Search

Organophosphates (OPs) and synthetic pyrethroids (SPs) are the most popular broad spectrum pesticides, used in agriculture as they have a strong pesticidal activity while also being biodegradable in the environment. The present study aimed to demonstrate the effects of these pesticides on the Acetylcholinesterase (AChE) activity in brain, gills and body muscles of Oreochromis niloticus - an important enzyme for the assessment and biomonitoring pollution caused by neurotoxins in the environment. The fish were exposed for 24 and 48 h to the LC 0 concentrations of the malathion (1.425 mg/L), the chlorpyrifos (0.125 mg/L) and the λ-cyhalothrin (0.0039 mg/L), respectively. The activity of the AChE was significantly increased ( p  < 0.05) at 24 h and decreased at 48 h (except for the chlorpyrifos-treated brain and gills while tissues had shown no activity at 48 h's exposure) in all pesticides-treated tissues. The maximum increase in the activity and inhibition in the AChE activity were recorded as +92% and -52% in the chlorpyrifos and the lambda-cyhalothrin exposed brain tissues, respectively. Thus, the alterations in the AChE activities indicated that the applied pesticides are highly neurotoxic to fish and the enzyme (AChE) could be used as a useful biomarker for estimation of water pollution.

Organophosphates and synthetic pyrethroid pesticides are used in residential areas and agriculture, discharge into environment, may cause unpredictable toxicity to non-targeted aquatic organisms. The current study aims to assess the effect of these pesticides on the transaminases, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase enzymes activity in brain and gills of Oreochromis niloticus. Fish were exposed for 24 and 48 h (hours) to the LC0 (non-lethal concentrations) of the malathion, chlorpyrifos and λ-cyhalothrin, respectively. For biochemical assay, a spectrophotometer was used. Glutamate oxaloacetate transaminase activity in brain and gill was significantly (p<0.05) elevated and inhibited, respectively, except in 48 h treated samples. The highest (+258%) and lowest (+8.9%) enhancement in this activity was noted in chlorpyrifos and malathion treated gill samples, respectively. The glutamate pyruvate transaminase activity was significantly (p<0.05) enhanced in all treated samples except in 24 h malathion treated brain. The highest (+340.7%) and lowest (+27%) enhancement in this level was recorded in malathion and chlorpyrifos exposed brain and gills samples. Therefore, it is suggested that both these assessments in fish different organs could be used as a useful biomarker to detect environmental pollution. Thus, the alterations in transaminases activity indicated that the tested pesticides are highly toxic to the health of aquatic organisms and should be periodically and regularly monitored in the environment to reduce pollutant stress on non-target biota, particularly fish. [ABSTRACT FROM AUTHOR]

The most widely used pesticides for residential areas and agriculture purposes, which belong to the organophosphates and synthetic pyrethroids, were evaluated in this study for their LC0 toxicity. In an aquatic environment, these pesticides are highly toxic to nontargeted organisms. Oreochromis niloticus (Nile tilapia) was selected for the bioassay tests due to its presence in the trophic levels and high bioaccumulation of the toxicants. This study evaluated the impact of pesticides on the activity of alkaline phosphatase (ALP) enzymes in the brain, gills, and muscles of O. niloticus. The fish were exposed to the LC0 concentrations of malathion (1.425 ppm), chlorpyrifos (0.125 ppm), and λ-cyhalothrin (0.0039 ppm) for 24 and 48 h. For biochemical assays, malathion, chlorpyrifos, and λ-cyhalothrin measurements were carried out using spectrophotometry. ALP activity in the brain and gills was elevated and showed significant inhibition (p < 0.05) at 24- and 48-h exposure, respectively. For the muscle tissues, a statistically important (p < 0.05) inhibition was recorded for the activity of ALP after 24- and 48-h treatments. The highest (+138%) and the lowest (+28%) enhancement in ALP activity were reported in the gills and brain tissues, which were treated with chlorpyrifos and malathion, respectively. The minimum and maximum reduction in ALP levels were noted in the 48- and 24-h malathion-treated muscle tissues, respectively. The data for the muscle tissue sample showed good consistency, because inhibition in ALP activity was noted. Therefore, the assessment of ALP activity in different organs and tissues in fish for the detection of chemical hazards in the environment is recommended. These findings confirmed that pesticides should be consistently monitored in the environment, to lower the pollutant stress on nontargeted organisms, especially fish, because the pesticides have a toxic effect on the health of aquatic organisms. [ABSTRACT FROM AUTHOR]

Escalating pesticide deposition in the aquatic environment is becoming a potential threat to aquatic organisms. Present study was designed to investigate acute toxicity in O. niloticus. the fish were exposed to five different concentrations of malathion, chlorpyrifos and lambda-cyhalothrin (synthetic pyrethroid) pesticides in the laboratory using separate aquaria for each chemical. Mortality ranged from 100 to 0%. The 24 h LC50 (median lethal concentration) for O. niloticus was 5.70, 0.5 and 0.015 ppm for malathion, chlorpyrifos and Lambda-cyhalothrin, respectively. LC50 values obtained after 24 h of exposure indicated that the fish were sensitive to all the three tested pesticides. The mortality rate was directly proportional to the pesticides concentration. The results showed that the lambda- cyhalothrin was found more toxic followed by chlorpyrifos and malathion. The study results suggested that the runoff of organophosphates and synthetic pyrethorid pesticides from nearby agricultural fields to aquatic environment posed health hazards on fish. [ABSTRACT FROM AUTHOR]