Investigation of acute toxicity and the effect of cadmium chloride (CdCl2 . H2O) metal salt on behavior of the guppy (Poecilia reticulata)

In this study 96-h LC50 value of cadmium chloride (CdCl2 . H2O), a metal salt widely used in industry, was determined for the guppy (Poecilia reticulata, Pallas, 1859). The experiments were planned in four series of a total of 440 guppies employing the static test method of acute toxicity. 10 fish were placed in each replicate of each dose. The experiments were performed as four replicates, and behavioral changes in the guppy were determined for each cadmium chloride metal salt concentration. The data obtained were statistically evaluated by the use of EPA computer program based on Finney's Probit Analysis Method and a 96-h LC50 value for P. reticulata was found to be 30.4 mg/l in a static bioassay test system. This value was estimated to be 30.6 mg/l with Behrens-Karber's method. The two methods were in good agreement. 95% lower and upper confidence limits for the LC50 were 29.3 and 31.7 mg/l, respectively. The water temperature was kept between 21 and 23 degrees C. The behavioral changes observed in fish were, swimming in imbalanced manner, capsizing, attaching to the surface, difficulty in breathing and gathering around the ventilation filter.     

Investigation of acute toxicity of cadmium sulfate (CdSO4 x H2O) and behavioral changes of grass carp (Ctenopharyngodon idellus Val., 1844)

This study attempts to determine the 96-h LC50 values of CdSO4 x H2O, a metal salt widely used in industry, for grass carp (Ctenopharyngodon idellus Val., 1844). The study was carried out in two stages with 120 grass carp individuals using statistic method of aquatic toxicity. In addition, the behavioral changes of grass carp at different CdSO4 x H2O concentrations were determined. The results were evaluated using probit analysis method and the LC50 value for grass carp species was calculated as 9.42 mg/l.     

Investigation of acute toxicity of fenitrothion on peppered corydoras (Corydoras paleatus) (Jenyns, 1842)

Fenitrothion, as an organophosphothionate insecticide, is a contact insecticide and selective acaricide, also used as a vector control agent for malaria in public health programs. A 96 h LC50 value of fenitrothion, a potential toxic pollutant contaminating aquatic ecosystems, was determined on the adult peppered corydoras (Corydoras paleatus). The experiments were repeated three times. The static test method of acute toxicity test was used. Water temperature was regulated at 23 +/- 1 degrees C. In addition, behavioral changes at each fenitrothion concentration were observed for the individual fish. Data obtained from acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The 96 h LC50 value for peppered corydoras was estimated as 3.51 mg/l.     

Acute toxicity of alpha-cypermethrin to guppy (Poecilia reticulata, Pallas, 1859)

Alpha-cypermethrin is a synthetic pyrethroid insecticide used to control pests in domestic, industrial and agricultural situations. Adult male guppy fish (Poecilia reticulata standard test species) were selected for the bioassay experiments. The experiments were performed in four series and the 96-h LC50 value was determined for guppies. The acute toxicity experiments were carried out by static method and behavioral changes in guppies were determined for each alpha-cypermethrin (98% technical grade) concentration. Data obtained from the alpha-cypermethrin investigation were evaluated by the use of probit analysis statistical method and the 96-h LC50 value for guppy was estimated as 9.43 microg/l.     

Investigation of acute toxicity and the effect of 2,4-D (2,4-dichlorophenoxyacetic acid) herbicide on the behavior of the common carp (Cyprinus carpio L., 1758; Pisces,Cyprinidae)

A 96-h LC(50) values of 2,4-D [(2,4-dichlorophenoxy)acetic acid], a common contaminating agricultural herbicide, were determined on the adult common carp (Cyprinus carpio L., 1758; Pisces, Cyprinidae). The study was conducted in two stages using 130 carp. The data obtained were statistically evaluated by the use of the EPA computer program based on Finney's Probit Analysis Method and a 96-h LC(50) value for C. carpio L., 1758 was found to be 63.24 mg/l in a static bioassay test system. 95% lower and upper confidence limits for the LC(50) were 55.03 and 71.92 mg/l, respectively. Water temperature was 17+/-1 degrees C. Behavioral changes of the above mentioned species were examined for various herbicide concentrations.     

