Sublethal effects of profenofos on locomotor behavior and gill architecture of the mosquito fish, Gambusia affinis

Subacute studies of profenofos on mosquito fish, Gambusia affinis, were carried out for 20 days to assess the locomotor behavior and structural integrity of gill in relation to bioaccumulation and targeted enzyme acetylcholinesterase (AChE; EC 3.1.1.7). The sublethal concentration of 0.13 mg/L (1/5 of LC50) altered locomotor behavior such as distance traveled and swimming speed in exposed fish. This could be due to inhibition in the activity of acetylcholinesterase and deformities in the primary and secondary lamella of gill. The bioaccumulation values indicated that the accumulation of profenofos was highest in viscera followed by head and body. The average bioconcentration factor values are 254.83, 6.18, and 2.52 microg/g for viscera, head, and body. The findings revealed that profenofos is highly toxic even at sublethal concentrations to the mosquito fish, Gambusia affinis.     

Locomotor Behavioral Response of Mosquitofish (Gambusia affinis) to Subacute Mercury Stress Monitored by Video Tracking System

Locomotor behavior is commonly affected by contaminants, and the pattern of fish swimming is a highly organized species-specific response. In the current study, we examined the locomotor behavioral response of the mosquitofish, Gambusia affinis, which was exposed to a sublethal concentration (LC₅, 20 μg/L) of mercuric chloride (HgCl₂) for 28 days and monitored using a computer vision system. The EthoVision video tracking system for automation of behavioral studies at regular intervals revealed abnormal locomotor behavior such as reduction in swimming speed (cm/s) and distance traveled per unit time. The effects of this metal on the gill morphology and bioaccumulation in different body parts were also investigated. High-resolution microscopy studies revealed abnormal gill morphology, with fusion of primary lamellae along with deep lesions and erosions in the secondary lamellae. The bioaccumulation concentrations in head, body, and viscera were determined by cold vapor atomic absorption spectrometric technique at regular intervals. The results indicated that the accumulation of mercury was the highest in viscera followed by head and body, with bioconcentration factors (BCFs) of 3.99, 2.18, and 1.57 and uptake rate constants (k₁) of 17.91, 11.02, and 8.13, respectively. These observations indicate that alterations in fish behavior under subacute stress can provide important information useful in predicting the stress.     

Locomotor behavioral response of mosquitofish (Gambusia affinis) to subacute mercury stress monitored by video tracking system

Locomotor behavior is commonly affected by contaminants, and the pattern of fish swimming is a highly organized species-specific response. In the current study, we examined the locomotor behavioral response of the mosquitofish, Gambusia affinis, which was exposed to a sublethal concentration (LC(5), 20 microg/L) of mercuric chloride (HgCl2) for 28 days and monitored using a computer vision system. The EthoVision video tracking system for automation of behavioral studies at regular intervals revealed abnormal locomotor behavior such as reduction in swimming speed (cm/s) and distance traveled per unit time. The effects of this metal on the gill morphology and bioaccumulation in different body parts were also investigated. High-resolution microscopy studies revealed abnormal gill morphology, with fusion of primary lamellae along with deep lesions and erosions in the secondary lamellae. The bioaccumulation concentrations in head, body, and viscera were determined by cold vapor atomic absorption spectrometric technique at regular intervals. The results indicated that the accumulation of mercury was the highest in viscera followed by head and body, with bioconcentration factors (BCFs) of 3.99, 2.18, and 1.57 and uptake rate constants (k1) of 17.91, 11.02, and 8.13, respectively. These observations indicate that alterations in fish behavior under subacute stress can provide important information useful in predicting the stress.     

Toxic effects of profenofos on tissue acetylcholinesterase and gill morphology in a euryhaline fish,<Emphasis Type="Italic"> Oreochromis mossambicus</Emphasis>

