Acute Toxicity and Effects Analysis of Endosulfan Sulfate to Freshwater Fish Species

Endosulfan sulfate is a persistent environmental metabolite of endosulfan, an organochlorine insecticide–acaricide presently registered by the United States Environmental Protection Agency. There is, however, limited acute fish toxicity data for endosulfan sulfate. This study determines the acute toxicity (LC₅₀s and LC₁₀s) of endosulfan sulfate to three inland Florida native fish species (mosquitofish [Gambusia affinis]; least killifish [Heterandria formosa]; and sailfin mollies [Poecilia latipinna]) as well as fathead minnows (Pimephales promelas). Ninety-six-h acute toxicity tests were conducted with each fish species under flow-through conditions. For all of the above-mentioned fish species, 96-h LC₅₀ estimates ranged from 2.1 to 3.5 μg/L endosulfan sulfate. The 96-h LC₁₀ estimates ranged from 0.8 to 2.1 μg/L endosulfan sulfate. Of all of the fish tested, the least killifish appeared to be the most sensitive to endosulfan sulfate exposure. The above-mentioned data were combined with previous acute toxicity data for endosulfan sulfate and freshwater fish for an effects analysis. The effects analysis estimated hazardous concentrations expected to exceed 5, 10, and 50% of the fish species’ acute LC₅₀ or LC₁₀ values (HC₅, HC₁₀, and HC₅₀). The endosulfan sulfate freshwater-fish acute tests were also compared with the available freshwater-fish acute toxicity data for technical endosulfan. Technical endosulfan is a mixture of α- and β-endosulfan. The LC₅₀s had a wider range for technical endosulfan, and their distribution produced a lower HC₁₀ than for endosulfan sulfate. The number of freshwater-fish LC₅₀s for endosulfan sulfate is much smaller than the number available for technical endosulfan, reflecting priorities in examining the toxicity of the parent compounds of pesticides. The toxicity test results and effects analyses provided acute effect values for endosulfan sulfate and freshwater fish that might be applied in future screening level ecologic risk assessments. The effects analyses also discussed several deficiencies in conventional methods for setting water-quality criteria and determining ecologic effects from acute toxicity tests.     

Ecotoxicological Assessment of Cobalt Used as Supplement in the Diet of Common Carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis>

Experiments were performed in the laboratory to determine if excess levels of Co used as dietary supplement (0.0, 0.05, 0.10 and 1.0%) to enhance growth of the fish Cyprinus carpio was safe for aquatic organisms. Lethal concentrations of Co for tadpole of toad Bufo melanostictus (96 h LC₅₀, 17.2 mg/L), oligochaet worm Branchiura sowerbyi (96 h LC₅₀, 179 mg/L) and crustacean zooplankton Diaptomus forbesi (96 h LC₅₀, 1.5 mg/L) were compared with the concentration of Co in the medium leached from the unused diets and faeces. The results indicated that the Co leached from diet containing 1.0% Co was ecotoxicologically unsafe for crustacean zooplankton.     

Effects of the Veterinary Pharmaceutical Ivermectin on Soil Invertebrates in Laboratory Tests

As part of the risk assessment of veterinary pharmaceuticals, the potential impact of these chemicals on soil ecosystems has to be determined according to European law. However, almost no data from standardized laboratory tests are available. Therefore, in the EU FP6 ERAPharm, the effects of the widely used veterinary pharmaceutical ivermectin, an anthelminthic, were studied in chronic laboratory tests performed according to OECD (Organisation for Economic Co-operation and Development) and ISO (International Organization for Standardization) guidelines. In detail, three soil invertebrate species—the earthworm Eisenia fetida, the springtail Folsomia candida, and the predatory mite Hypoaspis aculeifer—were tested. The nominal concentrations of ivermectin mixed into the test substrate artificial soil was verified using residue analysis, which indicated that the test substance is persistent for at least up to 28 days. As expected when considering the mode of action of this substance, survival and reproduction of collembolans were clearly affected [LC₅₀ = 8.4 mg/kg soil dry weight (dw); NOEC_repro = 0.3 mg/kg soil (dw)]. Predatory mites reacted less sensitively [LC₅₀ ≥ 31.6 mg/kg soil (dw); NOEC_repro = 3.2 mg/kg soil (dw)]. Earthworm survival and reproduction were affected in the same order of magnitude as the predatory mites [LC₅₀ ≥ 10 mg/kg soil (dw); NOEC_repro = 2.5 mg/kg soil (dw)]. These results are in good agreement with the few data known from nonstandardized tests for the same or related soil invertebrate species. The results of these tests indicate that the effects of ivermectin on soil invertebrates—in particular, collembolans—cannot be excluded at field-relevant concentrations, as determined in a risk assessment according to VICH guidelines. More sophisticated higher-tier tests (e.g., in multispecies or semifield test systems) are recommended in order to assess the potential risk more accurately.     

