Differential toxic response of Chironomus travalensis kieffer ( Chironomidae : Diptera ) to some industrial effluents

Acute toxicity testing of some industrial effluents (rubber (Rr), brewery (Br), and bottling (Bt)) on Chironomus travalensis (Diptera larvae) was determined at 96-h using a static bioassay technique. Effluent quality characterization revealed acidic pH values of 4.5 for Rr, 5.64 for Br, and 4.32 for Bt effluents. Tests were carried out in replicates between 10 and 100% effluent concentrations. Mortality rate rose progressively with increasing concentrations. Bt effluent was the most toxic with 96-h LC₅₀ of 61.5%, closely followed by Rr effluent with 96-h LC₅₀ of 87% and the least toxic was Br effluent with 96-h LC₅₀ of 90%.     

Monitoring toxicity of an azo dye methyl red and a heavy metal Cu,using plant and animal bioassays

Toxicities of an azo dye methyl red and a heavy metal copper (Cu) were quantified, using growth and mortality as end points, in four plant species and three animal species by subjecting them to short-term (4 days for animals, 10 days for plants) static bioassays. Lemna aequinoctialis Welwitch (EC₅₀: 7–16 ppm) was found to be the most sensitive species for methyl red, Ceratophyllum demersum L. (EC₅₀: 25 ppm) and Lactuca sativa L. (EC₅₀: 56 ppm) were intermediate, while Oryza sativa L. shows reduction in seedling vigor (9–27%) of <50%, being the least sensitive amongst the tested plant species. Methyl red toxicity is almost 3–5-fold higher in growing medium (pH = 5.8–6.0), even at high nutrient levels, while Cu toxicity is higher in nutrient-poor alkaline medium at alkaline pH (8.3–8.7; EC₅₀: Ceratophyllum = 104–200 ppb; Lemna = 100–170 ppb) compared to nutrient-rich acidic medium (pH = 5.4–5.7; EC₅₀: Ceratophyllum = 2600–3175 ppb; Lemna = 4350–4715 ppb). Rice tolerance (EC₅₀: 6500 ppb) was found to be higher than hydrophytes while lettuce was most tolerant to Cu. Fish sensitivity toward the test chemicals was almost parallel to Ceratophyllum and Lemna [Gambusia affinis Baird and Gerard (LC₅₀: 250 ppb for Cu) and Poecilia reticulata Peters (LC₅₀: 24 ppm for methyl red)]. Similar to the plants, dye toxicity increased markedly (LC₅₀: 7 ppm) in the acidic medium (pH = 6.0). Amongst the tested organisms, Daphnia was found to be most sensitive to methyl red (EC₅₀: 6 ppm) while its sensitivity to Cu (EC₅₀: 230 ppb) was similar to hydrophytes and fish. Initially, the combination of dye and Cu (at their sublethal concentrations) had additive effects in duckweed, while dye concentration ruled afterward. These results indicate that hydrophytes and animals are equally sensitive toward the test chemicals. Dye toxicity in hydrophytes and fish was pH dependent, while in the case of Cu, it is related to the nutrient status of the growth medium of plants.     

Survival and chloride ion regulation of the porcelain crab Petrolisthes armatus exposed to mercury

Acute toxicity bioassays conducted at various salinities demonstrated that mercury (as mercuric chloride) at low concentrations was lethal to Petrolisthes armatus. Ninety-six hour LC₅₀ values varied from 50 to 64 parts per billion (ppb) of mercury, depending on test salinities. Lower salinities. decreased the time to death of mercuryexposed crabs. Differences in survival after 96 h due to salinity were not statistically significant. Blood chloride concentrations were regulated hyperchloride to the medium at low salinities and hypochloride at high salinities by acclimated crabs. The salinity isochloride to blood was 20 S. Transfer of crabs from 15 S to salinities ranging from 7 to 35 S resulted in new steadystate chloride levels within 12 h. Exposure to 50 ppb mercury did not alter chloride ion regulation of either acclimated crabs or crabs adjusting to new salinities.     

