Series Of Acute Toxicity Tests Research Articles

Toxicity assessment of TiO2-conjugated Carbon-based nanohybrid material on a freshwater bioindicator cladoceran, Daphnia magna.

The application of nanocomposite materials fabricated from titanium dioxide nanoparticles (TiO2 NPs) and different carbon (C) allotropes have gained popularity in water treatment applications due to their synergistic properties. Studies to date have focused on simple forms of nanomaterials (NMs), however, with the technology development, there is a dramatic increase in production and application of these complex NMs which could result in toxicological impacts on organisms when released into aquatic environments. This raises serious concerns about their safety and the need to ascertain their potential adverse effects on aquatic organisms. While conjugated TiO2 NPs/carbon-based nanohybrids (TiO2/C-NHs) may exhibit enhanced photocatalytic activity, there is no research in the scientific community regarding their toxicological effects on D. magna, which are indicators of freshwater pollution. In this study, two under-represented TiO2/C-NHs (i.e., TiO2- conjugated carbon nanofiber (CNF), and TiO2-conjugated multi-walled carbon nanotube (CNT)) were investigated for their toxic effects on D. magna, through a series of acute toxicity tests with a set of sublethal biochemical biomarkers of oxidative stress. The lethal toxicity and oxidative stress formation of TiO2/C-NHs over 48h revealed a concentration-dependant increase in D. magna mortality. The primary mechanism identified was the generation of ROS, which was in line with toxicity results. Light microscopy and CytoViva® images visualized D. magna interaction with the NPs, which accumulated and appeared as dark materials in the lines of the gut tract. The collective results indicate that TiO2/C-NHs have the potential to cause an effect on freshwater organisms when released into the environment. However, the relevance of TiO2/C-NHs effects needs further chronic toxicity studies since they show promise to be used in nano-bioremediation materials to treat wastewaters.

Synergistic effect of piperonyl butoxide on acute toxicity of pyrethrins to Hyalella azteca.

A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrin toxicity. Concentrations of PBO <4 µg/L caused no toxicity enhancement, whereas toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrin toxicity (decrease in median lethal concentration) of 1.4-fold to 1.6-fold and varied only slightly between 4 µg/L and 15 µg/L PBO, whereas direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. The results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. Environ Toxicol Chem 2016;35:2111-2116. © 2016 SETAC.

Effect of Temperature on Acute Toxicity of Nitrite to Meagre, Argyrosomus regius (Asso, 1801)

AbstractMeagre, Argyrosomus regius, is a candidate marine fish species for aquaculture diversification, presenting a high economic value in the Mediterranean. Tolerance of juvenile meagre to nitrite (NO2‐N) was determined relating to temperature. Fish (3.2 ± 0.6 g and 5.4 ± 0.9 cm) were exposed to different NO2‐N concentrations in a series of acute toxicity tests by the static renewal method at three temperatures (18, 22, and 26 C) at a pH of 8.0. Low temperature clearly increased tolerance to NO2‐N (P &lt; 0.05). The 96‐h median lethal concentration (LC50) values of NO2‐N were 177.63, 139.55, and 49.61 mg/L, at 18, 22, and 26 C, respectively. The safe levels of NO2‐N for juvenile meagre were estimated to be 17.7, 13.9, and 4.9 mg/L at 18, 22, and 26 C, respectively (P &lt; 0.05). This study indicates A. regius is more sensitive to nitrite than other marine fish species cultured in the Mediterranean.

Acute toxicity of ammonia in Meagre (Argyrosomus regiusAsso, 1801) at different temperatures

Argyrosomus regius (3.0 ± 0.9 g) were exposed to different concentrations of ammonia in a series of acute toxicity tests by the static renewal method at three temperature levels (18, 22 and 26°C) at a pH of 8.2. Low temperature clearly increased the tolerance of the fish to total ammonia nitrogen (TAN) and unionized ammonia (NH3) (P < 0.05). While the 96-h LC50 values of TAN were 19.79, 10.39 and 5.06 mg L−1, the 96-h LC50 of NH3 were 1.00, 0.70 and 0.44 mg L−1 at 18, 22 and 26°C respectively. The safe levels of NH3 for A. regius was estimated to be 0.10, 0.07 and 0.04 mg L−1 at 18, 22 and 26°C respectively (P < 0.05). This study clearly indicates that A. regius is more sensitive to ammonia than other marine fish species cultured on the Mediterranean and Eastern Atlantic coasts.