Mortality and Abnormalities Observed After Experimental Hg Exposure in the Polychaete <Emphasis Type="Italic">Eurythoe complanata</Emphasis> (Pallas) from Mazatlan,Mexico

Lethal effects of Hg on Eurythoe complanata held under laboratory conditions were evaluated (LC₅₀ and LT₅₀). Worms were exposed to 0–900 μg/L of Hg for 10 days. Mortality occurred in all the treatments, being faster at 200–900 μg/L, which was confirmed by a Friedman ANOVA non-parametric test. The 4-day LC₅₀ = 197.15 μg/L (200 μg/L LT₅₀ = 3.4 days) was similar to that reported for other Hg tolerant annelids. Abnormalities were observed in worms exposed to all the treatments, becoming more severe as Hg concentrations increased: body darkening, rough, white and opaque skin, everted and swollen proboscis and gut evisceration.     

Toxicity of Sediment-Associated Pesticides to <Emphasis Type="Italic">Chironomus dilutus</Emphasis> and <Emphasis Type="Italic">Hyalella azteca</Emphasis>

Two hundred sediment samples were collected and their toxicity evaluated to aquatic species in a previous study in the agriculturally dominated Central Valley of California, United States. Pyrethroid insecticides were the main contributors to the observed toxicity. However, mortality in approximately one third of the toxic samples could not be explained solely by the presence of pyrethroids in the matrices. Hundreds of pesticides are currently used in the Central Valley of California, but only a few dozen are analyzed in standard environmental monitoring. A significant amount of unexplained sediment toxicity may be due to pesticides that are in widespread use that but have not been routinely monitored in the environment, and even if some of them were, the concentrations harmful to aquatic organisms are unknown. In this study, toxicity thresholds for nine sediment-associated pesticides including abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin were established for two aquatic species, the midge Chironomus dilutus and the amphipod Hyalella azteca. For midges, the median lethal concentration (LC₅₀) of the pesticides ranged from 0.18 to 964 μg/g organic carbon (OC), with abamectin being the most toxic and propargite being the least toxic pesticide. A sublethal growth endpoint using average individual ash-free dry mass was also measured for the midges. The no–observable effect concentration values for growth ranged from 0.10 to 633 μg/g OC for the nine pesticides. For the amphipods, fenpropathrin was the most toxic, with an LC₅₀ of 1–2 μg/g OC. Abamectin, diazinon, and methyl parathion were all moderately toxic (LC₅₀s 2.8–26 μg/g OC). Dicofol, indoxacarb, oxyfluorfen, propargite, and pyraclostrobin were all relatively nontoxic, with LC₅₀s greater than the highest concentrations tested. The toxicity information collected in the present study will be helpful in decreasing the frequency of unexplained sediment toxicity in agricultural waterways.     