Acute toxicity of the synthetic pyrethroid pesticide fenvalerate to some air breathing fishes

Lethal concentrations (LC₅₀) of a synthetic pyrethroid pesticide, fenvalerate, for three species of air breathing fish Clarias batrachus, Channa punctatus and Heteropneustes fossilis were determined under water and acetone soluble condition in the laboratory using the static bioassay procedure of the American Public Health Association (APHA,1995). Acetone soluble fenvalerate was found more toxic than the water-soluble fenvalerate irrespective of species and exposure periods. The LC₅₀ value upon 96 days exposure to acetone soluble fenvalerate for C. batrachus, Channa C. punctatus and Heteropneustes H. fossilis were 1.35, 1.0 and 0.65?µg?L^?1, respectively. It is concluded from the present study that fenvalerate is highly toxic even to the hardy air breathing fishes and the pesticide, when dissolved in water, remains photostable and active to render toxicity for long duration.     

The distribution,metabolism and toxicity of 14c-DDT in model aquarium tanks with fish and sediment simulating a tropical marine environment

Studies conducted on the distribution, fate and metabolism of DDT in a model ecosystem simulating a tropical marine environment of fish, Gobious nudiceps, Lethrinus harak, Gobious keinesis, Gobious nebulosis and white shrimp (Panaeus setiferus), show that DDT concentration in the water decreases rapidly within the first 24?h. Rapid accumulation of the pesticide in the biota also reaches a maximum level in 24?h before gradually declining. The bioaccumulation factors calculated for the fish species (G. keinesis) and white shrimp (P. Setiferus) were 270 and 351, respectively, after 24?h. There was a steady build up of DDT residues in the sediment during the first 24?h which continued to a maximum concentration of 6.66?ng/g in the seawater/fish/sediment ecosystem after 3 weeks and 5.27?ng/g in the seawater/shrimps/sediment ecosystem after 2.7 days. The depuration of the accumulated pesticide was slow with only 54% lost in G. nudiceps within 3 days of exposure in fresh sea water. By contrast, depuration was fast in the white shrimp, which lost 97% of the accumulated pesticide under the same conditions. DDT was found to be toxic to two of the fish species (G. nebulosis and L. harak) and to white shrimp, and the degree of toxicity was dependent on the particular species. The 24?h LC₅₀ at room temperature for the fish species G. nebulosis and white shrimp was found to be 0.011 and 0.116?mg/kg, respectively. These levels are comparable to the ones recorded for the temperate organisms. Degradation of DDT to its primary metabolites, DDE and DDD, was found in all the compartments of the ecosystem with DDE being the major metabolite in the fish, shrimps and sediment, while in seawater, DDD dominated as the major metabolite.     

Accumulation and elimination of cadmium and lead in juvenile milkfish during sublethal exposure

Pollution of aquatic environments by trace metals is a worldwide environmental problem. Metal pollutants are increasingly being released into the environment as a result of industrialization. In this study, the bioaccumulation of cadmium and lead in young juvenile milkfish liver (Chanos chanos) was investigated after exposure to three sublethal concentration of each pollutants (1/20, 1/10, and 1/5 LC₅₀ of 96-h LC₅₀) for acute time 12, 24, and 96 h and subchronically for 7, 14, and 21 days. Cadmium and lead accumulation in liver increased with the exposure period and concentrations of pollutant. Compared to controls, the uptake of cadmium is much higher than that of lead. Accumulation factors showed an increase with exposure time and for lead an inverse relationship between accumulation factor and exposure concentration. The elimination of the two pollutants during the 30 days depuration was investigated after 30 days depuration time. During this phase, cadmium and lead concentrations decreased.     