Genotoxicity assessment of acute exposure of chlorpyrifos to freshwater fish Channa punctatus (Bloch) using micronucleus assay and alkaline single-cell gel electrophoresis

Chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridylphosphorothioate) is one of the organophosphate pesticides widely used in agricultural practices throughout world and irreversible inhibitor of cholinesterase in all animal species. Limited efforts have been made to study acute genotoxic effects of chlorpyrifos (CPF) in different tissues of fish using genotoxic biomarkers. Therefore, the present investigation was aimed to study the induction of DNA damage by CPF in freshwater teleost fish Channapunctatus using micronucleus assay (MN assay) and alkaline single-cell gel electrophoresis (comet assay). The value of LC(50) - 96 h of CPF was determined as 811.98 microgl(-1) for C. punctatus, in a semi-static system and on the basis of LC(50) value three acute concentrations viz., 203, 406 and 609 microgl(-1) were determined. The fishes were exposed to the different concentrations of CPF for 96 h and samplings were done at regular intervals for assessment of the MN frequencies and DNA damage. In general, significant effects (P<0.01) from both concentrations and time of exposure were observed in exposed fishes. It was found that the micronucleus induction was highest on 96 h at all concentrations in the peripheral blood. Similar trend was observed for the DNA damage measured in terms of the percentage of tail DNA in the lymphocyte and gill cells. This study explored the combined use of micronucleus assay and comet assay for in vivo laboratory studies using fresh water fish for screening the genotoxic potential of xenobiotics.     

Lethal and sublethal effects of the pyrethroid, bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 microg/L (95% CI: 0.015-0.025 microg/L) and for larval shrimp was 0.013 microg/L (95% CI: 0.011-0.016 microg/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 microg/L (95% CI: 11.886-47.250 microg/L). The 24-h sediment LC50 for adult shrimp was 0.339 microg/L (95% CI: 0.291-0.381 microg/L) and for larval shrimp was 0.210 microg/L (95% CI: 0.096-0.393 microg/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.     

Comparison of arsenate and cadmium toxicity in a freshwater amphipod (Gammarus pulex)

Cadmium is largely documented on freshwater organisms while arsenic, especially arsenate, is rarely studied. The kinetic of the LC50s values for both metals was realized on Gammarus pulex. Physiological [i.e. metal concentration in body tissues, bioconcentration factor (BCF)] effects and behavioural responses (via pleopods beats) were investigated after 240-h exposure. Arsenate LC50 value was 100 fold higher than Cd-LC50 value after 240-h exposure, while concentrations in gammarids were similar for both metals at their respective LC50s. BCF decreased with increasing cadmium concentration while BCF remained stable with increasing arsenate concentration. Moreover, BCF was between 148 and 344 times lower for arsenate than cadmium. A significant hypoventilation was observed for cadmium concentrations exceeding or close to the 240h-LC50(Cd), while gammarids hyperventilated for the lowest arsenate concentrations and hypoventilated for the highest arsenate concentrations. We discussed the relationships between potential action mechanisms of these two metals and observed results.     