The Effect of some Selected Pesticides on the Growth and Reproduction of Fresh Water <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>, <Emphasis Type="Italic">Chrysicthys nigrodigitatus</Emphasis> and <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

Studies were carried out to determine the toxicity of some selected pesticides on fresh water fish in a tropical environment. The uptake of the pesticides lindane, pentachlorophenol (PCP), and propoxur, which are frequently used on farms, and in industries as well as by loggers and timber men on wood were studied in concrete ponds at the University of Cape Coast, in Ghana. The fish used for the study were Oreochromis niloticus, Clarias gariepinus, and Chrysicthys nigrodigitatus. They were obtained from cultured ponds in the Cape Coast and Mankessim districts in the Central Region and Weija Dam, in the Greater Accra region of Ghana. Single high lethal concentration (SD) or acute treatment and cumulative/chronic (or multiple minor) lethal concentration (CD) treatment were employed in administering the pesticides to the fish via water. Gas chromatograph electron capture detector analysis was done on the dead fish to see the extent of ingestion. The LC₅₀ values obtained for lindane on the three fish samples were as follows: Chrysicthys – 0.38 mg L⁻¹; Oreochromis – 0.42 mg L⁻¹, and Clarias – 1.2 mg L⁻¹. Mortalities occurred in fish within 3–5 days of application. For the PCP on Chrysicthys, Oreochromis, and Clarias species the LC₅₀ values were 0.42, 0.32 and 0.64 mg L⁻¹, respectively, for over a 2- to 3-day period. For a three-time influx period of propoxur the LC₅₀ for Chrysicthys, Oreochromis, and Clarias, were 22.0, 30.40, and 45.04 (all in mg L⁻¹), respectively. The results obtained indicated that the pesticides had adverse effects on the general growth and reproduction of fish as shown by gonadosomatic indices.     

Teratogenic effects of amitraz, 2,4-dimethylaniline,and paraquat on developing frog (Xenopus) embryos

Developmental effects of amitraz (acaricide), its metabolite (2,4-dimethylaniline), and paraquat (herbicide) on embryos of a nontarget organism, Xenopus laevis, were investigated. Following the standard protocol of the American Society for Testing and Materials (ASTM), the experiments were carried out using native Xenopus frogs. There was a drastic increase in mortality from 24 h to 96 h for paraquat, but 2,4-dimethylaniline showed no mortality at the highest concentration tested (100 mg/L). The 96-h LC₅₀ values were 0.67, 3.27, and ≫100 mg/L for paraquat, amitraz, and 2,4-dimethylaniline, respectively. At concentrations higher than 0.2 mg/L of paraquat all the embryos were malformed, whereas growth reduction was apparent at all test concentrations (0.1–5 mg/L). The most common teratogenic effects were flexures of the notochord and stunting of growth. Edema was the most common effect of amitraz on the embryos, and 100% of the surviving embryos in 5 mg/L were edematous. The 96-h EC₅₀ (malformation) values were 1.21 (95% CI 0.48–3.03) and 0.18 (95% CI 0.16–0.20) mg/L for amitraz and paraquat, respectively. The ratio of 96-h LC₅₀ to 96-h EC₅₀ (malformation), i.e., the teratogenicity index (TI) were 2.7 and 3.72 for amitraz and paraquat, respectively, and for 2,4-dimethylaniline (TI > 5) all the embryos in 25 mg/L showed observable pigment loss and encephalomegaly. This shows that paraquat and the degradation product of amitraz, 2,4-dimethylaniline, should be classified as teratogens. Teratogenic risks of massive application of these pesticides on Kenyan farms should therefore be considered. Received: 27 June 2001/Accepted: 4 February 2002     

Assessment of the Genotoxicity of Endosulfan in Earthworm and White Clover Plants Using the Comet Assay

Endosulfan, as one of the most widely used organochlorine pesticides in the world, has increased the public concern about genotoxicity in soil ecosystems. The comet assay has been widely used in the fields of genetic toxicology and environmental biomonitoring. In the present study we conducted comet assay of endosulfan in earthworm (Eisenia foetida) and white clover (Trifolium repens L.), which are sensitive organisms suitable for acting as a bioindicator for agricultural ecosystems. Earthworms were exposed to endosulfan concentrations of 0.1, 1.0, and 10.0 mg/kg in the soil. White clover roots were immersed in hydroponic pots containing nutrient solutions of different endosulfan concentrations: 0.1, 1.0, and 10.0 mg/L. Tissues from each treatment were collected on the 7th, 14th, 21st, and 28th days of treatment process. Significant effects (p < 0.01) of both concentrations and times of exposure were observed. And endosulfan induced DNA damage in earthworm and white clover nuclei. The comet assay can be used as a reliable tool for early detection of endosulfan.     