Acute toxicity of ammonia to a freshwater teleost,Labeo bata larvae

Ammonia toxicity tests were performed with Labeo bata (bata) larvae of three different size groups. One hundred percent survival of larvae (500.0?±?4.0?mg) was recorded when exposed to ammonia concentrations of 1.0–13.56?mg?L^?1 at 96?h of exposure. Bata larvae exposed to ammonia concentrations of 15.8–25?mg?L^?1 showed 10–74% mortalities. The 96?h LC₅₀ value for 200 (±5), 250 (±2) and 500 (±4) mg bata larvae were 11.5, 16.8 and 22.5?mg?L^?1 un-ionised ammonia concentrations, respectively. When fish were exposed to different doses of ammonia, behavioural changes immediately occurred even at the lowest dose. At first, the fish became hyperexcitable, the skin darkened and they showed an increased ventilation frequency, fish behaviour became normal, 24?h after exposure. A 96?h LC₅₀ value of un-ionised ammonia showed direct relationship with the increasing size of bata larvae.     

Bioaccumulation and toxic effects of copper on growth and oxygen consumption by the postlarvae of Penaeus indicus

The aim of this study was to assess the toxic impact of copper on postlarvae (PL) of the penaeid shrimp Penaeus indicus. Tolerance, growth, oxygen consumption and metal accumulation were investigated in these PL on exposure to copper. Tolerance studies were conducted for 96 h to assess the tolerance limits of P. indicus PL exposed to different concentrations of copper using static renewal bioassay tests. Using the Probit method, the regression equation was calculated as Y=0.4899+2.3562 X, with a correlation coefficient of 0.9707. The 96 h LC₅₀ was 0.8204 ppm. The effect of sublethal (one-fifth of 96 h LC₅₀) copper on PL for short- and long-term exposures revealed a significant (p<0.05) decrease in the rate of oxygen consumption, metabolic rate, mean length, wet and dry weight of the exposed PL over their respective controls which can be attributed to a gradual and time-dependent accumulation of the metal, as noticed in the exposed PL through accumulation studies. Overall, the data suggest that on chronic exposure even sublethal concentrations of copper can reduce the metabolic rate and growth in P. indicus PL. This is perhaps the first attempt to use the wild P. indicus PL as a bioindicator of copper toxicity.     

Survival and growth of bivalve larvae under heavy-metal stress

In a study of the toxicity of mercury, silver, copper, nickel, and zinc to larvae of the American oyster Crassostrea virginica and hard clam Mercenaria mercenaria, the concentrations at which 5% (LC₅), 50% (LC₅₀), and 95% (LC₉₅) of the larvae died were determined, as well as growth at the LC₅ and LC₅₀ values. The order of toxicity for oyster larvae was Hg>Ag>Cu>Ni, and for clam larvae Hg>Cu>Ag>Zn>Ni. Growth of larvae of both species, with the exception of clam larvae in nickel-treated water, was not reduced at the LC₅ values, but was markedly reduced at the LC₅₀ values.     

Influence of some abiotic environmental factors on acute toxicity of inorganic lead to Cyprinus carpio var communis (Linn.) and Catla catla (Ham.) in simulated toxic aquatic environment

With the increase of water hardness from 60 to 720?mg/L CaCO₃, total alkalinity from 32 to 376?mg/L CaCO_3, pH from 7.6 to 7.9 and chloride from 28 to 350?mg/L, 96?h LC₅₀ on the basis of total lead increased from 8.2 to 1291?mg/L for Cyprinus carpio and 5.3 to 865?mg/L for Catla catla, when soil sediments were included these values were further raised to 1356 and 874?mg/L, respectively. The dissolved lead LC₅₀ values in all the treatments of soil and water was consistent with fixed amount of dissolved lead (1.04–1.78?mg/L) being needed for median lethal toxicity. Total lead toxicity also decreased with increase in pH from 6.3 to 11.3. 96?h LC₅₀ values increased for common carp 15 to 631?mg/L and for catla, 8 to 355?mg/L. But dissolved lead toxicity was found to increase with the increase of pH from 6.3 to 11.3 for both common carp (LC₅₀, 3.53 to 0.24?mg/L) and catla (LC₅₀, 2.21 to 0.09?mg/L). Removal of dissolved Pb with increasing carbonate content, particulate matter and pH due to adsorption, precipitation or coprecipitation reaction, reduced the dissolved lead concentration and thus the total lead toxicity. Increase in toxicity of lead with increase of exposure time was the biological response of longer contact time and decrease in dissolved lead toxicity with decrease in pH was due to increase H⁺ ion competition.     