Acute and sub-acute studies of profenofos [ O-(4-bromo-2-chlorophenyl)- O-ethyl- S-propyl phosphorothioate] on fish, Oreochromis (Tilapia) mossambicus, were carried out to assess the toxicity in relation to behaviour, morphology, and interactions with the targeted enzyme acetylcholinesterase (AChE, EC 3.1.1.7). Profenofos can be rated as highly toxic to O. mossambicus, with a median lethal concentration (LC(50)) of 0.272+/-0.0177 mg/l. The inhibitory and recovery pattern of brain and gill AChE was studied in vivo after exposure to a single LC(50) and multiple exposures to sub-lethal concentrations (0.108 mg/l) for 28 days, respectively. The LC(50)-exposed fish exhibited 90% inhibition of AChE activity in brain and gill in 24 h, and completely recovered within 23 days. Electron microscopy studies revealed an abnormal gill morphology, with distinct breakages in gill arches and rakers, along with deep lesions and erosions in the epithelium. Prolonged exposure at 0.108 mg/l also had similar effects, such as gill damage and AChE inhibition. The in vitro AChE study indicated that profenofos is neurotoxic and that it alters the apparent K(m) values widely in a concentration-dependent manner, resulting in a competitive type of inhibition. Based on the K(i) values, the sensitivity of AChE in brain was greater than that in gill tissue, at 2.38 x 10(-5) and 4.62 x 10(-5) M, respectively. The bioaccumulation values in head, body and viscera were estimated at regular intervals by gas chromatography method. The results indicated that the accumulation of profenofos was the highest in viscera followed by head and body, with depuration rates of 6.14, 0.16 and 0.12 micro g/h, respectively.     

Toxic effects of chlorpyrifos on antioxidant enzymes and target enzyme acetylcholinesterase interaction in mosquito fish, Gambusia affinis

The recovery effect of chlorpyrifos (CPF) on antioxidant enzymes, locomotor behaviour and the target enzyme acetylcholinesterase (AChE) interaction were studied after exposure to 297μgL(-1) (LC(50) for 96h) in mosquito fish, Gambusia affinis. Activities of the antioxidant enzymes-superoxide dismutase, catalase, glutathione reductase in viscera, and AChE in brain were inhibited at 96h of exposure. However, induction in lipid peroxidation was observed. The antioxidant levels were restored to near control by 16-18 days. Similarly, swimming speed and AChE were also recovered but comparatively needs longer period. In vitro AChE study indicated that CPF alters the apparent K(m) values, resulting in a competitive type of inhibition and the inhibitory constant K(i) was found to be 4.57×10(-4)M. The results showed that the organophosphate CPF besides its inhibitory effect on target enzyme AChE also inhibits antioxidant enzymes, which can be used as biomarkers in the pesticide-contaminated aquatic streams.     

INFLUENCE OF TEMPERATURE AND DISSOLVED OXYGEN ON THE ACUTE TOXICITY OF PROFENOFOS TO FATHEAD MINNOWS (PIMEPHALES PROMELAS)

ABSTRACT

The purpose of this study was to investigate the influence of temperature and dissolved oxygen levels on the acute toxicity of profenofos to fathead minnows (Pimephales promelas). Exposure conditions were as follows: normal temperature and normal dissolved oxygen (NTNO; 20 ± 2°C and 6.0–9.0 mg/L, respectively); normal temperature and low dissolved oxygen (NTLO; 20 ± 2°C and 1.7–2.6 mg/L, respectively); high temperature and normal dissolved oxygen (HTNO; 30 ± 2°C and 6.6–6.9 mg/L, respectively); high temperature and low dissolved oxygen (HTLO; 30 ± 2°C and 1.5–3.0 mg/L, respectively). Initial 96-h acute toxicity studies with profenofos were conducted at NTNO and HTLO exposure conditions. The 96-h LC₅₀ at NTNO was 333 µg/L with 95% confidence limits ranging from 244 to 558 µg/L. However, the 96-h LC₅₀ at HTLO was significantly lower at 21.5 µg/L with 95% confidence limits ranging from 17.4 to 28.8 µg/L. Acetylcholinesterase (AChE) activity was measured in the head and torso of surviving fish at 96-h. A weak dose-related decrease in AChE was observed at NTNO but no dose–response relationship was observed at HTLO exposure condition. Additional experiments were conducted using 50 µg/L profenofos at NTNO, NTLO, HTNO, and HTLO exposure conditions. Mortality, sublethal effects (erratic and hyperactive swimming), and AChE activity in the head and torso were measured at 2, 4, and 12-h following exposure to profenofos. No mortality or significant sublethal effects were observed in controls or profenofos-treated groups in NTNO and NTLO exposure conditions. However, significant mortality and sublethal effects were observed in profenofos-treated fish in HTNO at 12 h and at all time points in HTLO. Both high temperature and low dissolved oxygen, as well as combinations of high temperature and low dissolved oxygen significantly decreased AChE activity in control fish. Exposure to 50 µg/L profenofos in all exposure conditions further decreased AChE activity, but no apparent correlations between mortality and AChE activity were observed. These results suggest that the acute toxicity of profenofos to fathead minnows may be exacerbated during summer conditions in southern U.S. aquatic ecosystems.     

