+) (except up to 15th day). A biphasic trend in gill Na+/K+-ATPase activity was noticed during the above treatment period. Our results demonstrate that high Fe2O3 NP concentrations in the aquatic environment may have adverse physiological effects on fish. These data may be useful to assess the environmental risk posed by NPs. However the toxicity of various sizes of the nanoparticle could be evaluated using different aquatic organisms