Effects of cadmium, copper, lead and zinc on growth, reproduction and survival of the earthworm Eisenia fetida (Savigny): Assessing the environmental impact of point-source metal contamination in terrestrial ecosystems

The earthworm Eisenia fetida (Annelida: Oligochaeta) was exposed to a geometric series of concentrations of cadmium, copper, lead and zinc in artificial soil using the OECD recommended protocol. Mortality, growth and cocoon production were measured over 56 days to determine LC50 and EC50 values. No observed effect concentrations (NOECs) were also estimated. Furthermore, the percentage of viable cocoons and number of juveniles emerging per cocoon was recorded. Cocoon production was more sensitive than mortality for all the metals, particularly cadmium and copper for which NOEC reproduction values were an order of magnitude lower than those for NOEC mortality. However, there was no significant effect of metals on the viability of cocoons. The weights of earthworms declined in all treatments (including the controls) during the experiment. This was probably due to the lack of suitable food in the OECD standard soil medium used. It was concluded that future experiments should include animal manure in the test medium. The LC50, EC50 and NOEC values determined in this study were compared with concentrations of metals in soils in the vicinity of a smelting works at Avonmouth, southwest England. The 14-day LC50 for zinc in Eisenia fetida was exceeded in soils covering an area of 75 km2 around the works, compared to 4.2 km2 for copper and 4.7 km2 for lead. Soil values for cadmium did not exceed the LC50 value anywhere in the region. Similar estimates of relative effects on reproduction confirmed that zinc is most likely to be responsible for the absence of earthworms from sites close to the Avonmouth works. However, the OECD standard test overestimated the potential effects of metals on populations, since earthworms can be found as close as 1 km from the smelting works. The discrepancy between test and field observations was probably due to the greater availability of the metals in the artificial soil.     

Phytoremediation potential of Spirulina (Arthrospira) platensis: biosorption and toxicity studies of cadmium

This study examines the possibility of using Spirulina (Arthrospira) platensis TISTR 8217 to remove low concentrations of cadmium (less than 100 mg/l) from wastewater. The cyanobacteria were exposed to six different cadmium concentrations for 96 h, and the growth rate was determined using an optical density at 560 nm. The inhibiting concentration (IC50) was estimated using probit analysis. The IC50 at 24, 48, 72, and 96 h were 13.15, 16.68, 17.28, and 18.35 mg/l Cd, respectively. Cellular damage was studied under a light microscope and a transmission electron microscope. Swollen cells and fragmented filaments were observed. Cell injury increased with increasing concentrations of cadmium. Ultrastructural changes were observed in the algae exposed to cadmium concentrations both close to IC50 (14.68 mg/l) and at IC50 (18.35 mg/l). The alterations induced by cadmium were disintegration and disorganization of thylakoid membranes, presence of large intrathylakoidal space, increase of polyphosphate bodies, and cell lysis. In addition, the cadmium adsorption by algal cells was studied. Environmental factors were found to have an effect on biosorption. The uptake of cadmium was not affected by the temperature of the solution, but the sorption was pH dependent. The optimum pH for biosorption of algal cells was 7. The cadmium uptake process was rapid, with 78% of metal sorption completed within 5 min. The sorption data fit well to the Langmuir isotherm. The maximum adsorption capacity for S. platensis was 98.04 mg Cd per g biomass.     

Lethal toxicity of Lindane on a teleost fish, Anguilla anguilla from Albufera Lake (Spain): hardness and temperature effects

This paper reports the results of toxicity tests conducted using Anguilla anguilla under three different water temperature (15, 22 and 29 degrees C) and two hardness regimes (250 and greater than 600 ppm CaCO3). The 96-h LC50 increased in the experimental medium (p less than 0.05) by an order of magnitude from 0.32 to 0.45 mg/L between 15 and 29 degrees C. However in the natural medium it is similar (p greater than 0.05) (0.54 to 0.55 mg/L) for these same temperatures. The toxicity of Lindane on eels increased when the water hardness decreased. The 24, 48, 72 and 96-h LC50 for this fish in both media is less at 15 degrees C (96-h LC50 = 0.32 and 0.55 mg/L) than at 29 degrees C (96-h LC50 = 0.45 and 0.55 mg/L). These results suggest that the toxicity of Lindane presents a negative temperature coefficient.     

