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Chronic toxicity studies were conducted with an algae (Nannochloris oculata) and the cladoceran (Daphnia magna) to determine their relative sensitivities to the thiocarbamate herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate). Most of the algal populations were initially affected by exposure to the herbicide. Thiobencarb concentrations higher than 0.5 mg/L significantly reduced algal densities after 24-h exposure. The 24-h static EC50 in D. magna was 3.01 mg/L. The sublethal effects of 0.3, 0.37, 0.5, 0.75, and 1.5 mg/L of thiobencarb concentrations on the survival, reproduction, and growth of D. magna were monitored for 21 days. The parameters used to determined the effect of the herbicide on D. magna were mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction was significantly reduced at thiobencarb concentrations of 0.30 mg/L and higher while survival was affected after exposure to 0.75 and 1.5 mg/L of the pesticide. The r value decreased with increasing concentrations of thiobencarb. Growth, as measured by body length, was depressed significantly after exposure to all herbicide concentrations tested. [ABSTRACT FROM AUTHOR]

Acute and chronic toxicity tests with the rice herbicides molinate (S‐ethyl hexahydro‐1H‐azepine‐1‐carbothioate) and thiobencarb (S‐4‐chlorobenzyl diethyl thiocarbamate) were conducted on the rotifer Brachionus calyciflorus. The 24‐hr static LC50's were 11.37 and 47.82 mg.L‐1 for molinate and thiobencarb, respectively. The effects of sublethal levels of both herbicides on the rotifer B. calyciflorus were evaluated using some demographic parameters: intrinsic rate of natural increase (r), generation time (T) and net reproductive rate (Ro). All the parameters studied decreased with increasing toxicant concentrations. The maximum acceptable toxicant concentration (MATC) was calculated for both herbicides using the intrisic rate of natural increase (r) as parameter of evaluation and the chronic data was used to calculate aplication factors (AF) of 0.062 and 0.066 mg.L‐1 for molinate and thiobencarb, respectively. Finally, the EC50 values were derived for the selected life history parameters (Ro, T, r) of B. calyciflorus after exposure to both herbicides. [ABSTRACT FROM PUBLISHER]

Acute and chronic toxicity tests with diazinon (diethyl 2‐isopropyl‐6‐methyl‐4‐pyrimidinyl phosphorothionate) were conducted on Daphnia magna. The 24‐hr static LC50 was 0.86 μL.L‐1. The sublethal effects of 0.05, 0.1, 0.5, 0.75 and 1.0 ngL‐1 of diazinon concentrations on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 x 105 cellsmL‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were: mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction as well as survival was significantly reduced at diazinon concentrations of 0.10 ngL‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of diazinon. Growth, as measured by body length, was depressed significantly at 0.05 ngL‐1 of diazinon and higher concentrations. The maximum acceptable toxicant concentration (MATC) was calculated. The chronic data was used to formulate an acute/chronic ratio. [ABSTRACT FROM PUBLISHER]

The effect of two sublethal fenitrothion concentrations (0.02 and 0.04 mg/L) on the energy metabolism of the european eel Anguilla anguilla and its recovery from intoxication was investigated. Analysis of various parameters such as glycogen, proteins and total lipids was made on liver and muscle eel tissues after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hr of fenitrothion (0,0‐dimethyl 0–3‐methyl‐4‐nitrophenyl phosphorothioate) exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144 and 192 hr in clean water, and the same parameters were again evaluated. The results obtained during the exposure to the pesticide as well as during the recovery phase were used to calculate the caloric content in both tissues of A. anguilla. A reduction in energy reserves in the selected tissues was observed after exposure to both fenitrothion concentrations and the caloric content in those animals was lower than in the controls. Most of the metabolic disorders did not persist after allowing recovery in clean water during a week. [ABSTRACT FROM PUBLISHER]