Toxicity and physiological effects of neem pesticides applied to rice on the Nilaparvata lugens Stål, the brown planthopper

The effects of two different neem products (Parker Oil™ and Neema^®) on mortality, food consumption and survival of the brown planthopper, Nilaparvata lugens Stål (BPH) (Homoptera: Delphacidae) were investigated. The LC₅₀ (3.45 ml/L for nymph and 4.42 ml/L for adult in Parker Oil™ treatment; 4.18 ml/L for nymph and 5.63 ml/L for adult in Neema^® treatment) and LC₉₀ (8.72 ml/L for nymph and 11.1 ml/L for adult in Parker Oil™ treatment; 9.84 ml/L for nymph and 13.07 ml/L for adult in Neema^® treatment) were identified by probit analysis. The LC₉₀ (equal to recommended dose) was applied in the rice field. The effective concentration of both Parker Oil™ and Neema^® took more than 48 h to kill 80% of the N. lugens. Fourth instar nymph and adult female N. lugens were caged on rice plants and exposed to a series (both LC₅₀ and LC₉₀) of neem concentrations. Nymph and adult female N. lugens that were chronically exposed to neem pesticides showed immediate mortality after application in laboratory experiment. The quantity of food ingested and assimilated by N. lugens on neem-treated rice plants was significantly less than on control rice plants. The results clearly indicate the neem-based pesticide (Parker Oil™ and Neema^®), containing low lethal concentration, can be used effectively to inhibit the growth and survival of N. lugens.     

Monitoring of Residual Pesticides in Herbal Drug Materials of Korea and China

The information of the pesticide residues in herbal drug materials (HDMs) is not sufficient to support the scientific risk management so far. Therefore, 30 types of HDMs such as the herba of Artemisia montana were analyzed for 47 different pesticides. Among 292 samples, eight Chinese and one Korean HDMs were contaminated with five pesticides such as methoxychlor, DDT, γ-BHC, endosulfan, and procymidone (0.044–0.501 mg/kg). The detection rate of pesticides in the tested HDMs was determined as 3.1%. On critical observation of the detected amount of procymidone (0.501 mg/kg) and methoxychlor (0.382 and 0.312 mg/kg), further intensive monitoring of the pesticides might be necessary for HDMs.     

In vivo andIn vitro studies on synergism with anticholinesterase pesticides in the snailLymnaea acuminata

The synergistic effects of piperonyl butoxide (PB)², sulfoxide (SU), and dimethyl amino aniline (DAA) used in conjunction with two organophosphate pesticides (phorate and formothion) and two carbamate pesticides (mexacarbate and carbaryl) were examined in terms of the LC₅₀ and acetylcholinesterase (AChE) inhibition in the snailLymnaea acuminata. The three synergists reduced the LC₅₀ of phorate, formothion, mexacarbate, and carbaryl at exposure periods ranging from 24 to 144 hr. PB and SU had strong synergistic action; DAA had little effect; the highest synergistic ratio (70) was found with carbaryl and PB. The synergists enhanced thein vitro inhibition of cholinesterase caused by the pesticides; the synergistic effect onin vitro inhibition, however, was lower, compared to the change in the LC₅₀.     

Lethal and Sublethal Toxicity of the Antifoulant Compound Irgarol 1051 to the Mud Snail <Emphasis Type="Italic">Ilyanassa obsoleta</Emphasis>