Biochemical effects of clomazone herbicide on piava (Leporinus obtusidens)

This study aims to verify the effects of the clomazone concentration used in rice fields on acetylcholinesterase (AChE), thiobarbituric acid reactive substances (TBARS), protein carbonyl and catalase activity in tissues of piava (Leporinus obtusidens). LC(50)-96h was 5.0 mg L(-1) and the fish were exposed to 1/10 of LC(50)-96 h: 0.5 mg L(-1) of clomazone for 96 and 192h. The same parameters were also assayed after a recovery period of 192 h in clean water. AChE activity was reduced only in the brain and heart of fish exposed for 96 h. AChE activity was decreased in the brain, muscle and heart tissues after 192 h of exposure. After 192 h of recovery period, AChE activity remained diminished in brain and muscle and showed a decrease in eye. However, after 192 h of recovery, AChE activity in heart was recovered. Fish showed increased TBARS levels in brain at all experimental periods. TBARS levels decreased in liver and muscle tissues after 192 h of exposure. The increase in muscle TBARS persisted in fish transferred to clean water. Protein carbonyl in the liver was increased in all periods studied including the recovery period. Catalase activity was reduced during all periods. The present study demonstrates the occurrence of disorders in AChE, TBARS, protein carbonyl and catalase activity in piava. The results also show changes in fish after exposure to an environmentally relevant concentration of clomazone. Most effects observed persisted after the recovery period. Thus, these parameters may be used to monitor clomazone toxicity in fish.     

Thiobencarb toxicity and plasma AChE inhibition in the European eel

The acute toxicity of the herbicide thiobencarb (S-4-chlorobenzyl 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 LC50-96 hr = 0.22 mg/L) during 96 hours in a flow-through system and then an elimination 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 medium free of toxicant recovered its normal value while specific AChE activity remained depressed (< 50%) until five days later.     

Impacts of quicklime (CaO) on the toxicity of copper (CuSO4, 5H2O) to fish and fish food organisms

Static bioassays of 96 h duration were conducted in the laboratory using fry of common carp (Cyprinus carpio), adult tubificid worm (Branchiura sowerbyi) and adult copepod plankton (Cyclops viridis) to determine LC50 values of Cu and CaO to these organisms and effects of interaction between Cu and CaO. Ninety-six hour LC(50) values of Cu to fry of common carp, worm and copepod were found to be 1.40 mgl(-1), 0.08 mgl(-1) and 0.03 mgl(-1) respectively. CaO up to 500 mgl(-1) did not produce any mortality of the fry of common carp up to 96 h. But 96 h LC50 values of CaO to worm and copepod were 83.00 mgl(-1) and 27.80 mgl(-1) respectively. When common carp fry, worm and the copepod were exposed to respective LC50 dose of Cu in presence of varying concentration of CaO, mortality of the organisms significantly reduced and was found inversely correlated with the doses of CaO [y = 48.36-0.807x, r = -0.99 (n = 7) for fish; y = 44.46-0.146x, r = -0.97 (n = 7) for worm; y = 49.46-0.66x, r = -0.99 (n = 7) for the copepod]. The present results indicate that CaO is non-toxic to fish and is capable of reducing the toxicity of Cu to fish while CaO and Cu are antagonistic to each other for the worm and the copepod. Potential of using CaO as antitoxic agent for Cu in water is discussed.     

Investigation of acute toxicity of chlorpyrifos-methyl on Nile tilapia (Oreochromis niloticus L.) larvae

Chlorpyrifos-methyl, a wide-spectrum organophosphorus insecticide and potential toxic pollutant contaminating aquatic ecosystems, was investigated for acute toxicity. Larvae of the freshwater fish Nile tilapia (Oreochromis niloticus L.) were selected for the bioassay experiments. The experiments were repeated three times and the 96 h LC50 was determined for the larvae. The static test method for assessing acute toxicity was used. Water temperature was maintained at 25+/-1 degrees C. In addition, behavioral changes at each chlorpyrifos-methyl concentration were observed for the individual fish. Data obtained from the chlorpyrifos-methyl acute toxicity tests were evaluated using Finney's probit analysis statistical method. The 96 h LC50 value for Nile tilapia larvae was calculated to be 1.57 mg/l.     