Effects of Salinity on Acute Toxicity of Ammonia and Oxygen Consumption Rates in Common Prawn, Palaemon serratus (Pennat, 1777)

AbstractPalaemon serratus juveniles (0.18 ± 0.06 g) were exposed to different concentrations of ammonia in a series of acute toxicity tests by the static renewal method at four salinity levels (10, 20, 30, and 40 ppt) at 29 C and at a pH of 8.0. Oxygen consumption rate (OCR) was also measured. The mortality rate increased with increasing concentrations of ammonia and longer exposure times. High salinity levels clearly increased the tolerance of shrimp to total ammonia nitrogen (TAN) and unionized ammonia (NH3) (P &lt; 0.05). The safe level for P. serratus was estimated to be 2.1, 3.5, 3.8, and 8.5 mg/L for TAN and 0.13, 0.21, 0.24, and 0.53 mg/L for NH3 at 10, 20, 30, and 40 ppt salinity levels, respectively. OCR of P. serratus increased with increasing salinity and TAN concentrations. This study clearly indicated that there is a relationship between an increment in salinity or TAN and the OCR of P. serratus juveniles (P &lt; 0.05).

Variation in toxicity of a current-use insecticide among resurrected Daphnia pulicaria genotypes.

This study examined how genotypes of Daphnia pulicaria from a single population, separated by thousands of generations of evolution in the wild, differ in their sensitivity to a novel anthropogenic stressor. These genotypes were resurrected from preserved resting eggs isolated from sediments belonging to three time periods: 2002-2008, 1967-1977, and 1301-1646 A.D. Toxicity of the organophosphate insecticide chlorpyrifos was determined through a series of acute toxicity tests. There was a significant dose-response effect in all genotypes studied. Moreover, significant variation in toxicity among genotypes within each time period was detected. Importantly, a significant effect of time period on sensitivity to chlorpyrifos was found. Analysis of the median effect concentrations (EC50s) for genotypes within each time period indicated that the 1301-1646 genotypes were 2.7 times more sensitive than the 1967-1977 genotypes. This trend may be partially explained by microevolutionary shifts in response to cultural eutrophication.

Comparison of TiO2 nanoparticle and graphene–TiO2 nanoparticle composite phototoxicity to Daphnia magna and Oryzias latipes

With a dramatic rise in complexity, needs of nanotoxicology research go beyond simple forms of nanomaterials. This study compared the phototoxicity of nano-TiO2 and graphene–TiO2 nanocomposite (GNP). GNP was synthesized based on a hydrothermal method, which simultaneously performed the reduction of graphene oxide and nano-TiO2 loading. A series of acute toxicity tests of nano-TiO2, graphene and GNP was performed on two aquatic organisms, Daphnia magna and Oryzias latipes. Fast and substantial agglomeration and sedimentation of nanoparticles in test media and surface attachment of nano-TiO2 and GNP on D. magna surface was observed. Similar phototoxicity of nano-TiO2 and GNP for both species existed, though compared with nano-TiO2, GNP had a 2.3-fold increase in visible light photocatalytic ROS generation. In summary, this study demonstrated the significance of illumination spectrum, particle behavior, and species sensitivity on nanophototoxicity, and the needs for research on increasingly sophisticated functional materials.

Toxic effects, bioconcentration and depuration of verapamil in the early life stages of common carp (Cyprinus carpio L.)

Verapamil is a pharmaceutical that belongs to a group of calcium channel blockers and is mainly used as a treatment of angina pectoris and arterial hypertension. Verapamil has been detected in aquatic environments in concentrations ranging from ng L−1 to μg L−1. In the present study, a series of acute toxicity tests of verapamil on various developmental stages of common carp (Cyprinus carpio) were conducted. As a result, 96hLC50 values of verapamil were estimated at 16.4±9.2, 7.3±1.5 and 4.8±0.2mgL−1 for embryos (E5–E9) and common carp larvae L2 and L5, respectively. Lethal concentrations of verapamil decreased with an increase in the age of the fish. Acute exposure to verapamil significantly reduced the heart rate in the embryos and larvae. In an embryo-larval toxicity test (sub-chronic exposure), the bioconcentration, depuration, and toxic effects of verapamil were assessed in common carp. The fish were exposed to verapamil in a concentration of 0.463 (environmentally relevant), 4.63, 46.3 and 463μgL−1. Verapamil had no effect on the accumulated mortality, hatching, condition factor, growth or ontogeny of the fish in any of the tested concentrations. In carp exposed to 463 and 46.3μgL−1 of verapamil, significantly higher occurrences of malformations and edemas were observed compared to the control. The bioconcentration factor of verapamil in whole fish homogenates ranged between 6.6 and 16.6 and was therefore below the critical value for hazard substances (BCF>500). The half-life and the 95% depuration time for the tested compound were estimated to be 10.2±1.6days and 44.2±8.6days, respectively. No effects of verapamil on the studied endpoints were observed at environmentally relevant concentrations.