Irgarol 1051 is an algistatic compound used in copper-based antifoulant paints. It is a widespread and persistent pollutant of the estuarine environment. Ilyanassa obsoleta, the Eastern mud snail, is a common intertidal gastropod that inhabits mud flats and salt marshes along the east coast of North America. It is an important inhabitant of the estuarine environment; contributing to nutrient regeneration and regulating microbial processes in the sediments. The toxicity of irgarol to estuarine gastropods has not been previously examined, although they have the potential to be exposed to antifoulants through both aqueous and sediment routes. The objectives of this study were to evaluate irgarol’s effects on I. obsoleta survival, reproductive status (imposex occurrence and testosterone levels), chemoreceptive function, and cellular respiration (cytochrome-c oxidase activity). Irgarol was moderately toxic to I. obsoleta; adult aqueous 96-h LC₅₀ = 3.73 mg/L, larval aqueous 96-h LC₅₀ = 3.16 mg/L, and adult sediment 10-day LC₅₀ = 12.21 mg/kg. Larval snails were not significantly more sensitive to irgarol than adult snails. A chronic 45-day aqueous irgarol exposure (0.005–2.5 mg/L) did not induce imposex or affect free-testosterone levels. The 45-day chronic LC₅₀ of 1.88 mg/L was significantly lower than the 96-h acute value. A 96-h acute aqueous irgarol exposure (0.375–1.5 mg/L) caused a decrease in normal response to chemosensory cues such as the presence of food or predators. There was a significant increase in cytochrome-c oxidase activity at 2.5 mg/L, which might indicate irgarol’s disruption of the mitochondrial membrane and subsequently ATP synthesis. Although the toxicity values determined for I. obsoleta exceeded irgarol concentrations measured in surface waters, results from this toxicity assessment will provide valuable information to environmental resource managers faced with decisions regarding the use and regulation of antifoulant paints in the coastal zone.     

Toxicity of Four Herbicide Formulations with Glyphosate on <Emphasis Type="Italic">Rhinella arenarum</Emphasis> (Anura: Bufonidae) Tadpoles: B-esterases and Glutathione <Emphasis Type="Italic">S</Emphasis>-transferase Inhibitors

In this study, amphibian tadpoles Rhinella arenarum were exposed to different concentrations of Roundup Ultra-Max (ULT), Infosato (INF), Glifoglex, and C-K YUYOS FAV. Tadpoles were exposed to these commercial formulations with glyphosate (CF-GLY) at the following concentrations (acid equivalent [ae]): 0 (control), 1.85, 3.75, 7.5, 15, 30, 60, 120, and 240 mg ae/L for 6–48 h (short-term). Acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferase (GST) activities were measured among tadpoles sampled from those treatments that displayed survival rates >85%. Forty-eight-hour LC₅₀ for R. arenarum tadpoles exposed to CF-GLY in the static tests ranged from ULT = 2.42 to FAV = 77.52 mg ae/L. For all CF-GLY, the LC₅₀ values stabilized at 24 h of exposure. Tadpoles exposed to all CF-GLY concentrations at 48 h showed decreases in the activities of AChE (control = 17.50 ± 2.23 nmol/min/mg/protein; maximum inhibition INF 30 mg ae/L, 71.52%), BChE (control = 6.31 ± 0.86 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 78.84%), CbE (control = 4.39 ± 0.46 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 81.18%), and GST (control = 4.86 ± 0.49 nmol/min/mg/protein; maximum inhibition INF 1.87 mg ae/L, 86.12%). These results indicate that CF-GLY produce a wide range of toxicities and that all enzymatic parameters tested may be good early indicators of herbicide contamination in R. arenarum tadpoles.     

Toxicity and Bioconcentration Potential of the Agricultural Pesticide Endosulfan in Phytoplankton and Zooplankton