Estimation of low chlorpromazine concentrations by surfacing and sinking reaction of minnows (Gambusia affinis)

Surfacing and sinking reactions of minnows (Gambusia affinis) allow the determination of chlorpromazine in aqueous solutions down to concentrations of 0.1 g/ml. In a given volume of solution, neither sex nor number of the fish per tube have any effect on their response to the low doses. A twenty-fold augmentation in volume causes a two-fold increase in sensitivity. The time elapsing, from the beginning of immersion until onset of surfacing, increases with decreasing drug concentration. Partial recovery from the drug is obtained after washing of fish with tap water. Adaptation occurs when the fish are immersed for more than 48 hrs.Deceased on January 23, 1970.     

Influence of temperature and dissolved oxygen on the acute toxicity of profenofos to fathead minnows (Pimephales promelas)

The purpose of this study was to investigate the influence of temperature and dissolved oxygen levels on the acute toxicity of profenofos to fathead minnows (Pimephales promelas). Exposure conditions were as follows: normal temperature and normal dissolved oxygen (NTNO; 20 +/- 2 degrees C and 6.0-9.0 mg/L, respectively); normal temperature and low dissolved oxygen (NTLO; 20 +/- 2 degrees C and 1.7-2.6 mg/L, respectively); high temperature and normal dissolved oxygen (HTNO; 30 +/- 2 degrees C and 6.6-6.9 mg/L, respectively); high temperature and low dissolved oxygen (HTLO; 30 +/- 2 degrees C and 1.5-3.0 mg/L, respectively). Initial 96-h acute toxicity studies with profenofos were conducted at NTNO and HTLO exposure conditions. The 96-h LC50 at NTNO was 333 micrograms/L with 95% confidence limits ranging from 244 to 558 micrograms/L. However, the 96-h LC50 at HTLO was significantly lower at 21.5 micrograms/L with 95% confidence limits ranging from 17.4 to 28.8 micrograms/L. Acetylcholinesterase (AChE) activity was measured in the head and torso of surviving fish at 96-h. A weak dose-related decrease in AChE was observed at NTNO but no dose-response relationship was observed at HTLO exposure condition. Additional experiments were conducted using 50 micrograms/L profenofos at NTNO, NTLO, HTNO, and HTLO exposure conditions. Mortality, sublethal effects (erratic and hyperactive swimming), and AChE activity in the head and torso were measured at 2, 4, and 12-h following exposure to profenofos. No mortality or significant sublethal effects were observed in controls or profenofos-treated groups in NTNO and NTLO exposure conditions. However, significant mortality and sublethal effects were observed in profenofos-treated fish in HTNO at 12 h and at all time points in HTLO. Both high temperature and low dissolved oxygen, as well as combinations of high temperature and low dissolved oxygen significantly decreased AChE activity in control fish. Exposure to 50 micrograms/L profenofos in all exposure conditions further decreased AChE activity, but no apparent correlations between mortality and AChE activity were observed. These results suggest that the acute toxicity of profenofos to fathead minnows may be exacerbated during summer conditions in southern U.S. aquatic ecosystems.     

Sublethal Effects of Organophosphate Diazinon on the Brain of Cyprinus Carpio

Effects of diazinon, at different concentrations and exposure times, were investigated in freshwater fish, Cyprinus carpio, to elucidate the possible mode of action on lipid peroxidation together with the inhibitory effect of diazinon on acetylcholinesterase activity and changes in tissue protein levels. Cholinesterase inhibition is considered to be a specific biomarker of exposure to organophosphorus pesticides. Fish were exposed to 0.0036 μg/L, 0.018 μg/L, and 0.036 μg/L (sublethal) concentrations of diazinon for 5, 15, and 30 days, and biochemical measurements were carried out spectrophotometrically. Brain was chosen as an indicator tissue because it is a target system for the organophosphorus action. More than 20% decline in acetylcholinesterase activity relative to mean activity of the controls was observed in the diazinon-exposed groups. Protein content decreased significantly after 15 days of exposure to 0.018 μg/L and 0.036 μg/L diazinon and after 30 days of exposure to 0.036 μg/L. Malondialdehyde level declined markedly compared with the control levels. This study showed that prolonged exposures of C. carpio to diazinon had significant effects on brain acetylcholinesterase activity and that environmentally relevant concentrations of diazinon can significantly inhibit brain acetylcholinesterase activity. Altered protein content was probably due to the high energy demand under pesticide stress or inhibition of de novo enzyme synthesis. The decreased malondialdehyde content may reflect the possibility of better protection against oxidative stress.     