European eel (Anguilla anguilla) were exposed to sublethal fenitrothion concentrations in a continuous flow‐through system for 4 days. Muscle acetylcholinesterase (AChE) activity was evaluated after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hours pesticide exposure. Results showed that AChE activity in eel muscle tissue decreased as concentration of fenitrothion increased. Pesticide induced significant inhibitory effects on the AChE activity of A. anguilla ranging from >35% inhibition at sublethal concentration of 0.02 ppm to > 44% inhibition at sublethal concentration of 0.04 ppm. Eel were exposed to both fenitrothion concentrations for 96 hours and then allowed a period of recovery in pesticide‐free water. Samples were taken out at 8, 12, 24, 48, 72, 96, 144 and 192 hours and eel muscle AChE activity was evaluated. Following 1 week of recovery, the AChE activity for those animals previously exposed to 0.02 and 0.04 ppm fenitrothion was still different from the controls. So, the AChE activity of eel muscle at the end of the recovery phases remained significantly depressed. [ABSTRACT FROM PUBLISHER]

The bioconcentration of fenitrothion in the brain of the european eel (Anguilla anguilla) and its posterior elimination have been studied. Animals were exposed to a sublethal concentration of fenitrothion (0.04 mg/L) for 96 hours in a flow‐through test system. After this pesticide exposure, animals were transferred to clean water for 72 hours more. Bioconcentration and elimination processes of fenitrothion were studied in blood and brain. This insecticide showed a strong tendency to bioconcentrate into selected tissues. A steady‐state was observed in blood in few hours. Highest accumulation was detected in brain, where any steady‐state could be observed. Elimination started rapidly from both tissues when a recovery period was allowed. Elimination kinetics were adjusted to one‐compartment model. K2 of 0.015 and 0.044 hr‐1 were calculated for fenitrothion in blood and brain. These K2 values were related with a relatively short half‐live of fenitrothion in the analyzed tissues; probably due to the low biotransformation‐rate of this toxicant in the european eel. That fact would protect the animals against many biotransformation products even more toxics than the parent fenitrothion. [ABSTRACT FROM PUBLISHER]

Eels were exposed to a sublethal diazinon concentration of 0.042 mg/L for exposure times of 6, 24, 48, 72 and 96 hours. Biochemical analyses of blood composition, such as plasma glucose, total plasma cholesterol and triglycerides, plasma lactate, plasma urea and uric acid, showed significant differences between treated and control animals. Plasma glucose and lactate increased after 6 hours exposure to the insecticide. Plasma cholesterol and triglycerides content decreased during 96 hours treatment. Urea levels increased at 72 hours while uric acid content decreased significantly at 24, 72 and 96 hours exposure to the pesticide. The observed effects of diazinon on eel metabolism suggested that the treated fish was faced with a serious metabolic crisis, and the fish looked for alternative methods of metabolism to overcome the toxic stress. [ABSTRACT FROM PUBLISHER]

Acute and chronic toxicity tests with lindane were conducted on Daphnia magna. The 24‐hr static LC50 was 1.64 mgL‐1. The sublethal effects of 0.16, 0.25, 0.32, 0.60 and 0.80 mgL‐1 lindane on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 × 105 cellsmL‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were:mean total young per female, mean brood size, days to first brood, intrinsic rate of natural increase (r), growth, and survival. Reproduction as well as survival was significantly reduced at lindane concentrations of 0.25 mgL‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of lindane. Growth, as measured by body length, was depressed significantly at 0.25 mgL‐1 lindane and higher. The chronic data was used to formulate an acute/chronic ratio. [ABSTRACT FROM PUBLISHER]

The acute toxicities (24, 48, 72 and 96 hr) of eight pesticides to Anguilla anguilla were determined. The organochlorine pesticide, endosulfan was the most toxic, with LC50 values in the range of 0.042 to 0.041 mg/L Endosulfan was followed in order of decreasing toxicity by diazinon, fenitrothion, chlorpyrifos, lmdane, methidathion, trichlorfon and methylparathion. When fishes were exposed to the pesticides tested they exhibited signs of restlessness, erratic swimming, convulsions and difficulty in respiration. This response was more persistent in fishes exposed to organophosphorus pesticides. [ABSTRACT FROM PUBLISHER]