The environmental toxicity of Dicerothamnus rhinocerotis and Galenia africana

Over the years the use of pesticides has greatly increased. This in turn has lead to concern about the adverse effects that the pesticides may have on non-target organisms in the environment. Due to increasing awareness there is great pressure to reduce the use of synthetic pesticides. An alternative to the use of synthetic pesticides is the exploitation of natural botanical products with pesticidal potential.Dicerothamnus rhinocerotis and Galenia africana are plants, indigenous to South Africa, with fungicidal properties against a fungal pathogen that causes grey-mould rot on a wide range of agricultural produce. In this study a series of acute toxicity tests were conducted to estimate the potential environmental effect of D. rhinocerotis and G. africana. The acute toxicities of the plants were determined using the species Daphnia pulex, Selenastrum capricornutum, Vibrio fischeri andPoecilia reticulata as bio-indicators. Results obtained showed that G. africana had higher toxicity units than D. rhinocerotis, thus showing that G. africana is more toxic to the aquatic environment compared to D. rhinocerotis. Key words: Pesticides, Galenia africana, Dicerothamnus rhinocerotis, acute toxicity.

Acute toxicity of copper and silver to Ceriodaphnia dubia in the presence of food

Food is added to exposure solutions in cladoceran chronic toxicity tests and sometimes in acute toxicity tests, but its effects on the bioavailability of toxicants have not been studied extensively. We compared the toxicity of waterborne Ag and Cu to Ceriodaphnia dubia in the presence or absence of food (a mixture of a yeast--Cerophyll--trout chow slurry and a green alga) in two series of acute toxicity tests. In the first series, we added food to Ag or Cu exposure solutions 0, 30, 60, or 120 min before transferring C. dubia into the solutions. In the second series, we exposed C. dubia to waterborne Ag or Cu for 30, 60, and 120 min in the absence of food. Adding food before transferring C. dubia into the exposure solutions greatly decreased the toxicity of Ag, but had less effect on the toxicity of Cu. In contrast, adding food after transferring C. dubia into the exposure solutions did not alter the toxicity of Ag considerably and did not alter the toxicity of Cu as much as the reverse sequence. Median effects concentrations (EC50s) for 30-, 60-, and 120-min unfed Ag tests were within the range of EC50s for 48-h unfed Ag tests, suggesting most uptake that contributes to acute Ag toxicity to C. dubia occurs within the first 30 to 60 min. However, uptake that contributes to acute Cu toxicity to C. dubia appears to occur over more than 2 h. Therefore, standard food decreases the toxicity of waterborne Ag and Cu to C. dubia, and the timing of adding food to exposure solutions is especially important in Ag tests.

Effects of temperature on acute toxicity of ammonia to Penaeus semisulcatus juveniles

Penaeus semisulcatus juveniles (1.6±0.2 g) were exposed to different concentrations of ammonia-N in a series of acute toxicity tests by the semi-static method at four different water temperatures (14, 18, 22 and 26 °C) at pH of 8.2 and 39 ppt salinity. The mortality rate increased with increasing concentrations of ammonia and exposure time. Low temperatures clearly increased tolerance of the shrimps to total ammonia-nitrogen (TAN) and un-ionised ammonia (NH 3-N). The 24-, 48-, 72- and 96-h LC 50 values of TAN were 92.22, 76.56, 64.07 and 55.84 mg l −1 at 14 °C; 57.00, 46.07, 41.85 and 36.01 mg l −1 at 18 °C; 41.10, 33.42, 30.61 and 26.72 mg l −1 at 22 °C; and 25.89, 15.44, 13.44 and 11.44 mg l −1 at 26 °C, respectively. The 24-, 48-, 72- and 96-h LC 50 values of NH 3-N were 3.18, 2.64, 2.22 and 1.92 mg l −1 at 14 °C; 2.94, 2.37, 2.15 and 1.85 mg l −1 at 18 °C; 2.77, 2.25, 2.06 and 1.80 mg l −1 at 22 °C; and 2.26, 1.35, 1.17 and 1.00 mg l −1 at 26 °C, respectively. The safe level for rearing P. semisulcatus was estimated to be 5.6, 3.6, 2.7 and 1.1 mg l −1 for TAN and 0.19, 0.19, 0.18 and 0.10 mg l −1 for NH 3-N at 14, 18, 22 and 26 °C water temperatures, respectively. The safe level was fivefold higher for TAN and twofold higher for NH 3-N at 14 °C in comparison to 26 °C.