Toxicity, bioaccumulation and metabolism of phenol in the freshwater fish Oreochromis mossambicus

The acute toxicity of phenol was determined to be 35.0 mg/l in Oreochromis mossambicus. The fish were exposed to two sublethal concentrations of phenol (2.3 and 3.5 mg/l) for 30 days. The effects of exposure were studied on the bioaccumulation and elimination of phenol from the kidney and biochemical parameters of liver, gill, and muscle at intervals of 10, 20, and 30 days. A statistically significant increase in phenol concentration was noted in tissues from all treated fish groups. Bioaccumulation and biochemical changes were dose and duration dependant. Recovery in fish after post exposure was observed after transferring these fish to normal tap water for 30 days. Elimination of phenol was noted, although the concentration of phenol remained significantly higher than the control after 30 days of the experiment. Total protein, total carbohydrate, and total lipids in the tissues of liver, gill, and muscle of fish decreased greatly. The longer the exposure time, the greater was the percentage reduction of organic matter of the fish exposed to the sublethal concentration of phenol.     

Acute toxicity,behavioral and nitrogen metabolism changes of sodium cyanide affected on tissues of Tilapia mossambica (Perters)

The toxicity of sodium cyanide to the freshwater fish, Tilapia mossambica, was studied using the static bioassay method. The LC₅₀ value at 96 hours was found to be 44.33 µg/L (normal concentration is 25 µg/L). Behavioral changes, when exposed to a lethal concentration of sodium cyanide, showed increased opercular movement, increased surface behavior, loss of equilibrium, change in body color, increased secretion of mucus, irregular swimming activity, rapid jerk movement, “S” jerk, partial jerk, and aggressiveness. A decrease in ammonia level of gill (67.56%), muscle (63.88%), and liver (53.29%) with increased levels in urea gill (75.83%), muscle (63.53%), and liver (107.49%) was observed in a lethal concentration of sodium cyanide at the end of day 4 of exposure. In a sublethal concentration (4.43 μg/L), a decreasing trend in ammonia level continued up to day 15. Urea level at days 1 and 5 decreased on days 1 and 5, but increased on days 10 and 15.     

Inhibition of ATPase activity in the freshwater fish Labeo rohita (Hamilton) exposed to sodium cyanide

Present study concerns the effect of sodium cyanide on the Indian major carp, Labeo rohita. Fishes were exposed to lethal (0.32?mg/L) and sublethal (0.064?mg/L) concentrations of sodium cyanide. The effect of intoxication was studied on Na⁺K⁺ATPase, Mg⁺²ATPase and Ca²⁺ATPase in various physiological tissues (gill, liver, and muscle) at the end of 1, 2, 3 and 4 days of lethal and 5, 10 and 15 days of sublethal exposure periods. Sodium cyanide induced significant inhibitory effects on the ATPase activity of the fish. Inhibition of the ATPase blocked the active transport system of the gill epithelial as well as chloride cells, and thus altered the osmo-regulatory mechanism of the fish. The value of the measured responses as an indicator of stress caused by water contamination discussed. The results confirm that ATPase levels significantly decreased in treated fish, indicating that ATPases could be used as sensitive and useful biomarkers for cyanide pollution.     

Genotoxic effects of profenofos on the marine fish, Therapon jarbua

Profenofos (EC(50)) is a persistent and toxic organophosphorus insecticide. Animals get exposed to profenofos via food and water. The present study was designed to explore the genotoxic effect of profenofos in the marine fish. The ubiquitously occurring marine fish, Therapon jarbua, was exposed to profenofos and its effect on DNA was measured using comet (single-cell gel electrophoresis) assay. DNA damage were scored using mean percentage of tail length and compared with the comet classes' viz., 0, 1, 2, 3, and 4. In the first three doses, the (21.5, 43.0 and 86.0 μg L(-1)) comets were observed, of which the mean tail length differed significantly (p?相似文献   

Uptake,biotransformation, and elimination of rotenone by bluegills (Lepomis macrochirus)