Toxicity of the mosquito control insecticide phenothrin to three life stages of the grass shrimp (Palaemonetes pugio)

Phenothrin is a synthetic pyrethroid used as a contact insecticide in mosquito control programs. This study compared the toxicity of phenothrin to adult, larval and embryonic grass shrimp (Palaemonetes pugio) and examined oxidative stress responses in adult and larval grass shrimp. The adult 24-h LC50 was 0.341 μg/L (95 % confidence intervals 0.282-0.412) and the 96-h LC50 was 0.161 μg/L (95 % CI 0.128-0.203 μg/L). The larval 24-h LC50 was 0.50 μg/L (95 % CI 0.441-0.568) and the 96-h LC50 was 0.154 μg/L (95 % CI 0.139-0.170 μg/L). In the presence of sediment, the 24-h LC50 was 6.30 μg/L (95 % CI 5.00-7.44 μg/L) for adults and 0.771 μg/L (95 % CI 0.630-0.944) for larvae. The sublethal biomarkers glutathione and lipid peroxidase (LPx) were examined after 96-h phenothrin exposure at five concentrations, and there were no statistically significant differences in these levels in adults or larvae compared to controls. There was a significant downward trend in larval LPx levels. This research confirms that phenothrin is highly toxic to grass shrimp and suggests that both adult and larval grass shrimp are appropriate life stages for risk assessments.     

A freshwater shrimp (Paratya compressa improvisa) as a sensitive test organism to pesticides

The susceptibility of 2-week-old individuals of the freshwater shrimp, Paratya compressa improvisa, to five kinds of insecticide and five kinds of herbicide was examined in comparison with that of two species of Cladocera, Daphnia magna and Moina macrocopa. The shrimp was especially sensitive to two organophosphorus insecticides. The 48-h LC50 values for fenitrothion and fenthion to the shrimp were 1.15 and 1.04 microg litre(-1) (mean value, n=2), in contrast with 37.8 and 35.3 microg litre(-1) in the case of M. macrocopa, and more than 50 microg litre(-1) with D. magna. The shrimp also showed the higher susceptibility to other insecticides, diazinon, carbaryl (NAC) and BPMC, apart from D. magna to diazinon and NAC. The shrimp also showed higher susceptibility to herbicides. The 48-h LC50 values of CNP, benthiocarb, oxadiazon, butachlor, and symetryne to the shrimp were two to eight times lower than those of two species of Cladocera, except for the LC50 value of oxadiazon to M. macrocopa, which was very slightly higher. However, the shrimp showed a somewhat lower susceptibility to heavy metals than the two species of Cladocera, especially to copper, and to cadmium and zinc in comparison with D. magna. A bioassay using the shrimp with river water, collected from the river adjacent to the paddy field, showed clearly the high mortality of the shrimp following the aerial spraying with pesticides.     

Toxicity of the mosquito control pesticide Scourge to adult and larval grass shrimp (Palaemonetes pugio)