Acute toxicity of 30 pharmaceutically active compounds to freshwater planarians,Dugesia japonica

Pharmaceutically active compounds are produced worldwide and consumed in large quantities, so these chemicals are frequently detected in limnic environments posing potential ecological risks. Thirty pharmaceutically active compounds were selected for examination of their acute toxicity for freshwater planarians (Dugesia japonica). Among the 30 compounds tested, diclofenac, mefenamic acid, naproxen, propranolol HCl, and diphenhydramine HCl had a 48-h nominal LC₅₀ below10 mg L^?1, and for 18 chemicals, it exceeded 100 mg L^?1. The 96-h nominal LC₅₀ was below 10 mg L^?1 for diclofenac, mefenamic acid, naproxen, propranolol HCl, diltiazem HCl, diphenhydramine HCl, hydroxyzine HCl, and triprolidine HCl, and for 15 chemicals, it exceeded 100 mg L^?1. Among different therapeutic groups, analgesics were most toxic to planarians, and antibiotics were least toxic. Antihistamines and beta blockers varied in their acute toxicity to planarians. At the current environmental levels, none of the tested pharmaceutically active compounds may have acutely harmful impacts on aquatic invertebrates. To answer the question whether chronic, long-term exposure to pharmaceutically active compounds may entail ecological risks for aquatic ecosystems, further investigations with different end points in multiple species tests are needed.     

Acute toxicity of benzophenone-type UV filters and paraben preservatives to freshwater planarian,Dugesia japonica

Fourteen benzophenone-type UV filters and four paraben preservatives were selected to examine their acute toxicities on Dugesia japonica. The 48-h LC₅₀ values for planarians exposed to benzophenone-type UV filters can be ranked as oxybenzone?>?mexenone?>?5-chloro-2-hydroxybenzophenone?> 2,4-dihydroxybenzophenone?>?2-hydroxybenzophenone?>?dioxybenzone?>?benzophenone?>?2,2′,4,4′-tetrahydroxybenzophenone?>?4-hydroxybenzophenone?> 3-hydroxybenzophenone?>?4,4′-dihydroxybenzophenone?>?2,2′-dihydroxy-4,4′-dimethoxybenzophenone?>?2,3,4-trihydroxybenzophenone?>?sulisobenzone with a range from 0.9 to 145?mg?L^?1 with a similar sequence for the 96?h LC₅₀ values, ranging from 0.5 to 77?mg?L^?1. The 48 and 96?LC₅₀ values for planarians exposed to paraben preservatives can be ranked as butylparaben?>?propylparaben?>?ethylparaben?>?methylparaben. Among all the tested chemicals, oxybenzone was the most toxic and sulisobenzone the least toxic chemical to planarian at each exposure period. Most benzophenone-type UV filters are toxic to aquatic animals with 48?h LC₅₀ values less than 10 mg?L^?1, except for 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,3,4-trihydroxybenzophenone, and sulisobenzone. Because of their common occurrence in aquatic environment, more studies on aquatic toxicities of benzophenone-type UV filters and paraben preservativs are needed to provide important information to adequately assess their ecological risk.     

The toxicity of heavy metals to embryos of the American oyster Crassostrea virginica

The acute toxicity of 11 heavy metals to embryos of the American oyster Crassostrea virginica was studied and the concentrations at which 50% of the embryos did not develop were determined. The most toxic metals and their LC₅₀ values were mercury (0.0056 ppm), silver (0.0058 ppm), copper (0.103 ppm) and zinc (0.31 ppm). Those metals that were not as toxic and their LC₅₀ values were nickel (1.18 ppm), lead (2.45 ppm) and cadmium (3.80 ppm). Those metals that were relatively non-toxic and their LC₅₀ values were arsenic (7.5 ppm), chromium (10.3 ppm) and manganese (16.0 ppm). Aluminum was non-toxic at 7.5 ppm, the highest concentration tested.     