Agricultural pesticide runoff in southeastern coastal regions of the United States is a critical issue. Bioconcentration of pesticides by phytoplankton and zooplankton at the base of the aquatic food web may increase the persistence of pesticides in aquatic ecosystems and cause effects at higher trophic levels. This study examined the toxicity of a widely used agricultural pesticide, endosulfan, to Pseudokirchneriella subcapitatum (freshwater green alga) and Daphnia magna (freshwater cladoceran). We then investigated the potential of both plankton species to sequester endosulfan from their surrounding media. We also assessed the degree to which endosulfan is accumulated by D. magna via food (endosulfan-contaminated P. subcapitatum). A 96-h growth rate EC₅₀ of 427.80 μg/L endosulfan was determined for P. subcapitatum, whereas a 24-h immobilization EC₅₀ of 366.33 μg/L endosulfan was determined for D. magna. The 5-h EC₅₀s for filtration and ingestion in D. magna were 165.57 μg/L and 166.44 μg/L, respectively. An average bioconcentration factor (BCF) of 2,682 was determined for P. subcapitatum exposed to 100 μg/L endosulfan for 16 h. An average BCF of 3,278 was determined for D. magna in a 100 μg/L endosulfan water-only exposure. There was negligible uptake of endosulfan by D. magna feeding on contaminated algae in clean water (BCF ∼ 0). Different proportions of parent isomers (endosulfan I and II) and the primary degradation product (endosulfan sulfate) were detected among treatments. Endosulfan was rapidly accumulated and concentrated from water by P. subcapitatum and D. magna neonates. Endosulfan contained in phytoplankton, however, was not bioaccumulated by zooplankton. These findings may prove useful in assessing ecosystem risk, because uptake from the water column appears to be the dominant route for bioconcentration of endosulfan by zooplankton. Received: 30 January 2001/Accepted: 26 August 2001     

Comparison of Diazinon Toxicity to Embryos of <Emphasis Type="Italic">Xenopus laevis</Emphasis> and <Emphasis Type="Italic">Danio rerio</Emphasis>; Degradation of Diazinon in Water

The aim of this study was to determine the toxic effect of diazinon (organophosphate insecticide) to embryos of Xenopus laevis and Danio rerio. The 96-h LC₅₀ values showed higher toxicity of diazinon for X. leavis in standard solution (9.84 mg/L) compared to the pond water (12.64 mg/L). Teratogenic index for diazinon was 1.3 and 1.6, respectively. The 96-h LC₅₀ diazinon values demonstrated similar sensitivity of embryos D. rerio (8.21–9.34 mg/L) and X. laevis in standard test solutions. Our results reflect that direct application of diazinon into the water can be associated with significant risks to aquatic organisms.     

Acute and chronic effects of carbaryl on survival,growth, and metamorphosis in the bullfrog (Rana tigrina)

The effects of carbaryl (1-naphthalenyl methylcarbamate), an extensively used insecticide in agricultural operations, have been studied on survival, growth, and metamorphosis of the bullfrog tadpoleRana tigrina. The 96 hr LC₅₀ value for tadpoles (0.02 g) was 6.2 mg/L. The tadpoles were reared from hatching to metamorphosis in sublethal concentrations of carbaryl. Rates of feeding, defecation, and excretion increased with increasing concentration of carbaryl but the conversion rate decreased leading to the production of small froglets. The tadpoles exposed to the sublethal concentrations suffered no mortality until the appearance of the forelimb; however, during metamorphosis mortality was significant, even at 2 mg/L.     

Toxic and sublethal effects of carbaryl on a freshwater catfish,Mystus vittatus (Bloch)

The effects of carbaryl (1-naphthalenyl methylcarbamate), commonly used in agricultural operations, have been studied with reference to survival, behavior, food intake, growth, and conversion efficiency of the catfishMystus vittatus. At a concentration of 32.5 ppm, carbaryl caused 100% mortality within 24 hr; the 72 hr LC₅₀ was 17.5 ppm. At concentrations of 12.5 ppm and below, it caused no mortalities within 72 hr. But such sublethal concentrations accelerated the swimming activity and increased the frequency of opercular beats. The latter response was dose-dependent. These behavioral changes were the immediate response to the toxicant and were indicators of possible stress. A 27-day exposure to sublethal concentrations of carbaryl led to a decrease in feeding rate and growth rate. The latter decreased from 10.15 mg/g/day (freshwater) to 2.84 mg/g/day (12.5 ppm). The reduced growth and conversion efficiency may be due to the expenditure of more energy for the purpose of maintenance. Therefore, the insecticide is considered to be a metabolic Stressor.     