Histopathological, serum enzyme, cholesterol and urea changes in experimental acute toxicity of ammonia in common carp Cyprinus carpio and use of natural zeolite for prevention

Commoncarp, Cyprinus carpio, was exposed to ammonia in a seriesof acute toxicity tests at 20–22 °C. 24 -hLC50 values were estimated 123 mg/l total ammonia-N (45.5mg/l molecular ammonia-N). In the lethal concentration of ammoniafor common carp (150 mg/l total ammonia), the application of 10g/l natural zeolite prevented the fish mortalities. Inhistopathologic study, the most important lesions that encountered in the gillwere hyperemia, edema and aneurysm. In the kidney, degenerative changes oftubules and glumeruli, expansion of Bowman's capsules, hyperemia, congestionandhemorrhage were the most prominent lesions. There were hyperemia, degenerationand the presence of some necrotic aria as the only lesions observed in theliver. In the serum the level of alkaline phosphatase (ALP) and urea ofexperimental groups were significantly higher than the control. There was nosignificant difference in other enzymes and cholesterol level betweenexperimental groups and control fishes.

The Acute Toxicity of Selected Alkylphenols to Young and AdultDaphnia magna

Differences in sensitivity toward toxicants between young and adult individuals in a population are assumed to be primarily associated with their difference in body size. This assumption plays a key role in the modeling of effects of variable concentrations of toxicants on nonhomogeneous populations. The hazard-based no-effect-concentrations (NECs), killing rates, and elimination rates, estimated from the survival data of a series of acute toxicity tests with young and adults ofDaphnia magnaand six alkylphenols, were used to evaluate this assumption. The results lead to the conclusion that young and adultD. magnawere equally sensitive in terms of NEC and killing rate and that the observed differences in elimination rates could be explained on the basis of a difference in body size. Furthermore, it was found that elimination rates estimated on the basis of the survival data were consistently smaller than those expected on the basis of a QSAR forDaphnia pulex, a comparable species. This discrepancy was likely due to a decreased uptake and elimination during a period of immobilization prior to death. Since it is unknown to what extent immobilized individuals are able to recover from short-term exposures, the observed deviation clearly identifies a complicating factor in the modeling of effects of variable concentrations of toxicants.

Acute toxicity of ammonia to various life stages of the São Paulo shrimp, Penaeus paulensis Pérez-Farfante, 1967

Each life stage of the São Paulo shrimp, Penaeus paulensis, was exposed to ammonia in a series of acute toxicity tests, by the semistatic method, at 25 °C and salinity at 28 ppt. A pronounced sensitivity was observed in the egg stage. In this phase, 0.30 mg/l NH 3-N caused death of 50% of the embryos. The 24-h LC 50 values for nauplii, zoeae, myses and postlarvae were, respectively, 102.30, 22.93, 74.87 and 24. 19 mg/l total ammonia-N (4.25, 1.79, 2.91 and 1.40 mg/l NH 3-N). The 96-h LC 50 values for zoeae, myses and postlarvae were 9.39, 21.98, 5.49 mg/l total ammonia-N (0.73, 0.85 and 0.32 mg/l NH 3-N). The LC 50 of ammonia for juveniles (5.45 ± 0.4 g mean live-weight) and for adults (31.43 ± 1.3 g mean live-weight) were also measured. The 24-h LC 50 values for juveniles and adults were, respectively, 51.87 and 61.63 mg/l total ammonia-N (1.47 and 1.59 mg/l NH 3-N) and the 96-h LC 50 values were 38.72 and 42.49 mg/l total ammonia-N (1.10 and 1.06 mg/l NH 3-N). An analysis of variance showed that there was no direct relationship between shrimp development and its tolerance to ammonia ( P > 0.05) and that eggs, zoeae and postlarvae are very sensitive to ammonia:. The “safe level” for rearing P. paulensis was estimated to be 0.03 mg/l NH 3-N. In general, P. paulensis is less resistant to ammonia than other species of shrimp.

A proposal for the reduction of animal numbers required for the acute toxicity to fish test (LC 50 determination)

Juvenile rainbow trout ( Salmo gairdneri) were exposed to 10 common industrial and agricultural chemicals in a series of acute toxicity tests to provide data for the evaluation of the test design currently employed in hazard assessment for novel chemicals in the aquatic environment. Analysis of these data revealed that the widely employed design of 10 fish at each of 5 concentrations covering one order of magnitude could be modified to one of 7 fish at each of 4 concentrations with minimal reduction in the precision of the result (i.e., the LC 50 value). The adoption of this modification to test design, however, would result in a reduction of approximately 40% of the number of experimental animals used in bioassay programmes.