Experimental study on acute effects of the combined exposure to temperature increase and chlorination upon the marine copepod Acartia omorii

The acute effects of combined exposure to temperature increase and chlorination on a neritic marine copepod, Acartia omorii Bradford (collected offshore of Onjuku, Japan in 1982), were investigated in the laboratory. Continuous flow exposure and batch exposure modes were compared. Based on the results of continuous flow experiments, the 24-h median lethal concentration (24-h LC₅₀, in mg l^-1) of total residual chlorine was estimated using the multiple regression equation below, with a multiple correlation coefficient of 0.955: 24-h LC₅₀=2.988-0.034 dT-1.611 log₁₀ t where dT is temperature rise (°C) and t is exposure duration (min). In batch experiments, the predictive power of the multiple regression equation was reduced, probably due to variations in chlorine concentration during exposure duration.     

Effect of cadmium on survival and osmoregulation of various developmental stages of the shrimp Penaeus japonicus (Crustacea: Decapoda)

The object of this study was to evaluate the acute toxicity of cadmium in different post-embryonic stages of the penaeid shrimp Penaeus japonicus (Bate, 1888) and to determine the effect of sublethal cadmium on the osmoregulatory capacity used as an indicator of physiological condition. Tolerance to cadmium increases with the developmental stage. The least tolerant stages are the nauplii (48 h LC₅₀: 124 g Cd l^-1) and the zoeae (96 h LC₅₀: 10 to 30 g Cd l^-1). The most tolerant stages are the postlarvae (96 h LC₅₀: 200 to 3500 Cd l^-1) and juveniles (96 h LC₅₀: 5500 g Cd l^-1). In juvenile shrimp, 2000 g Cd l^-1 significantly reduce hypo- and hyper-OC. The effect of cadmium on hypo- and hyper-osmoregulatory capacity illustrates a dose- and time-dependent response. Surviving shrimp recover their hypo-osmoregulatory capacity after 6 d of readaptation in cadmium-free seawater.     

Comparative toxicities of 10 widely used biocides in three freshwater invertebrate species

Owing to their widespread use in wooden products, industrial products, cosmetics, and personal care products, biocides are frequently detected in wastewater and surface water. In this study, I examined the acute toxicities of 10 commonly used biocides, namely methylisothiazolinone, benzisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, iodopropynyl butylcarbamate, triclosan, azoxystrobin, pyraclostrobin, climbazole, and clotrimazole, in the water flea (Daphnia similis), freshwater planarians (Dugesia japonica) and green neon shrimp (Neocaridina denticulata). Among the 10 tested biocides, dichlorooctylisothiazolinone was the most toxic to both D. similis and N. denticulata, whereas pracolstrobin was the most toxic to Du. japonica. By contrast, the least toxic biocides for D. similis, Du. japonica, and N. denticulata were climbazole, iodopropynyl butylcarbamate, and methylisothiazolinone, respectively. The 48-h nominal LC₅₀ values of all the biocides, except for benzisothiazolinone and climbazole, in D. similis were mostly less than 1 mg/L. In addition, the 96-h nominal LC₅₀ values of all the biocides, except for methylisothiazolinone and iodopropynyl butylcarbamate, in Du. japonica was less than 1 mg/L. These results indicate the biocides with low LC₅₀ values are relatively toxic to freshwater organisms.     

丙硫菌唑对斑马鱼的安全性评价及其生物富集行为研究

丙硫菌唑是一种市场前景非常好的新型广谱杀菌剂。本文研究了丙硫菌唑对水生生物斑马鱼的急性毒性和生物累积风险。通过斑马鱼的急性毒性试验获得丙硫菌唑对斑马鱼的96 h-LC₅₀为2.06 mg a.i. L^-1。随后,采用0.02 mg L^-1 (1/100LC₅₀)和0.2 mg L^-1 (1/10LC₅₀)2个浓度的丙硫菌唑,通过8 d实验,获得其在斑马鱼体内的生物累积效应。在0.02 mg L^-1组中,第8天时,斑马鱼体内的浓度达到0.733 mg kg^-1,生物富集系数(BCF_{8 d})缓慢增长到34.36。而在0.2 mg L^-1组,第8天时,斑马鱼组织内丙硫菌唑浓度为4.198 mg kg^-1, BCF_{8 d}值为19.72。结果表明,丙硫菌唑对斑马鱼的毒性等级为中毒,同时其在斑马鱼体内具有中等生物累积效应。因此,在使用过程中,需要考虑其对水生生物的毒性和水生食物链的放大效应。     