Effect of Yerbimat Herbicide on Lipid Peroxidation,Catalase Activity,and Histological Damage in Gills and Liver of the Freshwater Fish <Emphasis Type="Italic">Goodea Atripinnis</Emphasis>

The use of herbicides for agricultural and aquatic weed control has increased worldwide. These substances are potentially toxic pollutants because they induce the production of reactive oxygen species for biological systems and exert oxidative stress in nontarget organisms living in the treated aquatic systems. Recent evidence suggests differences in the toxicity of glyphosate in the form of an active ingredient compared to the toxicity of glyphosate in combination with surfactants, such as those found in commercial formulations. In Mexico, one of the most widely used glyphosate-based herbicides is Yerbimat, which has agricultural as well as aquatic weed control applications. However, there are no aquatic toxicity data, particularly regarding native fish. Therefore, we determined the acute toxicity of commercial-formulation Yerbimat in a static bioassay at 96 h (LC₅₀). We also determined its toxicity at 96 h in sublethal concentrations to assess the lipid peroxidation levels (LPX), catalase activity, hepatic glycogen content, and histological damage in the liver and gills of the fish Goodea atripinnis associated with chronic exposure (75 days). The LC₅₀ was 38.95 ± 0.33 mg/L. The results of the short-term exposure study indicate that Yerbimat can potentially induce oxidative stress in G. atripinnis, because LPX was increased in the gills and liver. Catalase activity was reduced in the gills but increased in the liver, whereas hepatic glycogen was depleted. Chronic exposure was associated with histopathological damage in the gills and liver, some of which was irreversible. Yerbimat represents a potential risk for aquatic biota; therefore, we recommend that its application be carefully considered.     

The Toxicity of Glyphosate and Several Glyphosate Formulations to Four Species of Southwestern Australian Frogs

The acute toxicity of technical-grade glyphosate acid, glyphosate isopropylamine, and three glyphosate formulations was determined for adults of one species and tadpoles of four species of southwestern Australian frogs in 48-h static/renewal tests. The 48-h LC₅₀ values for Roundup? Herbicide (MON 2139) tested against tadpoles of Crinia insignifera, Heleioporus eyrei, Limnodynastes dorsalis, and Litoria moorei ranged between 8.1 and 32.2 mg/L (2.9 and 11.6 mg/L glyphosate acid equivalent [AE]), while the 48-h LC₅₀ values for Roundup? Herbicide tested against adult and newly metamorphosed C. insignifera ranged from 137–144 mg/L (49.4–51.8 mg/L AE). Touchdown? Herbicide (4 LC-E) tested against tadpoles of C. insignifera, H. eyrei, L. dorsalis, and L. moorei was slightly less toxic than Roundup? with 48-h LC₅₀ values ranging between 27.3 and 48.7 mg/L (9.0 and 16.1 mg/L AE). Roundup? Biactive (MON 77920) was practically nontoxic to tadpoles of the same four species producing 48-h LC₅₀ values of 911 mg/L (328 mg/L AE) for L. moorei and >1,000 mg/L (>360mg/L AE) for C. insignifera, H. eyrei, and L. dorsalis. Glyphosate isopropylamine was practically nontoxic, producing no mortality among tadpoles of any of the four species over 48 h, at concentrations between 503 and 684 mg/L (343 and 466 mg/L AE). The toxicity of technical-grade glyphosate acid (48-h LC₅₀, 81.2–121 mg/L) is likely to be due to acid intolerance. Slight differences in species sensitivity were evident, with L. moorei tadpoles showing greater sensitivity than tadpoles of the other four species. Adult and newly emergent metamorphs were less sensitive than tadpoles. Received: 19 February 1998/Accepted: 16 August 1998     

Preliminary Evaluation of The Acute Toxicity of Cypermethrin and λ-Cyhalothrin to <Emphasis Type="Italic">Channa Punctatus</Emphasis>

In the present study, the acute toxicity of the pyrethroid pesticides, cypermethrin and λ-cyhalothrin was conducted for a 96 h period using Channa punctatus. The LC₅₀ values of cypermethrin and λ-cyhalothrin were found to be 0.4 mg/L and 7.92 μg/L, respectively. The λ-cyhalothrin was found to be about 50 times more toxic to the fish than cypermethrin. The behavioral pattern of C. punctatus got severely altered in each group due to pesticide treatment. The results suggested that even at low concentrations, these pyrethroid compounds may exert toxic effects, markedly modifying their behavioral pattern.