Yearling bluegills (Lepomis macrochirus) were exposed to sublethal concentrations of [¹⁴C]rotenone (5.2 μg/l) for 30 days in a continuous flow exposure system and then transferred to clean, flowing water for an additional 21-day depuration period. Rates of uptake and elimination and profile of the rotenoid metabolites in head, viscera, and carcass components were evaluated by ¹⁴C counting and by high performance liquid chromatography. Total [¹⁴C]rotenone derived activity was relatively uniform in all body components within 3 days after initial exposure and remained constant during the ensuing 27 days of exposure. Initial uptake rate coefficients were highest in viscera (K_u = 80 · h^?1) and were nearly identical for head (K_u = 14 · h^?1) and carcass (K_u = 10 · h^?1). Analyses of tissue extracts by high performance liquid chromatography confirmed the presence of at least six biotransformation products of rotenone. More than 60% of the activity extracted from viscera was present as a single peak which represented a compound that was extremely soluble in water. Rotenone composed only 0.3% of the extractable activity in viscera taken from fish exposed to rotenone for 30 days; however, rotenone accounted for 15.4% of extractable activity in the head and 20.1% in the carcass components. Rotenolone and 6′,7′-dihydro-6′,7′-dihydroxyrotenolone were tentatively identified as oxidation products in all tissue extracts.Elimination of ¹⁴C activity from all body components was biphasic; both phases followed first-order kinetics. The rate of elimination was nearly equal for all body components during the initial phase but was most rapid from viscera during the second phase of elimination. Bioconcentration factors for the head, viscera, and carcass were 165, 3,550, and 125, respectively, when calculated on the basis of total ¹⁴C activity but only 25.4, 11, and 26 when calculated as the concentration of parent material.     

A seasonal study of microsomal mixed-function oxidase components in insecticide-resistant and susceptible mosquitofish, Gambusia affinis.

The mixed-function oxidase components which are involved in xenobiotic hydroxylations were studied in liver microsomes from two populations of mosquitofish (Gambusia affinis) for 26 months. One population is highly resistant to organochlorine insecticides and is exposed periodically to agricultural chemical contamination; the other population is susceptible to these chemicals and is not exposed to such pollutants. The following parameters were measured: cytochromes P-450 and b₅; NADPH-cytochrome c, NADPH-dichloroindophenol, NADH-cytochrome c, and NADH-cytochrome b₅ reductases; liver weight to body weight ratios; and microsomal protein. Most parameters demonstrated seasonal cycles with the highest values occurring during the late fall and winter. The cyclic nature of the parameters investigated may be the result of the relative magnitude of microsomal hydroxylations during the year in relationship to other microsomal processes such as biosynthesis. The range of concentrations or specific activities of most of the components was about the same for both fish populations, although the resistant fish possessed relatively larger livers and, therefore, greater amounts of these microsomal components than the susceptible fish. The results suggest the induction of these microsomal oxidase components in the resistant population during their annual exposure to environmental pollutants in the agricultural runoff.     

Genotoxic effects of produced waters in mosquito fish (Gambusia affinis)

The aim of this study was to assess the potential genotoxic effects of produced water (PW) from an Italian on-shore oil plant. Produced water is a complex mixture containing residual hydrocarbons, trace elements, naturally occurring radioactive material and potentially toxic treatment chemicals such as biocides, dispersants, detergents and scale inhibitors used in oil production. The test organism, mosquito fish (Gambusia affinis), was divided into male and female groups and exposed for 8 days in the laboratory to 50% concentrations of different produced waters: PW before treatment and after settling treatment. The fish were also exposed to lower concentrations (10%) of the same PW for 30 days. DNA damage was evaluated in erythrocytes by single cell gel electrophoresis (Comet assay) and micronucleus test, while an oxidative stress biomarker, was assessed. Polycyclic aromatic hydrocarbons (PAH) metabolites in bile were also evaluated. A higher sensitivity in biomarker responses was found in females in comparison to males. An increase in DNA strand breaks was observed in both genders after 30 days exposure and a statistically significant increase of micronucleated cells was found in females after 8 days exposure. A positive correlation between presence of micronucleated cells and PAH metabolites in bile was also observed.     