Determination of types of interactions exhibited by binary mixtures of heavy metals tested against the hermit crab,Clibanarius africanus

Single and joint action toxicity of heavy metal compounds (ZnCO₃, CuSO₄ and CdSO₄) were carried out against the hermit crab, Clibanarius africanus in laboratory bioassays. On the basis of 96?h LC₅₀ values, CuSO₄ (96?h LC₅₀?=?0.03?mM) was found to be the most toxic followed by CdSO₄ and ZnCO₃ (96?h LC₅₀?=?0.24?mM) in decreasing order of toxicity. The evaluation of the metal compounds in mixtures of ZnCO₃–CuSO₄, ZnCO₃–CdSO₄ and CdSO₄–CuSO₄ in pre-defined molar ratios revealed that interactions between Zn–Cu and Zn–Cd test mixtures were in conformity with the models of antagonism (reduction in toxicity of constituent metals). The synergistic ratios (S.R.s) and relationship between observed/predicted 96?h LC₅₀ values (relative toxic unit, RTU) were consistently below 1, indicating antagonistic interactions. Analysis using isobolograms also indicated the interactions between the mixture components to be antagonistic. However, with regards to CdSO₄–CuSO₄ test mixtures, the interactions between these metals were mainly in conformity with the model of synergism. The S.R. and RTU values were largely above 1, indicating synergistic interactions. The importance of the joint action evaluations for the management and protection of aquatic ecosystems, particularly in the setting up of water quality criteria was discussed.     

The influence of solid matrices on arsenic toxicity to Corophium orientale

In marine ecosystems, benthic organisms are really important because they are the first step in the transfer of contaminants from environment to biota. To this end, this study focused on biological assays with the amphipod Corophium orientale exposed to two different molecules of arsenic: arsenate (As^V), the most abundant form in sediments, and dimethyl-arsinate (DMA), expected to be moderately toxic as an intermediate in the process of detoxification. The toxicity of arsenic compounds was measured after exposure to three different matrices: water, spiked natural sediment and inert spiked quartz sand. LC₅₀ values were calculated for each exposure, and the results confirmed the highest toxicity of As^V, in addition to underlining the importance of matrix of exposure. Water exposure was the matrix which presented the highest toxicity for inorganic arsenic (As^V LC₅₀=3.51 mg L^?1 vs DMA LC₅₀=54.65 mg L^?1), spiked natural sediment demonstrated its capability to chelate arsenate toxicity (As^V LC₅₀=34.27 mg kg^?1 vs. DMA LC₅₀=52.19 mg kg^?1) and spiked quartz sand presented intermediate values for As^V (LC₅₀=25.26 mg kg^?1), whereas for DMA a lower toxicity was registered (LC₅₀=872.35 mg kg^?1). This study can provide some useful data linked with chemical speciation of arsenic and exposure matrix, for improving the correct management of contaminated sediment.     

The effect of low concentrations of phenol and ammonia on egg production rates,fecal pellet production and egg viability of the calanoid copepod Acartia clausi

Estimates of daily fecundity, hatching success and fecal pellet production are reported for Acartia clausi females exposed for 10 d to low levels of phenol and ammonia. Copepods were collected in 1991 and 1992 from a southern coastal area of the Mar Grande of Taranto (southern Italy). A reduction in egg numbers and fecal pellet production was observed for females after 8 d of exposure to 500 g l^-1 phenol concentration. Ammonia (120 g l^-1) produced a significant increment in egg production, but hatching success was reduced by about 50% after nine exposure days. A. clausi was more sensitive to ammonia than phenol at high concentrations (24-h LC₅₀ phenol-32.26 mg l^-1; 24-h LC₅₀ ammonia=0.91 mg l^-1). At low concentrations, only long-term exposure to phenol determined a reduction in fecundity.