This study investigated the toxicity of various concentrations of technical resmethrin and Scourge on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-h static renewal aqueous test without sediment, and a 24-h static nonrenewal aqueous test with sediment. For resmethrin, the 96-h aqueous LC50 value for adult shrimp was 0.53 microg/L (95% confidence interval (CI): 0.46-0.60 microg/L), and for larval shrimp was 0.35 microg/L (95% CI: 0.28-0.42 microg/L). In the presence of sediment, technical resmethrin produced a 24-h LC50 value for adult shrimp of 5.44 microg/L (95% CI: 4.52-6.55 microg/L), and for larval shrimp of 2.15 microg/L (95% CI: 1.35-3.43 microg/L). For Scourge, the 96-h aqueous LC50 for adult shrimp was 2.08 microg/L (95% CI: 1.70-2.54 microg/L), and for larval shrimp was 0.36 microg/L (95% CI: 0.24-0.55 microg/L). The 24-h sediment test yielded an LC50 value of 16.12 microg/L (95% CI: 14.79-17.57 microg/L) for adult shrimp, and 14.16 microg/L (95% CI: 12.21-16.43 microg/L) for larvae. Adjusted LC50 values to reflect the 18% resmethrin concentration in Scourge are 0.37 microg/L (adult), 0.07 microg/L (larvae) for the 96-h aqueous test, and 2.90 microg/L (adult), 2.6 microg/L (larvae) for the 24-h sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge.     

Mortality response and LC50 values for juvenile and adult crayfish, Procambarus clarkii exposed to Thiodan (insecticide), Treflan, MSMA, Oust (herbicides) and Cutrine-Plus (algicide)

Toxicities of three herbicides (Treflan, MSMA and Oust), an algicide (Cutrine-plus) and an insecticide (Thiodan) to juvenile (3.0-3.4 cm) and adult (9.0-10.0 cm) crayfish, Procambarus clarkii, were determined by 96 h static bioassays. Freshly prepared 0.01% and 1.0% aqueous stock solutions of these pesticides were diluted to desired concentrations. Mortalities were recorded each day up to 96 h. Aged tap-water was used for preparing all test solutions. Per cent mortalities were analyzed for linear regression and LC(50) values were computed by probit analysis. LC(50) values for juvenile P.clarkii in the descending order of toxicity were: 24 ppb Thiodan, 13 ppm Treflan, 101 ppm MSMA, 461 ppm Cutrine-plus, 12,174 ppm Oust; and for adults these values were: 423 ppb Thiodan, 26 ppm Treflan, 1019 ppm MSMA and 2945 ppm Cutrine-plus. No LC(50) values for adult crayfish could be computed for Oust herbicide which caused no mortalities up to 60,000 ppm concentration. Comparing the overall toxicities of these pesticides, Thiodan was the most toxic to all crayfish; followed by Treflan, MSMA, Cutrine-plus and Oust. Oust was more than 1/2 million times less toxic than Thiodan to juvenile crayfish. Published LC(50) values indicate that freshwater crayfish are more tolerant than marine decapods, Crangon septemspinosa and Mysidopsis bahia, to Thiodan insecticide and Treflan herbicide.     

Toxicity of the mosquito control insecticide phenothrin to three life stages of the grass shrimp (Palaemonetes pugio)

Phenothrin is a synthetic pyrethroid used as a contact insecticide in mosquito control programs. This study compared the toxicity of phenothrin to adult, larval and embryonic grass shrimp (Palaemonetes pugio) and examined oxidative stress responses in adult and larval grass shrimp. The adult 24-h LC50 was 0.341 μg/L (95 % confidence intervals 0.282–0.412) and the 96-h LC50 was 0.161 μg/L (95 % CI 0.128–0.203 μg/L). The larval 24-h LC50 was 0.50 μg/L (95 % CI 0.441–0.568) and the 96-h LC50 was 0.154 μg/L (95 % CI 0.139–0.170 μg/L). In the presence of sediment, the 24-h LC50 was 6.30 μg/L (95 % CI 5.00–7.44 μg/L) for adults and 0.771 μg/L (95 % CI 0.630–0.944) for larvae. The sublethal biomarkers glutathione and lipid peroxidase (LPx) were examined after 96-h phenothrin exposure at five concentrations, and there were no statistically significant differences in these levels in adults or larvae compared to controls. There was a significant downward trend in larval LPx levels. This research confirms that phenothrin is highly toxic to grass shrimp and suggests that both adult and larval grass shrimp are appropriate life stages for risk assessments.