Does persistent organic pollutant PFOS (perfluorooctane sulfonate) negative impacts on the aquatic invertebrate organism,Astacus leptodactylus [Eschscholtz, 1823]

Highly persistent perfluorooctane sulfonate (PFOS) is an industrial fluorinated organic chemical with significant bioaccumulation and biomagnification properties. The purpose of this study was to determine the toxic effects of sublethal PFOS on the aquatic invertebrate organism, narrow-clawed crayfish [Astacus leptodactylus Eschscholtz, 1823]. The 96?h LC₅₀ value was determined as 48.81?mg/L (34.19–63.68?mg/L) with probit analysis. The sublethal experimental design was formed into four groups solvent control (DMSO, dimethyl sulphoxide), non-treated control group, and 1/10 (5?mg/L) and 1/100 (0.5?mg/L) of 96?h LC₅₀ of PFOS, and crayfish were exposed for 48?h, 7?d, and 21?d under laboratory conditions. Total haemocyte counts (THCs) decreased, while the haemolymph total antioxidant status (TAS) values increased (p?<?0.05) after exposure to 0.5 and 5?mg/L PFOS for 48?h, 7?d, and 21?d. Haemolymph total oxidative stress (TOS) levels significantly increased at 5?mg/L PFOS concentration (p?<?0.05). Catalase (CAT) activities increased at both concentrations after 48?h and 7?d and then returned to control levels after 21?d; whereas superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities did not change in muscle tissue (p?>?0.05). GPX and CAT activities decreased, but SOD activity increased in hepatopancreas tissue (p?<?0.05). SOD activity at both concentrations and CAT activity at 5?mg/L PFOS exposure decreased in gill tissue, while GPX activity increased at both concentrations of 48?h and 7?d and returned to control values on day 21 of exposure. Histopathological alterations were detected in hepatopancreas and gill tissues. Lamellar deformations, epithelial hyperplasia, and haemocytic infiltrations were observed in the gill tissues, whereas tubular degeneration, tubule loss, necrosis, and lesions in the hepatopancreas tissues were the major recorded alterations. As a result, the sublethal concentrations of PFOS have toxic effects on crayfish and histologically cause tissue damage. Our findings also support a better understanding of the early toxicological effects of PFOS in freshwater ecosystems. Also, it could be concluded that A. leptodactylus is a reliable model for examining histopathological alterations and differences in enzyme activities together with the haemolymph findings in toxicology studies amid aquatic species.

     

In vivo and in vitro retention of [14C]aldrin and [14C]dieldrin in cellular fractions from brain and liver tissues of insecticide-resistant and susceptible Gambusia

Aldrin and dieldrin-resistant and susceptible populations of mosquitofish (Gambusia affinis) were assayed for aldrin and dieldrin retention in particulate fractions of livers and brains following in vivo and in vitro treatment with [¹⁴C]aldrin and [¹⁴C]dieldrin. In the in ivvo studies there was a highly significant difference in retention between all particulate fractions of susceptible and resistant fish brains. In the in vitro studies the corresponding difference was less or entirely absent. This study offers indirect evidence for a membrane barrier to both aldrin and dieldrin in the brains of resistant fish.     

Genotoxicity assessment of carp (Cyprinus carpio L.) fingerlings by tissue DNA damage and micronucleus test,after environmental exposure to fenitrothion

The purpose of this study was to evaluate the adverse effects of sublethal doses of fenitrothion, an organophosphothionate insecticide on brain, gill, liver, and muscle tissues as a ratio of 8-OHdG to dG to indicate the DNA damage and erythrocyte micronucleus frequency for genotoxicity of carp (Cyprinus carpio L.) fingerlings. In our study, the mean weights and lengths of the fish (n?=?4–12) were 31.13?±?14.24?g and 12.53?±?1.41, respectively. Before the experiment, fish were maintained in aerated dechlorinated tap water at 21.8?±?1°C and fed daily with commercial feed at a rate of 2% of their body weights. Experiments were conducted under static conditions in the aquaria. Technical grade (95%) fenitrothion was diluted in acetone to give a dosing solution of 10?mg/L. The increased lesions/10⁶ DNA bases (p?<?0.05) of liver tissue of exposure group (0.49?±?0.18) was observed when compared to control group (0.28?±?0.30). There was not any significant differences between brain tissues, no damage were detectable in gill and muscle tissues of control groups, and in exposure groups altered levels of damage were detected for gill (0.06?±?0.05) and muscle (0.16?±?0.21) tissues. The increased micronucleus frequencies (%) in erythrocytes of carp following the exposure to 48?h fenitrothion (6.43?±?3.89; p<0.05) was observed when compared to control group (1.29?±?1.03). The available data indicate that there is still lack of well-established dose–response relationships between occupational or environmental exposures and the induction of 8-OHdG. Such biomarkers may be used in assessing adverse/toxic effects of pesticides as environmental stressors.