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5x 105 cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still reduced in F1 (1stand 3rd broods) generation daphnids from parentals (F0) exposed to 0.18 mg/L tetradifon and higher concentrations even after 21 days in clean water. However, survival was not significantly different (p>0.05) in those F1 offsprings from parentals pre-exposed to the acaricide. Growth was still reduced in F1 daphnids from parentals pre-exposed to 0.10-0.44 mg/L tetradifon. The intrinsic rate of natural increase (r) was still affected in F1 generation daphnids, specially in those from the third brood. Therefore, F1 generation D. magna offsprings from a parental generation (F0) previously exposed to the acaricide tetradifon were not able to recuperate completely when a recovery period of 21 days was allowed. [ABSTRACT FROM AUTHOR]

Acute and chronic toxicity tests with the rice herbicides molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) and thiobencarb (S-4-chlorobenzyl diethyl thiocarbarnate) were conducted on the rotifer Brachionus calyciflorus. The 24-hr static LC50's were 11.37 and 47.82 mg.L-1 for molinate and thiobencarb, respectively. The effectsof sublethal levels of both herbicides on the rotifer B. calyciflorus were evaluated using some demographic parameters: intrinsic rate ofnatural increase (r), generation time (T) and net reproductive rate (Ro). All the parameters studied decreased with increasing toxicant concentrations. The maximum acceptable toxicant concentration (MATC) was calculated for both herbicides using the intrinsic rate of naturalincrease (r) as parameter of evaluation and the chronic data was used to calculate aplication factors (AF) of 0.062 and 0.066 mg.L-1 for molinate and thiobencarb, respectively. Finally, the EC-50values were derived for the selected life history parameters (Ro, T,r) of B. calyciflorus after exposure to both herbicides. [ABSTRACT FROM AUTHOR]

The acute toxicity of the herbicide thiobencarb (S-4-chloroenzyl diethylthiocarbamate) was determined for the European eel (Anguilla anguilla). The 24, 48, 72 and 96 hours median lethal concentrations (LC50) were 25.7, 21.7, 17.0 and 13.2 mg/L, respectively. Fish were also exposed to a sublethal thiobencarb concentration (1/60 LC50-96hr=0.22 mg/L) during 96 hours in a flow-through system and then anelimination period of 192 hours in clean water was allowed. Eels were removed and blood samples taken out at each exposure time and recovery period in order to evaluate AChE activity. Thiobencarb induced significant inhibitory effects on plasma AChE activity of A. anguilla from the first contact time with the toxicant. This inhibition (under 50% activity) was maintained during the entire exposure period (96 hours and even those animals transferred to clean water showed plasma AChE activity different from the controls. Differences between total and specific AChE activity were detected during the exposure period. Total AChE activity in the plasma from animals transferred to a mediumfree of toxicant recovered its normal value while specific AChE activity remained depressed (<50%) until five days later. [ABSTRACT FROM AUTHOR]

Acute and chronic toxicity tests with diazinon (diethyl 2-isopropyl-6-methyl-4-pyrimidinyl phosphorothionate) were conducted on Daphnia magna. The 24-hr static LC50 was 0.86 5L.L-1. The sublethaleffects of 0.05, 0.1, 0.5, 0.75 and 1.0 ngL-1 of diazinonconcentrations on the survival, reporduction and growth of D. magna were monitored for 21 dyas. The algae Nannochloris oculata (5 x 105 cellsmL-1) was used to feed the daphnids. The parameters used to determine the effect of the pesticide on D. magna were: mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction as well as survival was significantly reduced at diazinon concentrations of 0.10 ngL-1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of diazinon. Growth, as measured by body length, was depressed signficantly at 0.05 ngL-1 of diazinon and higher concentrations. Themaximum acceptable toxicant concentration (MATC) was calculated. Thechronic data was used to formulate an acute/chronic ratio. [ABSTRACT FROM AUTHOR]

The effect of two sublethal fenitrothion concentrations (0.02 and 0.04 mg/L) on the energy metabolism of the european eel Anguilla anguilla and its recovery from intoxication was investigated. Analysis of various parameters such as glycogen, proteins and total lipids was made on liver and muscle eel tissues after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hr of fenitrothion (0,0-dimethyl 0-3-methyl-4-nitrophenyl phosphorothioate) exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144 and 192 hr in clean water, and the same parameters were again evaluated. The results obtained duringthe exposure to the pesticide as well as during the recovery phase were used to calculate the caloric content in both tissues of A. anguilla. A reduction in energy reserves in the selected tissues was observed after exposure to both fenitrothion concentrations and the caloric content in those animals was lower than in the controls. Most of the metabolic disorders did not persist after allowing recovery in clean water during a week. [ABSTRACT FROM AUTHOR]

This study was undertaken to determine the bioconcentration-elimination process of fenitrothion in the liver of the european eel (Anguilla anguilla). The animals were exposed to two sublethal fenitrothion concentrations corresponding to 1/5 and 1/10 of LC50 96-h in a flow-through test system. Uptake kinetics were determined from liver burdens measured at 2, 8, 24, 48, 56, 72 and 96 hours exposure. After pesticide exposure, animals were transferred to clean water for 72 hours. Fenitrothion elimination was determined after 12, 24, 48 and 72 hours of recovery period. The insecticide showed a high bioconcentration tendency. Steady-state was reached after 48 hours exposure when the animals where exposed to the lowest concentration. This was followed with a rapid elimination process when the animals were transferred to clean water. Animals exposed to 0.04 ppm showed an early accumulation of the toxicant into the liver, and a steady-state was reached after 8 hours. The elimination rate constant K2 of 0.0096 h-1 and 0.06 h-1 were estimated from the data. The biotransformation rate of fenitrothion in the European eel were low as indicated by a relatively short half-life (11.55 h) of the insecticide. An increase in the Hepatosomatic Index was observed after 96 hours of exposure, but no significant differences were found between control and exposed animals. [ABSTRACT FROM AUTHOR]

European eel (Anguilla anguilla) were exposed to sublethal fenitrothion concentrations in a continuous flow-through system for 4 days. Muscle acety1cholinesterase (ACNE) activity was evaluated after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hours pesticide exposure. Results showedthat ACNE activity in eel muscle tissue decreased as concentration of fenitrothion increased. Pesticide induced significant inhibitory effects on the ACNE activity of A. anguilla ranging from >35% inhibition at sublethal concentration of 0.02 ppm to > 44% inhibition at sublethal concentration of 0.04 ppm. Eel were exposed to both fenitrothionconcentrations for 96 hours and then allowed a period of recovery inpesticide-free water. Samples were taken out at 8, 12, 24, 48, 72, 96, 144 and 192 hours and eel muscle ACNE activity was evaluated. Following 1 week of recovery, the ACNE activity for those animals previously exposed to 0.02 and 0.04 ppm fenitrothion was still different from the controls. So, the ACNE activity of eel muscle at the end of therecovery phases remained significantly depressed. [ABSTRACT FROM AUTHOR]

The bioconcentration of fenitrothion in the brain of the european eel (Anguilla anguilla) and its posterior elimination have been studied. Animals were exposed to a sublethal concentration of fenitrothion (0.04 mg/L) for 96 hours in a flow-through test system. After this pesticide exposure, animals were transferred to clean water for 72 hoursmore. Bioconcentration and elimination processes of fenitrothion were studied in blood and brain. This insecticide showed a strong tendency to bioconcentrate into selected tissues. A steady-state was observed in blood in few hours. Highest accumulation was detected in brain,where any steady-state could be observed. Elimination started rapidly from both tissues when a recovery period was allowed. Elimination kinetics were adjusted to one-compartment model. K2 of 0.015 and 0.044 hr-1 were calculated for fenitrothion in blood and brain.These K2 values were related with a relatively short half-live of fenitrothion in the analyzed tissues; probably due to the low biotransformation rate of this toxicant in the european eel. That fact would protect the animals against many biotransformation productseven more toxics than the parent fenitrothion. [ABSTRACT FROM AUTHOR]